09:00 - 10:35
Geist, Thomas - FFG, Austria
Welcome address - opening
ESA Earth Observation Satellites for Atmospheric Chemistry and Dynamics
Borgeaud, Maurice - ESA/ESRIN, Italy
ATMOS-2018 Introduction and Objectives
Retscher, Christian - ESA/ESRIN, Italy
Observing the Changing Anthropocene: the Needs, the Evolving Observing System and Opportunities for New Space
Burrows FRS, John P. - University of Bremen, Germany
Pollution in the atmosphere now spans all scales from the local to the global. Air quality, stratospheric ozone and climate change are all being influenced by anthropogenic activity. This is a result of the increasing population, which has risen from 1 Billion at the industrial revolution to 7.6 Billion presently The earth system has entered a new geological epoch, the Anthropocene. To understand the impact of anthropogenic activity and natural phenomena, global measurements of atmospheric trace constituents are required at adequate spectral resolution and temporal sampling.
The SCIAMACHY (Scanning Imaging Absorption spectrometer for Atmospheric CHartographY) project, which began in 1984, addressed the objective of measuring trace gases, aerosols and clouds from space based passive remote sensing in the solar spectral range. This initiative led to the following instruments being developed and launched on satellite platforms into sun synchronous low earth orbit: GOME (Global Ozone Monitoring Experiment - ESA ERS-2 1995-2011), SCIAMACHY (ESA Envisat 2002 to 2012) GOME_2 (EUMTSAT Metop A 2006 to present, Metop B 2012 to present, Metop C to be launched in late 2018). In addition, the spin off OMI (Ozone Monitoring Instrument - NASA AURA 2004 to present) was developed by NSO/NASA and ESA/NSO recently developed Sentinel 5 Precursor (2017 –present). Sentinel 4, which builds on the heritage of SCIAMACHY and the GeoSCIA proposals will be launched as part of MTG-2(2021-2037) and Sentinel 5 as part of the Metop Second Generation (2021- 2036). SCIAMACHY had the widest spectral range 210 to 2038 nm. GOME, GOME-2 and Sentinel 4 observe in the UV, Visible NIR and OMI in the UV and Visible. Appropriate mathematical inversion of the measurements of these instruments yields information about the total stratospheric and tropospheric column amounts and distributions of the following gases, which are either short lived climate pollutants or greenhouse gases: O3, NO2, H2O, HCHO, CHO.CHO, BrO, IO, CO, CH4 and CO2.
The status of the evolving observing system is that the spectral resolution has now reached at best approximately 25 km2 once a day. This presentation will provide an analysis of needs for the evolving earth observing system, and update on the analysis at the University of Bremen of the time series provided by the above instruments. Finally, it will address opportunities for New Space developments of small satellites.
Sentinel-5 Precursor Mission Status and First Results
Zehner, Claus (1); Veefkind, Pepijn (2); Loyola, Diego (3); Aben, Ilse (4); Van Roozendael, Michel (5); Dehn, Angelika (1); Martin, Jolyon (1); Houghton, Nigel (1) - 1: ESA/ESRIN, Italy; 2: KNMI, The Netherlands; 3: DLR, Germany; 4: SRON, The Netherlands; 5: BIRA/IASB, Belgium
The Sentinel-5 Precursor mission, launched on Oct. 13 2017, is the first atmospheric Sentinel and supports Copernicus services in particular for atmospheric applications, including activities such as air quality, ozone and climate monitoring. The instrument TROPOMI (Tropospheric Monitoring Instrument) is the single payload of the Sentinel-5 Precursor satellite and was co-funded by The Netherlands. Sentinel-5 Precursor ensures on the one hand continuity of atmospheric satellite data provision from the ESA ERS (GOME), ENVISAT (SCIAMACHY), and the USA EOS-AURA (OMI) missions in the various application and scientific domains and prepares on the other hand for the future atmospheric Sentinel-4 and Sentinel-5 instruments hosted on EUMETSAT platforms. The Sentinel-5 Precursor Commissioning Phase was successfully finalised on April 24 2018. Since then the mission is in the so-called ramp-up phase with a planned duration of 8 months. During this phase the Sentinel-5 Precursor products are being released to the public in a staggered approach and the Payload Data Ground Segment (PDGS) services are gradually upgraded to reach full operations capacity. This presentation provides on overview about the Sentinel-5 Precursor mission status and its products.
Status of ESA's Doppler Wind Lidar mission Aeolus
Fehr, Thorsten - ESA/ESTEC, The Netherlands
11:05 - 12:20
The Copernicus atmospheric composition missions Sentinel-4 and -5
Veihelmann, Ben; Wright, Norrie; Bazalgette Courrèges-Lacoste, Grégory; Erdmann, Matthias; Bagnasco, Giorgio; Martin, Didier - ESA/ESTEC, The Netherlands
The Copernicus missions Sentinel-4 and Sentinel-5 are designed to provide the atmospheric composition observations needed by the Copernicus Atmosphere Monitoring Service. This presentation covers an overview of the two missions, their atmospheric composition products, and their mission implementation status.
The EUMETSAT Contribution to the Sentinel Missions for Atmospheric Composition
Munro, Rosemary; Bojkov, Bojan; Provost, Dany; Wilson, Hilary; Schluessel, Peter; Grandell, Jochen; Fougnie, Bertrand - EUMETSAT, Eumetsat-Allee 1, 64295, Germany
As part of the Copernicus tasks entrusted to EUMETSAT by the European Commission under the Delegation Agreement, Building Block 2, ATSE Atmospheric Services, EUMETSAT will deliver operational Near Real Time (NRT) data and support services for the Copernicus Sentinel-4 mission to be hosted on the MTG-S platform, the Copernicus Sentinel-5 mission to be hosted on the EPS-SG A platform, and NRT atmosphere products and services from Sentinel-3. In addition to the benefits that arise from EUMETSAT’s demonstrated expertise in the provision of operational data products and services, the availability of data and products from EUMETSAT’s own missions brings a wealth of opportunities, in particular related to the potential for the development of synergistic products.
In this presentation we provide an overview of the full suite of instruments relevant to atmospheric composition on the EPS-SG and MTG platforms and highlight the additional value that EUMETSAT brings through this extensive suite of data and products. Particular attention will be paid to the possibility for development of novel synergistic products.
The FORUM EE9 Proposed Mission: Potentiality of Measurements and Synergies with IASI-NG
Ridolfi, Marco (1,2); Palchetti, Luca (2); Brindley, Helen (3); Del Bianco, Samuele (4); Dinelli, Bianca Maria (5); Labonnote, Laurent (6); Maestri, Tiziano (1); Sounders, Roger (7) - 1: University of Bologna, Italy; 2: Istituto Nazionele di Ottica - CNR, Firenze - Italy; 3: Imperial College, London, United Kingdom; 4: Istituto di Fisica Applicata "Carrara" - CNR, Firenze, Italy; 5: Istituto di Scienze dell'Atmosfera e del Clima - CNR, Bologna, Italy; 6: University of Lille 1, Lille, France; 7: Met Office, Exeter, United Kingdom
In November 2017 the European Space Agency selected FORUM (Far-infrared Outgoing Radiation Understanding and Monitoring) as one of the two instrument concepts to be developed further and to compete to be the ninth Earth Explorer mission. FORUM will be a Far-Infrared Spectrometer measuring the upwelling spectral radiance emitted by the Earth across the most relevant infrared part of the electromagnetic spectrum from satellite. In particular, the instrument will cover the spectral range from 100 to 1600 cm −1 (from 100 to 6.25 microns in wavelength), covering the Far InfraRed (FIR), including the 100 and 667 cm −1 band, which has never been spectrally resolved from space before.
Idealized model simulations suggest that between one quarter and one third of the total clear-sky long-wave cooling of the Earth to space occurs within the FIR spectral region. An even larger fraction of this cooling is predicted to occur in the FIR under all-sky conditions, because the presence of clouds causes lower emitting temperatures, and hence a shift to longer wavelengths of the peak of the black-body curve. For this reason, a detailed study of the Earth’s radiation budget requires accurate, frequent, and global-coverage measurements of the total upwelling irradiance. In this work we will show how FORUM measurements will permit to obtain a very accurate estimate of the upwelling FIR irradiance. Furthermore, the spectral resolution of the measurements will enable to disentangle the contributions of the various contributions (due to gases, surface, clouds) to the outgoing long-wave flux.
Since the FIR part of the upwelling spectral radiance is particularly sensitive to the water vapor content in the Upper Troposphere, FORUM measurements will effectively complement, by flying in tandem with MetOp, the Middle-InfraRed spectrum that will be measured by IASI-NG. In this paper we will show how FORUM and IASI-NG measurements could be synergistically exploited to improve the present knowledge of the water vapor amount in the Upper Troposphere.
The ALTIUS Mission : Combining Operational Needs and Atmospheric Research
Fussen, Didier (1); Baker, Noel (1); Demoulin, Philippe (1); Debosscher, Jonas (1); Dekemper, Emmanuel (1); Errera, Quentin (1); Franssens, Ghislain (1); Mateshvili, Nina (1); Pereira, Nuno (1); Pieroux, Didier (1); Vanhellemont, Filip (1); Navarro-Reyes., Daniel (2); Bernaerts, Dirk (2); Montrone, Luciana (2); Santandrea, Stefano (2); Sarna, Karolina (2); Frommknecht, Bjoern (2); Wehr, Tobias (2) - 1: Belgian Institute for Space Aeronomy (BISA), Belgium; 2: ESA/ESTEC, Earth Observation, Netherlands
The ALTIUS project was initiated in 2005 by the Royal Belgian Institute for Space Aeronomy (BISA) and proposed as an EarthWatch element for subscription by interested countries at the last ESA ministerial council in Dec 2016. Operating onboard an agile PROBA platform, ALTIUS is aimed at atmospheric limb sounding with high vertical resolution.
The mission design will combine bright limb observations, providing a high spatial and temporal coverage, and solar-stellar-planet-lunar occultations in inertial pointing, allowing for high accuracy measurements. The innovative principle of ALTIUS is to take pictures of the earth’s limb with a 2D spectral camera equipped with acousto-optic or Fabry-Perot tunable filters .
ALTIUS is designed to measure limb radiances between 10 and 100 km, in the 250 to 1800 nm wavelength range, with 3 independent spectral cameras capable of detecting vertical extinction profiles of several absorbers. The mission objective is twofold:
The autonomy of the ALTIUS space segment allows for a quite elaborated mission scenario to combine several observation geometries and/or calibration campaigns. The baseline mission scenario will be presented as well as various specific observations with dedicated scientific objectives.
The ALTIUS space segment is currently in a design consolidation phase. In parallel, the Payload Data Ground Segment is now under study and the general structure of the Data Processing Model has been developed by BISA while the necessary processing algorithms are identified and/or optimized. Preliminary results of the expected performances will be compared with respect to mission objectives. Open questions and suggestions for operational needs and atmospheric research will be discussed with the atmospheric science community.
The EarthCARE mission
Eisinger, Michael - ESA/ECSAT, UK
13:50 - 15:40
Measuring Carbon Dioxide and Methane from Space: Progress and Plans
Crisp, David - Jet Propulsion Laboratory, California Institute of Technology, United States of America
Spatially- and temporally-resolved measurements of atmospheric CO2, CH4, and other GHGs can provide an integrated constraint on the net exchange of these gases between the surface and the atmosphere. If these atmospheric measurements are integrated into a comprehensive atmospheric GHG monitoring system, they could form the basis of a Measurement, Reporting and Verification (MRV) approach that complements the bottom-up inventories used to track anthropogenic emissions. They could also provide timely insight into changes in the natural carbon cycle as it evolves in response to climate change. Estimates of XCO2 and XCH4 from space-based observatories could play a crucial role in this atmospheric carbon monitoring system by detecting emission hot spots and providing improved estimates both natural and anthropogenic fluxes on urban to regional scales. The principal advantage of this approach is that it can yield frequent measurements at high spatial resolution over most of the globe, including areas that are too geographically or politically inaccessible to support ground-based stations. The principal challenge has been the need for unprecedented precision and accuracy in the XCO2 and XCH4 estimates used to quantify surface sources and sinks. Great progress has been made in these areas by the EVISAT/SCIAMACHY, GOSAT/TANSO-FTS and OCO-2 missions. These sensors are now yielding estimates of XCO2 with single sounding random errors between 0.1 and 0.3% (0.4 to 1.2 ppm) and systematic biases between 0.25 and 0.5% (1 to 2 ppm) over most of the globe. These results are being used to quantify natural CO2 sources and sinks on regional scales, to detect CO2 gradients across large urban areas and in selected cases, to quantify emissions from large, coal-fired power plants. For XCH4, these systems have demonstrated single sounding random errors are near 13 ppb and systematic biases are between 0.2 and 0.4% (4 and 7 ppb). While these experiments clearly demonstrate the potential value of space-based CO2 and CH4 measurements, additional advances are needed to meet the increasingly demanding requirements for precision, accuracy, resolution, and coverage. This presentation summarizes the current state of the art, near-term plans and the prospects for an operational, space-based constellation designed to quantify CO2 and CH4 fluxes on urban to national scales.
Anthropogenic CO2 Monitoring as Candidate Copernicus Expansion Mission
Meijer, Yasjka (1); Pinty, Bernard (2) - 1: ESA/ESTEC, Noordwijk, The Netherlands; 2: EC, DG-GROW, Brussels, Belgium
Contributions from ESA and MAG experts
Major international institutions
As part of the European Copernicus Programme, the European Commission (EC) and the European Space Agency (ESA) together with the support of Eumetsat and the European Centre for Medium-range Weather Forecasts (ECMWF) are considering to further develop the first generation Copernicus Space Component to include measurements for fossil CO2 emission monitoring. The greatest contribution to the increase in atmospheric CO2 comes from emissions from the combustion of fossil fuels and cement production. Current uncertainties associated with their emission estimates at national and regional scales may translate into ill-informed policy decisions and limitations in assessing the effectiveness of CO2 emission strategies.
Satellite and in-situ atmospheric measurements, in addition to bottom-up inventories, would enable the transparent and consistent quantitative assessment of CO2 emissions and their trends at the scale of megacities, regions, countries, and the globe as well. Such a capacity would provide the European Union with a unique and independent source of information, which can be used to inform on the effect of policy measures, and to track their impact en-route towards decarbonizing Europe and meeting national emission reduction targets. Further, there would be potential synergies at international level with observation systems under discussion with other third parties.
This presentation will provide an overview of the CO2 monitoring mission objectives, the observational requirements on CO2 and auxiliary measurement capabilities. It also provides a status update of activities and dedicated studies currently undertaken to prepare for the implementation of the space component of this monitoring system.
The Methane Total Column Product from TROPOMI Observations of the Copernicus Sentinel-5 Precursor Mission: Recent Results
Landgraf, Jochen (1); Borsdorff, Tobias (1); aan de Brugh, Joost (1); Lorente, Alba (1); Hasekamp, Otto (1); Butz, Andre (2); Sha, Mahsesh K. (3); Langerock, Bavo (3); Feist, Dietrich (4); Birk, Manfred (5); Wagner, Georg (5) - 1: SRON Netherlands Institute for Space Research, Netherlands, The; 2: University Heidelberg, Germany; 3: Royal Belgian Institute for Space Aeronomy (BIRA-IASB), Brussels, Belgium; 4: Max Planck Institute for Biogeochemistry, Jena, Germany; 5: German Aerospace Center (DLR), Oberpfaffenhofen, Germany
The Tropospheric Monitoring Instrument (TROPOMI) was successfully launched as single payload of ESA’s Sentinel-5 Precursor (S5P) mission on October 13th, 2017. The instrument observes Earth reflected radiances from the ultraviolet to the shortwave infrared spectra range with daily global coverage and with a spatial resolution of 7x7 km2. The telluric absorption around 2.3 μm provides information on the total column amount of methane where the operationally data are processed with the RemoTeC full-physics retrieval algorithm, developed by SRON. In this work, we present recent results on the S5P methane product inferred from nearly one year of TROPOMI measurements. We discuss the use of different data bases for molecular absorption cross sections of water vapor and methane including the recent data of ESA’s SEOM-Improved Atmospheric Spectroscopy Databases (IAS) project. Moreover, for selected TCCON sites we apply our retrieval algorithm to radiometric measurements of the Fourier Transform Spectrometers at the ground site and compare the results with the TCCON and TROPOMI methane product to better understand differences between the data products. Finally, the comparison of the methane S5P product with the proxy methane product from the Japanese GOSAT satellite complements the study.
The Potential for Retrieval of δ13C Methane from Sentinel-5P TROPOMI and Sentinel 5 UVNS
Malina, Edward (1); Hu, Haili (2); Landgraf, Jochen (2); Veihelmann, Ben (1) - 1: ESA/ESTEC, the Netherlands; 2: SRON Netherlands Institute for Space Research, the Netherlands
The recent launch of Copernicus Sentinel-5P (S5P), with its TROPOspheric Monitoring Instrument (TROPOMI) and the future launch of Sentinel 5 (S5), with its Ultraviolet, Near Infrared, Shortwave Infrared (UVNS) instrument will allow for daily global measurements of methane (amongst other atmospheric constituents). In order to enhance the understanding of its sources and sinks and to monitor trends of atmospheric abundances. S5P and S5 aim to aid in the global documentation of methane localized sources, which may have been missed up until now due to lack of, or sparse measurements. Determining the nature of these sources (i.e. whether the source is biological in origin, such as wetlands, or non-biological, such as industrial burn off), could provide additional context to S5P and S5 retrievals, and greatly improve knowledge of the global methane budget. It has been shown (Schwietzke et al., 2016) that the nature of methane sources can be determined through a metric known as δ13C, which is the ratio of its primary isotopologues, 12CH4 (~98% of atmospheric methane) and 13CH4 (~1.1%).
In this study, we investigate the potential for calculating the δ13C ratio from S5P and S5 retrievals, through Information Content analysis techniques (Rodgers, 2000). This study is based on synthetic spectra, calculated from a global ensemble of atmospheric conditions, designed to simulate a wide range of atmospheric and surface conditions over the course of a year. We then perform retrievals of 12CH4 and 13CH4 on these synthetic spectra using the RemoTeC algorithm, assuming the SWIR3 band from S5P/TROPOMI (2305 – 2385 nm) and the SWIR1 band from S5/UVNS (1590 – 1675 nm), where TROPOMI only contains the SWIR3 band, and S5/UVNS contains both SWIR1 and SWIR3. We investigate both bands since SWIR3 contains the most spectral lines, but SWIR1 has higher SNR. For spectroscopy we used the HITRAN 2012 database.
We find that for both spectral bands, assuming a non-scattering atmosphere through the “proxy” technique (Parker et al., 2011), that there is typically enough information content to calculate the δ13C ratio (Degrees of Freedom of Signal > 1). This is true over a wide range of atmospheric conditions, including tropical, arid and desert regions, however high latitude regions show lower information content due to high solar zenith angles. Retrieval errors of less than 10‰ can be achieved with sufficient spatial and/or temporal averaging, with the SWIR1 band showing lower retrieval errors than the SWIR3 band. Additional investigations are performed to establish the sensitivity of the retrieved trace gases to expected systematic errors in the prior knowledge of the RemoTeC algorithm.
IASI Methane Retrievals from the 7.9 and 3.7 Micron Spectral Regions
Knappett, Diane (1,2); Siddans, Richard (1,2); Kerridge, Brian (1,2) - 1: STFC RAL Space, Didcot, United Kingdom; 2: National Centre for Earth Observation (NCEO), Leicester, United Kingdom
The RAL Remote Sensing Group has developed an optimal estimation scheme to retrieve global height-resolved information on methane from IASI using the 7.9 micron band and produced a v1 mission dataset for MetOp-A (R. Siddans et al., 2017, https://doi.org/10.5194/amt-10-4135-2017). This scheme has subsequently been improved through use of pre-retrieved temperature, water vapour and surface spectral emissivity from IASI, MHS and AMSU.
The methane band at 3.7 microns is also observed by IASI. At this wavelength, the terrestrial Planck function is more sensitive to temperature than at 7.9 microns, and on the dayside of the orbit there can also be a significant surface-reflected solar component to top-of-atmosphere spectral radiances. The 3.7 micron band therefore offers the potential to add information on methane in the near-surface layer, where temperature contrast between the surface and atmosphere is low, which limits sensitivity in the 7.9 micron band.
In this paper, we present results from a v2 mission dataset, based on the improved 7.9 micron scheme, as well as results from simulations and test retrievals combining the 3.7 and 7.9 micron bands in comparison to the established 7.9 micron retrieval scheme. An update is also provided on the status of IASI methane processing via the RAL-RSG MetOp NRT chain.
Upper Tropospheric and Stratospheric Trends of Greenhouse Gases as Derived from MIPAS Observations
Stiller, Gabriele P. (1); Plieninger, Johannes (1); Chirkov, Maksym (1); Eckert, Ellen (1,2); Glatthor, Norbert (1); Haenel, Florian (1); Kellmann, Sylvia (1); Laeng, Alexandra (1); von Clarmann, Thomas (1) - 1: Karlsruhe Institute of Technology, Germany; 2: University of Toronto, Ontario, Canada
MIPAS on Envisat measured a large number of greenhouse gases (GHGs) in the upper troposphere and stratosphere during its mission lifetime from July 2002 to April 2012. Among these greenhouse gases are H2O, O3, N2O, CH4, CFC-11, CFC-12, HCFC-22, CCl4, and SF6. We have analysed the trends and shorter-scale variability of the GHGs as a function of altitude and latitude and have related their variations to the seasonal cycle, QBO impact and, in some cases, to solar variability and ENSO. We have also derived the linear trends over the 10-years mission lifetime depending on altitude and latitude. All GHGs show a similar trend pattern with a dipole structure in the two hemispheres. We trace this pattern back to a shift of the stratospheric mean circulation to the South that is manifested as a shift of the latitudinal positions of the subtropical mixing barriers. In order to overcome the complication in trend assessment due to the large variability of trends in the stratosphere, we have developed a method to derive the trend at the entry point to the stratosphere. We discuss the implication of greenhouse gas trends varying with altitude for the vertically non-resolving monitoring of greenhouse gases.
First Detection Of CH4 Point Sources From Space Using TROPOMI S5P
Aben, Ilse (1); Pandey, Sudhanshu (1); Hu, Haili (1); Borsdorff, Tobias (1); Sadavarte, Pankaj (1); Denier Van Der Gon, Hugo (3); Dekker, Iris (1,4); Gautam, Ritesh (2); Hasekamp, Otto (1); Landgraf, Jochen (1); Houweling, Sander (1,5) - 1: SRON, Netherlands, The; 2: EDF, USA; 3: TNO, Netherlands; 4: IMAU, Netherlands; 5: VU, Netherlands
Sentinel-5P was successfully launched in October 2017 with on-board its single payload instrument TROPOMI. TROPOMI is a push-broom spectrometer measuring various trace gases amongst which methane. Methane is the second most important anthropogenic greenhouse gas after CO2, but on a per molecule basis methane is a much more potent GHG compared to CO2. In addition, because of its much shorter lifetime in the atmosphere reduction of its emissions have already effect on the short term, making it an interesting target for climate change mitigation action which has been recognized by many policy makers.
The potential of detecting 'point sources' of methane and quantifying its emissions from space has been demonstrated by studies on SCIAMACHY and GOSAT data. With TROPOMI we aim to make a next step in this field as TROPOMI CH4 measurements have unprecedented high spatial resolution (7 x 7 km2) combined with daily global coverage. This is very important as we can only use cloud-free observations which effectively means we can only use a few percent of the data. In this presentation we will show a few first examples of methane 'point sources' observed with TROPOMI including preliminary estimates of emissions. One of the events is a major accidental gas blow-out in a Gas & Oil facility.
16:10 - 18:00
TanSat First Results and Chinese Terrestrial Biospheric CO2 Fluxes inversion From GOSAT and OCO-2
Liu, Yi (1); Wang, Jing (1); Yang, Dongxu (1); Feng, Liang (2); Palmer, Paul (2); Boesch, Hartmut (3) - 1: Institute of Atmospheric Physics，Chinese Academy of Science, China, People's Republic of; 2: National Centre for Earth Observation, University of Edinburgh, UK; 3: National Centre for Earth Observation, University of Leicester, UK
Chinese carbon dioxide observation satellite (TanSat) launched in 22 Dec 2016, after on-broad test and calibration, TanSat starts to record the back-scattered sunlight spectrum from scientific earth observation and produced XCO2 data from February 2017.
First, the preliminary results of XCO2 retrieved from TanSat measurements will be presented, and inter-compared with OCO-2 results will be discussed. Validation study with TCCON measurements indicate a better than 2.2 ppm with 8 stations. The first global CO2 map represented a milestone in Chinese GHGs satellite. TanSat will release level 2 and higher level products to support carbon emission estimations and climate change studies.
Second, we use an atmospheric inversion to estimate the magnitude and distribution of land biosphere CO2 fluxes over China, the satellite observations of GOSAT, OCO-2 are applied to verify our a posteriori fluxes.
The OCO-3 Mission: Global Observations of CO2 and Solar-Induced Fluorescence from the International Space Station – Science Objectives and Instrument Performance
Kurosu, Thomas P; Eldering, Annmarie; Pavlick, Ryan P; Fisher, Brendan M; Osterman, Gregory B - Jet Propulsion Laboratory/California Institute of Technology, United States of America
The Orbiting Carbon Observatory 3 (OCO-3) will continue global CO2 and solar-induced chlorophyll fluorescence (SIF) using the flight spare instrument from OCO-2. The instrument has been through ground testing and thermal vacuum, and will be packaged for installation on the International Space Station (ISS), currently scheduled for launch in February 2019. This talk will focus on the science objectives, science data products, early operations plan, and a few highlights from the instrument performance tests.
The low-inclination ISS orbit lets OCO-3 sample the tropics and sub-tropics across the full range of daylight hours with dense observations at northern and southern mid-latitudes (+/- 52º). The combination of these dense CO2 and SIF measurements provides continuity of data for global flux estimates as well as a unique opportunity to address key deficiencies in our understanding of the global carbon cycle. The instrument utilizes an agile, 2-axis pointing mechanism (PMA), providing the capability to look towards the bright reflection from the ocean and validation targets. In addition to the nadir-, glint-, and target-mode geometries familiar from OCO-2, OCO-3 includes a new observation mode dedicated to mapping out larger spatial-scale emitters like cities. This Snapshot Area Map (SAM) mode will be used to map areas of up to 100x100 km2 on the Earth surface with the standard OCO-3 ground footprints of 2x3 km2, providing unprecedented high spatial resolution coverage of large-scale CO2 emitters worldwide. Measurements over urban centers could aid in making estimates of fossil fuel CO2 emissions. Similarly, the snapshot mapping mode can be used to sample regions of interest for the terrestrial carbon cycle. In addition, there is potential to utilize data from the currently operating ISS instruments ECOSTRESS (ECOsystem Spaceborne Thermal Radiometer Experiment on Space Station) and GEDI (Global Ecosystem Dynamics Investigation), which measure other key variables of the control of carbon uptake by plants, to complement OCO-3 data in science analysis.
Detailed simulations of planned operations and data quality have been completed and will be reported along with the final instrument characterization from thermal vacuum testing. The specific nature of the ISS orbit track produces spatial and temporal coverage that is something of a paradigm shift compared to low-earth-orbiting satellites like OCO-2, which provide observations at fixed overpass times and repeat cycles. OCO-3 observations will necessitate re-evaluation and adaptation of the current approaches of how satellite data are being used in model evaluation and science studies.
Performance Estimations for a Future Greenhouse Gas Monitoring Mission using an End-to-End Simulator System
Noël, Stefan (1); Reuter, Max (1); Bramstedt, Klaus (1); Bovensmann, Heinrich (1); Burrows FRS, John P. (1); Hintze, Christian (2); Sturm, Philipp (2); Acarreta, Juan (3); Marshall, Julia (4); Jurado, Pedro (5); Löscher, Armin (5); Meijer, Yasjka (5) - 1: IUP University of Bremen, Germany; 2: Airbus Defence and Space GmbH, Immenstaad, Germany; 3: DEIMOS Space S.L.U., Madrid, Spain; 4: Max Planck Institute for Biogeochemistry, Jena, Germany; 5: ESA/ESTEC, Noordwijk, The Netherlands
Greenhouse gas (GHG) measurements are of increasing importance to understand the evolving carbon cycle in the Anthropocene and for policy makers aiming to limit manmade climate change. Based on the research in the development of the Earth Explorer 8 CarbonSat Phase A/B1 activities and in preparation for a forthcoming CO2 monitoring mission within the European COPERNICUS program, an end-to-end (E2E) mission performance simulation system for GHG total column products has been successfully developed, implemented, tested and used. This mission E2E simulator is able to reproduce all significant processes, design and steps that impact the mission performance as well as output simulated data products in the aim to become a coherent test bed for L1PP and L2PP and to support the verification of space segment performance and associated sensitivity analysis.
The GHG total column performance simulator (GHG-TCPS) comprises geometry, scene, orbit, instrument, Level 1b processing and up to Level 2 simulation modules, all embedded in an OpenSF framework infrastructure. The GHG-TCPS aims at deepening the understanding of the expected performance of a GHG observation mission focusing on CO2 and CH4 based on detailed observation system simulations (OSS). It includes the simulation of realistic large-scale full swath 2D scenes, which requires sophisticated instrument and retrieval simulation modules to be implemented in a consistent way.
The GHG-TCPS system has been used to run a series of simulations to estimate the performance of a GHG imaging spectrometer system to measure CO2 and CH4 total column content for extended areas, city scale and point scale plumes.
In this study we describe briefly the GHG end-to-end performance simulation system and present results from simulations using realistic atmospheric scenarios. These include examples of the application for flux inversion for selected source regions. These results enable the performance of the future CO2 observing system to be assessed realistically up to Level 4 data products.
Use of NO2 and CO Observations to Estimate CO2 Emissions of Cities and Power Plants with a Constellation of CO2 Satellites
Kuhlmann, Gerrit (1); Clément, Valentin (2); Fuhrer, Oliver (3); Marshall, Julia (4); Broquet, Grégoire (5); Meijer, Yasjka (6); Löscher, Armin (6); Brunner, Dominik (1) - 1: Empa, Swiss Federal Laboratories for Materials Science and Technology, Dübendorf, Switzerland; 2: Center for Climate System Modelling (C2SM), ETH Zürich, Zürich, Switzerland; 3: MeteoSwiss, Federal Office of Meteorology and Climatology, Zürich, Switzerland; 4: Max Planck Institute for Biogeochemistry, Jena, Germany; 5: LSCE, Laboratoire des sciences du climat et de l’environnement, Paris, France; 6: ESA/ESTEC, Noordwijk, the Netherlands
The European Commission is currently considering expansion of the space component of the Copernicus programme with a constellation of CO2 imaging spectrometers to support the global monitoring of CO2 emissions. The CO2 instruments would allow for the observation of CO2 plumes from individual point sources such as large cities and power plants and the quantification of their emissions. However, since the CO2 signals of plumes can be weak and obscured by biospheric signals, measurements of auxiliary trace gases such as CO and NO2 were proposed to help detect the plume and separate anthropogenic from biospheric signals.
We present results from the SMARTCARB study which assessed the potential synergies of CO and NO2 measurements for detecting and quantifying CO2 point sources. For the study, we simulated highly realistic CO2, CO and NO2 fields (1×1 km2 resolution) with the COSMO-GHG model for the year 2015. The model domain covered the city of Berlin and several power plants. The simulations were used to generate synthetic XCO2, CO and NO2 satellite observations (2×2 km2 pixel size with 250-km swath) for constellations of up to six satellites. The CO2 plumes of Berlin and the power station Jänschwalde were detected using either CO2, CO or NO2 observations, and their CO2 emissions were quantified by different methods.
Although a constellation of six satellites was sufficient to cover Berlin on a daily basis, only about 60 out of 365 plumes per year could be observed due to frequent cloud cover. The CO2 instrument could detect only 6-14 plumes of these 60 plumes with high (σVEG50 = 1.0 ppm) and low noise (σVEG50 = 0.5 ppm), respectively, because the CO2 signals were often too weak. A CO instrument performed worse than the CO2 instrument, while the number of detectable plumes could be significantly increased to 39 plumes with an NO2 instrument, assuming instrument specifications similar to Sentinel-5P. The NO2 instrument also greatly helped to quantify the background XCO2 levels required to quantify the local enhancement within the plumes. The CO2 instrument alone could only detect a small fraction of the real plume, so that the background, estimated from the values surrounding the plume, contained significant amounts of XCO2 emitted from Berlin. Consequently, the XCO2 background was overestimated and Berlin's emissions were correspondingly underestimated by about 15-25%. The NO2 instrument detected a much larger portion of the plume and therefore enabled an almost unbiased estimation of the background and the emissions of the city (<10%). The uncertainties of estimated emissions for single overpasses were about 5-10 Mt yr-1 (30%-60%) and, for a constellation of six satellites, the RMSDs of the annual mean estimate were 4-7 Mt yr-1 for the CO2 instrument and about 2 Mt yr-1 when also using the NO2 instrument.
In conclusion, an NO2 instrument on the same platform as a CO2 instrument significantly improves the capability of estimating CO2 emissions from cities and power plants by increasing the number of detectable plumes and by reducing the bias and scatter of the estimated emissions.
Estimation of CO2 Fluxes from Localized Anthropogenic Emission Sources Using Co-located OCO-2 CO2 and S5P NO2 Observations
Reuter, Max; Buchwitz, Michael; Schneising, Oliver; Krautwurst, Sven; Richter, Andreas; Bovensmann, Heinrich; Burrows, John - University of Bremen, Germany
Carbon dioxide (CO2) is the most important anthropogenic greenhouse gas and monitoring its emissions from space has become an important objective of (potential) future satellite missions such as the planned European anthropogenic CO2 monitoring mission or NASA’s GeoCarb mission.
CO2 is long lived and well mixed in the atmosphere. Globally, its natural gross fluxes are much larger than anthropogenic emissions. This makes it challenging to detect and analyze plumes of individual point sources in satellite measurements of the CO2 column-average dry-air mole fraction (XCO2).
In populated and industrialized areas, the largest part of tropospheric NO2 originates from the co-emission with CO2 during the combustion of fossil fuels, e.g., by power plants, traffic, and domestic heating. NO2 has a short lifetime in the order of hours, so that its vertical column densities often exceed background levels by orders of magnitude near sources. This makes it a suitable tracer of recently emitted anthropogenic CO2, i.e. close to the source before the CO2 plumes blend into background concentrations.
In this presentation we use NO2 measurements made by the S5P satellite to help to locate the anthropogenic CO2 plumes in co-located XCO2 measurements of the OCO-2 satellite, close to sources. Due to OCO-2’s narrow swath, it usually measures only a cross section of the plume. We estimate the cross sectional CO2 flux utilizing ECMWF ERA5 wind information and discuss the results and potential source attributions by taking into account the extended NO2 plume structures observable in S5P’s wide swath.
The first year of TROPOMI Carbon Monoxide retrievals: An assessment and perspective for future research.
Borsdorff, Tobias (1); aan de Brugh, Joost (1); Pandey, Sudhanshu (1); Aben, Ilse (1); Houweling, Sander (2); Hasekamp, Otto (1); Kumar Sha, Mahesh (3); Langerock, Bavo (3); Landgraf, Jochen (1) - 1: SRON Netherlands Institute for Space Research, Utrecht, Netherlands; 2: Vrije Universiteit Amsterdam, Amsterdam, Netherlands; 3: Royal Belgian Institute for Space Aeronomy (BIRA-IASB), Brussels, Belgium
The Tropospheric Monitoring Instrument (TROPOMI) was launched on 13th of October on ESA’s Sentinel-5 Precursor satellite. For almost one year the instrument performs measurements of the ultraviolet, visible, near-infrared and shortwave infrared spectral band from space in nadir observation geometry. SRON Netherlands Institute of Space Research developed and supports the SICOR retrieval algorithm for the operational processing of the TROPOMI CO total column product. Already during the early phase of the mission, comparisons of the CO product with ECMWF-IFS model simulations and collocated TCCON and NDACC ground-based measurements demonstrated a data quality well within the mission requirements (accuracy <15%, precession < 10%), which led to a data release for public usage in July 2018. In this contribution, we summaries the findings of the first year of TROPOMI CO measurements and give a perspective for future research. We demonstrate the capability of TROPOMI to detect CO enhancements by recent fire events and to track anthropogenic CO pollution on the global scales. Based on selected cases, the emissions of pollution hot spots like cities and industrial areas are quantified and interpreted by means of dedicated simulations of the CO atmospheric transport using the regional Weather Research and Forecasting Model (WRF). Finally, we report on the long-term perspective to further improve the quality of the TROPOMI CO dataset.
The Monitoring Nitrous Oxide Sources (MIN2OS) satellite project
Ricaud, Philippe (1); Attie, Jean-Luc (2); Brooker, Laure (3); Emili, Emanuele (4); Granier, Claire (2); Lahoz, William (5); Lelieveld, Jos (6); Leonard, Joel (7); Nevrly, Vaclav (8); Papale, Dario (9); Pasternak, Frederic (3); Pattey, Elizabeth (10); Piacentini, Andrea (4); Ramonet, Michel (11); Raynal, Helene (7); Saitoh, Naoko (12); Sciare, Jean (13); Tallec, Tiphaine (14); Warner, Juying (15); Zelinger, Zdenek (16) - 1: CNRM, France; 2: Laboratoire d’Aérologie, France; 3: Airbus Defence and Space, France; 4: CERFACS, France; 5: NILU, Norway; 6: MPI, Germany; 7: INRA, France; 8: Ostrava University, Czech Republic; 9: University of Tuscia, Italy; 10: Agriculture and Agri-Food Canada, Canada; 11: LSCE, France; 12: Chiba University, Japan; 13: The Cyprus Institute, Cyprus; 14: CESBIO, France; 15: Maryland University, USA; 16: J. Heyrovsky Institute of Physical Chemistry, Czech Republic
The Monitoring Nitrous Oxide Sources (MIN2OS) satellite project submitted to the European Space Agency (ESA) Earth Explorer 10 (EE10) aims to monitor nitrous oxide (N2O) sources on a global scale by inverting surface fluxes from N2O space-borne measurements sensitive in the lowermost atmospheric layers. Through this approach, the MIN2OS project will provide high-resolution (10´10 km) emission inventories of N2O that contribute to quantify the Earth’s radiative forcing at global scale and on a daily to monthly basis depending on the applications (agricultural sector, stakeholders, policy makers, academic research oriented). Our novel approach is based on the development of 1) a space-borne instrument operating in the Thermal InfraRed (TIR) domain inherited from a more sensitive version of the Infrared Atmospheric Sounding Interferometer (IASI) and the Infrared Atmospheric Sounding Interferometer-New Generation (IASI-NG) instruments, providing N2O mixing ratio in the lowermost atmosphere (800-900 hPa) and 2) an inversion source model to estimate, from atmospheric satellite observations, N2O surface fluxes.
Nitrous oxide is a greenhouse gas (GHG) that has an overall radiative forcing 10 times weaker than thus of carbon dioxide (CO2). The emissions of N2O mainly come from natural sources (55-61%) and the remaining from anthropogenic activities (agricultural and industrial sectors). The N2O emissions and sources are highly uncertain both over land and ocean. Specific difficulties need to be overcome in monitoring the N2O sources at global scale and high resolution: sensitivity of the measurements in the lowermost troposphere, sparse surface measurements, large modelling and source inversion uncertainties, high temporal and spatial variability of the N2O surface fluxes.
To fulfil the MIN2OS objectives, a new TIR instrument will be developed, centred on the N2O band at 1240-1320 cm-1, with a resolution of 0.125 cm-1, a Full Width at Half Maximum of 0.25 cm-1 and a swath of 300 km. It will be on-board a platform at ~830 km altitude crossing the Equator in descending node at 09:30 local time (LT) in synergy with the two following operational platforms in 2028: 1) in time and space coincidence with Metop-SG 2A that will contain IASI-NG to use surface properties and vertical profiles of atmospheric constituents and temperature to optimally constrain the retrieval of N2O vertical profiles and 2) with Sentinel 2 to use surface information at the field scale (land occupation and use) with no need for synchronization. The expected lifetime of the MIN2OS project to be launched in 2028 is 4-5 years. The spectral noise could be decreased by a factor 3 to 5 compared to thus of the IASI-NG and the Greenhouse gases Observing SATellite-2 (GOSAT-2) missions. With MIN2OS, N2O can be obtained from 3 separate atmospheric layers: around 800-900 hPa (specific to MIN2OS), around 500 hPa (like IASI-NG and GOSAT-2) and around 300 hPa (like IASI, IASI-NG and GOSAT-2). The N2O total error is expected to be ~1% (3-4 ppbv) along the vertical.
08:30 - 10:20
The Operational Sentinel-5 Precursor Geophysical Products and Perspectives for Sentinel-4
Loyola, Diego (1); Veefkind, Pepijn (2); Landgraf, Jochen (3); Van Roozendael, Michel (4); Richter, Andreas (5); Siddans, Richard (6); Wagner, Thomas (7); Tamminen, Johanna (8); Aben, Ilse (3); Lambert, Jean-Christopher (4); Heue, Klaus-Peter (1); Lerot, Chistophe (4); Zimmer, Walter (1); Romahn, Fabian (1); Balis, Dimitris (9); Verhoelst, Tijl (4); Koukouli, Maria-Elissavet (9); Garane, Katerina (9); ter Linden, Mark (2); Keppens, Arno (4); Tuinder, Olaf (2); Pedergnana, Mattia (1); Hubert, Daan (4); Eskes, Henk (2); Eichmann, Kai-Uwe (5); Compernolle, Steven (4); Valks, Pieter (1); Theys, Nicolas (4); Hedelt, Pascal (1); De Smedt, Isabelle (4); Chan, Ka Lok (1); Borsdorff, Tobias (3); Langerock, Bavo (4); Hu, Haili (3); Argyrouli, Athina (1); Sneep, Maarten (2); Lutz, Ronny (1); Wang, Ping (2); Stein Zweers, Deborah (2); de Graaf, Martin (2); Smith, Andy (6); Kujanpää, Jukka (8); Huan, Yu (4); Cheng, Zhibin (1); Dehn, Angelika (10); Zehner, Claus (10) - 1: German Aerospace Center (DLR), Germany; 2: Royal Netherlands Meteorological Institute (KNMI), The Netherlands; 3: Netherlands Institute for Space Research (SRON), The Netherlands; 4: Institute for Space Aeronomy (BIRA-IASB), Belgium; 5: Institute of Environmental Physics (IUP Bremen), Germany; 6: STFC, Rutherford Appleton Laboratory (RAL), U.K; 7: Max Planck Institute for Chemistry (MPIC), Germany; 8: Max Planck Institute for Chemistry (MPIC), Germany; 9: Aristotle University of Thessaloniki (AUTH), Greece; 10: ESA/ESRIN, Italy
The Sentinel-5 Precursor (S5P) mission, launched in October 2017, started the operational atmospheric composition measurements from space as part of the European Copernicus programme. The payload of the S5P mission is the TROPOspheric Monitoring Instrument (TROPOMI) that provides key information on air quality, climate and the ozone layer with high spatial resolution and daily global coverage.
In this presentation we provide an overview of the operational TROPOMI geophysical products including O3, NO2, SO2, HCHO, CO, CH4, as well as UV, cloud and aerosol properties.
The European teams responsible for the operational products are organized in three groups covering: (i) retrieval algorithms, (ii) data processors being used in the S5P ground-segment for the generation of the operational TROPOMI products, and (iii) routine validation of S5P products using fiducial reference measurements. It is planned to maintain this project organization during the complete mission in order to ensure the timely provision of state-of-science data products that are continuously improved and validated.
Initial versions of the TROPOMI products were already available a few weeks after launch and were presented at the first light event that took place in December 2017. The retrieval algorithms and data processors were optimized during the commissioning phase that lasted until April 2018 and the results of the preliminary validation were presented in June 2018. Finally the first set of operational S5P products was released to the public in July 2018. The release of the remaining S5P products is organized in a staggered approach and will take place during the second part of 2018 and early 2019.
The work on TROPOMI/S5P geophysical products is funded by EU Copernicus, ESA and national contributions from The Netherlands, Germany, Belgium and Finland.
Total and Tropospheric ozone columns from Sentinel-5P
Heue, Klaus-Peter (1); Valks, Pieter (1); Xu, Jian (1); Loyola, Diego (1); Lerot, Christophe (2); Van Roozendael, Michel (2) - 1: DLR, German Aerospace Center, Germany; 2: IASB-BIRA Belgian Institute for Space Aeronomy, Belgium
In October 2017, the Sentinel-5P satellite with the TROPOMI instrument was launched into space. Total ozone columns from TROPOMI instrument are retrieved in near real time using the well established DOAS approach, and a subsequent conversion into vertical column densities using an iterative air mass factor calculation. The total ozone algorithm has already been successfully applied to the GOME, SCIAMACHY and GOME-2 missions. To account for the high spatial resolution of the TROPOMI instrument, the treatment of clouds in the total ozone retrieval has been improved.
Besides the total column, a tropospheric ozone column is also provided from TROPOMI. The cloud convective differential method is used to separate the tropospheric and stratospheric ozone column. Deep convective clouds shield the tropospheric ozone from the satellite based observers. Therefore the ozone columns above deep convective clouds are good approximations of the stratospheric ozone column. These data are corrected for the variety in the cloud top altitudes and averaged over a 5 days time period and a clean area. In a last step the stratospheric column are subtracted from the total ozone columns for cloud free observations.
After a short introduction to the retrieval algorithms, first results will be presented for both total and tropospheric ozone columns from TROPOMI. First comparisons to ozone column data from GOME-2 and ground-based observations will be shown as well.
Sentinel-5P TROPOMI Tropical Upper Tropospheric Ozone Volume Mixing Ratios using the Cloud Slicing Technique: Advantages of a Spatially High-Resolution Instrument
Eichmann, Kai-Uwe; Weber, Mark - University of Bremen, Germany
The TROPOspheric Monitoring Instrument (TROPOMI), on board the Sentinel 5 precursor (S5p) satellite, was launched in October 2017. A first set of products, for instance, ozone and cloud properties, became publicly available in July 2018.
Using this operational S5p ozone and cloud dataset, we derive tropical upper tropospheric ozone volume mixing ratios (TTCO). For this, we employ the cloud slicing method [Ziemke, 2001] and compare our results of the cloud slicing algorithm (CSA) with data from the operational CSA version.
The TROPOMI instrument has a high spatial resolution and a daily coverage of the Earth. We will discuss the choice of the best temporal and spatial resolution that is optimally suited for the intrinsic statistical usage of ozone and cloud measurements for the CSA method. This strongly depends on the instrument characteristics.
The work on TROPOMI/S5P geophysical products is funded by ESA and national contributions from the Netherlands, Germany, Belgium, and Finland.
Merging of Ozone Profiles From SCIAMACHY, OMPS and SAGE II Observations to Study Long-term Stratospheric Ozone Changes
Arosio, Carlo; Rozanov, Alexei; Burrows, John P. - Institute of Environmental Physics, University of Bremen, Bremen, Germany
A continuous monitoring of the stratospheric ozone layer over a global scale is done by means of several techniques. Observations in limb geometry from satellite platforms provide ozone profiles with a good vertical resolution, spatial and temporal coverage.
SCIAMACHY and OMPS-LP are two satellite instruments able to collect shortwave scattered radiance in limb geometry. Ozone profile data sets from SCIAMACHY (2002-2012) and OMPS-LP (2012-2018) were created at the University of Bremen using the same radiative transfer model, spectroscopic databases and a similar retrieval algorithm. The aim of this study is the merging of these data sets, to obtain a consistent time series of ozone global distributions. Since the two missions overlap only for 3 months, a transfer function is needed to overcome issues related to the sensors calibration. To this aim, we chose measurements performed by the MLS instrument as a reference: this sensor has been collecting atmospheric emission in the microwave spectral region in limb geometry since 2004.
Monthly latitude- and longitude-resolved time series of ozone profiles were calculated for the two instruments, exploiting the high spatial resolution of the data sets. Their merging has been then performed minimizing the differences between OMPS-LP and SCIAMACHY ozone number density profiles with respect to MLS values, for each latitude, longitude and altitude independently. The seasonal cycle was not subtracted, because it was found to be consistent enough among the three instruments. Short-term changes in ozone profiles were calculated over 2003-2018 using a multilinear regression (MLR) analysis, including fit proxies as QBO, ENSO and a solar forcing. Positive trends were detected between 35 and 45 km at mid-latitudes, with an increasing ozone concentration up to 2-3% per decade. Negative changes were found in the lower tropical stratosphere but statistically non-significant. A comparison with short-term trends calculated over the SCIAMACHY time period has been done: while a general agreement was found, some discrepancies were seen in the tropical mid-stratosphere.
A merging with SAGE II ozone profiles was also performed: zonal monthly anomalies from the 3 instruments are merged to study ozone trends over the last 35 years. Applying the same MLR analysis, consistent results with previous studies were found: negative trends before 1997 up to -6% per decade at mid-latitudes around 40 km and the expected recovery after to ozone turn-around point at the end of ‘90, related also to the implementation of the Montreal protocol and its amendments.
Ozone Decline in the Tropical Mid-stratosphere Observed by SCIAMACHY and Its Relation to the Stratospheric Dynamics
Galytska, Evgenia (1,2); Rozanov, Alexey (1); Chipperfield, Martyn P. (3,4); Dhomse, Sandip. S. (3); Weber, Mark (1); Arosio, Carlo (1); Feng, Wuhu (3,5); Burrows, John P. (1) - 1: Institute of Environmental Physics, University of Bremen, Bremen, Germany; 2: Department of Meteorology and Climatology, Taras Shevchenko National University of Kyiv, Kyiv, Ukraine; 3: School of Earth and Environment, University of Leeds, Leeds, UK; 4: National Centre for Earth Observation, University of Leeds, Leeds, UK; 5: National Centre for Atmospheric Science, University of Leeds, Leeds, UK
As shown by recent studies, global atmospheric Ozone (O3) has begun to recover resulting from the decline in the atmospheric abundance of anthropogenic emissions of halogenated Ozone Depleting Substances (ODS), which is achieved by signing in 1987 Montreal Protocol (and its amendments). Nevertheless, there are other factors that also affect the temporal changes of O3, such as non-halogen chemical species, solar impact, natural forcings in changing climate, volcanic activities implying significant aerosol loading etc. Therefore, stratospheric O3 is expected to vary within different timescales as a result of dynamical and chemical forcings.
Contrary to the overall recovery of the global O3, an unexpected O3 decline in the tropical mid-stratosphere was observed from the SCanning Imaging Absorption SpectroMeter for Atmospheric CHartographY (SCIAMACHY) measurements during 2004-2012. Similar negative changes of O3 were also observed from other satellite measurements: HALOE (1991-2005), combined SAGE II-GOMOS (1997-2011), MIPAS (2002-2012), MLS (2004-2013). Our analysis of SCIAMACHY measurements shows that the decrease in O3 is accompanied by an increase in NO2.
To reveal the causes of O3 and NO2 changes, we performed simulations with the TOMCAT 3D Chemistry Transport Model (CTM) with different chemical and dynamical forcings. TOMCAT reproduces the SCIAMACHY-observed O3 and NO2 changes in the tropical mid-stratosphere. The model simulations show that the positive changes in NO2 (around 7% per decade) are due to similar positive changes in reactive odd nitrogen (NOy), which are a result of a longer residence time of the source gas N2O. As the global atmospheric lifetime of N2O exceeds 100 years, its negative changes of 10% per decade can be described by variations in dynamics in the deep branch of Brewer-Dobson Circulation. However, modelled annual mean age-of-air (AoA) did not show any significant changes in the transport in the tropical mid-stratosphere during 2004-2012. Further analysis of model results demonstrated significant seasonal variations: positive AoA changes, which indicate transport slowdown during autumn months (September-October), cause longer residence time of N2O with more intense NOy production which effectively depletes O3; and negative AoA changes during winter months (January, February), which indicate more intense N2O transport, with shorter residence time of N2O and less intense NOy production via N2O + O(1D) to further destroy O3. Although the changes in AoA cancel out when averaging over the year, the N2O change remains due to non-linearities in the chemistry-transport interactions.
Ozone Profile Retrievals Using SCIAMACHY Level-1 Version 9 Nadir Measurements
Wang, Ping; Tuinder, Olaf; Stammes, Piet - Royal Netherlands Meteorological Institute, Netherlands, The
We have retrieved nadir ozone profiles using SCIAMACHY Level-1 version 9 data with the Ozone ProfilE Retrieval Algorithm (OPERA) developed at KNMI. The v9 data is supposed to be the last version of the SCIAMACHY L1 data. Compared to the nadir ozone profile retrievals performed using v8 and v7 data (Shah et al., 2018), we focus on the degradation correction of the SCIAMACHY measurements. We first applied all calibration options provided in the sciaL1c tool to the L1 v9 spectra. All the analyses are based on the SCIAMACHY L1c child files.
The radiometric degradation of SCIAMACHY Channel 1 and 2 data has been analysed using one day per month of global measurements for the whole mission period (2002-2012). Assuming that the global mean reflectance is relatively stable in the 10-years period, we compared the SCIAMACHY measured reflectances with simulated reflectances using OPERA. It turned out that the degradation of the SCIAMACHY reflectances of wavelengths around 265 nm in Channel 1 amounts to about 30 % in 2012. The degradation of channel 2 is much smaller.
The wavelength calibration and Instrument Spectral Response Function (ISRF) has been analysed for the same SCIAMACHY L1c files using the QDOAS algorithm and our own algorithm. The changes in ISRF and wavelength calibration are very small. These corrections have been taken into accounted in OPERA.
We have processed a selected number of ozone profiles with OPERA taking all these improvements into account. The ozone profiles have been validated with ozonesonde measurements launched at De Bilt. We will show results on the ozone profiles with the latest improvements in the SCIAMACHY data.
Stability Requirements on Long-Term (Satellite) Ozone Observations and their Implication for Trend Detection
Weber, Mark; Rahpoe, Nabiz - University of Bremen, Germany
Drift uncertainties in long-term data records like for many essential climate variables have a large impact on the sensitivity of the data record to detect small trends. A good example is stratospheric ozone which is expected to slowly recovery due to the successful phase-out of ozone-depleting substances (ODS) as regulated by the Montreal Protocol. So far positive ozone trends since 2000 were only statistically significant in the upper stratosphere according to the recent WMO ozone assessment. In addition to the high variability in ozone potential instrumental drifts in satellite data add to trend uncertainty. Stability requirements from 1%/decade (total ozone) to 5%/decade (ozone profiles) have been specified, however, the rationale behind these numbers is not clear. Satellite measurements of ozone are available for nearly four decades. The single lifetime of a typical satellite instrument is on the order of 5-7 years, the longest single instrument record was from SAGE II operating for nearly twenty years. Uncertainties from combining or merging multiple datasets to obtain long-term time series also add to trend uncertainties. The connection between stability requirements and trend detection limits from multiple satellites are quantified by using simple Monte Carlo simulations.
10:50 - 12:35
Development of an Improved-DOAS Algorithm for Fast and Accurate Total Ozone Retrievals
Lerot, Christophe (1); Yu, Huan (1); Theys, Nicolas (1); Fayt, Caroline (1); Van Roozendael, Michel (1); Hedelt, Pascal (2); Heue, Klaus-Peter (2); Loyola, Diego (2); Koukouli, MariLiza (3); Garane, Katerina (3); Balis, Dimitris (3); Smeets, Joost (4); ter Linden, Mark (4) - 1: BIRA-IASB, Belgium; 2: DLR-IMF, Germany; 3: AUTH, Greece; 4: S&T, The Netherlands
Total ozone columns have been routinely retrieved from satellite nadir observations in the Huggins bands for several decades using algorithms in constant evolution. In Europe, DOAS-type algorithms are used for operational processing of total ozone from GOME/ERS-2, SCIAMACHY/Envisat, OMI/Aura and GOME-2/Metop. The DOAS approach is fast and provides good results for most geophysical conditions. However it generally neglects the wavelength-dependence of the effective light path in the fit interval, which can lead to significant biases under conditions of large ozone optical depth. This motivated the development of a direct-fitting algorithm (GODFIT), which provides more accurate results under a wider range of conditions but at the cost of more demanding computational resources. The total ozone direct-fitting algorithm is the baseline for the generation of climate data records within the ESA CCI and Copernicus Climate Change service activities.
We present an improved DOAS-type total ozone algorithm currently developed as part of the level-2 prototype processor project for the future Sentinel-5 mission, which preserves accuracy, while maintaining high computational performance compatible with near-real time processing. The approach uses a Taylor expansion of the O3 slant columns considering their wavelength dependence. In addition, a new iterative molecular Ring correction is implemented, which leads to a substantial reduction of ozone biases. This is combined with a derivation of the effective surface albedo of the observed scene at 340 nm, while air mass factors are pre-computed at the wavelength of 328.2 nm and stored in external LUTs for fast slant-to-vertical column conversion. Random and systematic error estimates are provided on a pixel-per-pixel basis, as well as averaging kernels. We present OMI and TROPOMI ozone datasets derived with this new algorithm and test their accuracy against reference direct-fitting results. Additional validation using independent ground-based Brewer and Dobson data confirm the good performance of the new DOAS retrievals, which show no significant dependence with respect to geophysical parameters such as solar or viewing zenith angle, latitude and cloud parameters.
Operational trace gas column observations from GOME-2 on MetOp
Valks, Pieter (1); Chan, Ka Lok (1); Pinardi, Gaia (2); Hedelt, Pascal (1); Liu, Song (1); Van Roozendael, Michel (2); De Smedt, Isabelle (2); Theys, Nicolas (2); Koukouli, MariLiza (3); Balis, Dimitris (3) - 1: DLR, German Aerospace Center, Germany; 2: IASB-BIRA Belgian Institute for Space Aeronomy, Belgium; 3: Aristotle University of Thessaloniki, Greece
This contribution focuses on the operational GOME-2 trace gas column products developed in the framework of EUMETSAT’s Satellite Application Facility on Atmospheric Composition Monitoring (AC SAF). We present an overview of the retrieval algorithms for ozone, OClO, NO2, SO2 and formaldehyde, and we show examples of various applications such as air quality and climate monitoring, using observations from the GOME-2 instruments on MetOp-A and MetOp-B.
Total ozone and the minor trace gas columns from GOME-2 are retrieved with the GOME Data Processor (GDP), which uses an optimized Differential Optical Absorption Spectroscopy (DOAS) algorithm, with air mass factor conversions based on the LIDORT model. Improved total and tropospheric NO2 columns are retrieved in the visible wavelength region between 425 and 497 nm. SO2 emissions from volcanic and anthropogenic sources can be measured by GOME-2 using the UV wavelength region around 320 nm. For formaldehyde, an optimal DOAS fitting window around 335 nm has been determined for GOME-2.
The use of trace gas observations from the GOME-2 instruments on MetOp-A and MetOp-B for air quality purposed will be illustrated, e.g. for South-East Asia and Europe. Furthermore, comparisons of the GOME-2 satellite observations with ground-based measurements will be shown. Finally, the use of GOME-2 trace-gas column data in the Copernicus Atmosphere Monitoring Service (CAMS) will be presented.
Global Distribution Of Lowermost Tropospheric Ozone Pollution From Multispectral Synergism Of IASI And GOME-2 Satellite Measurements
Cuesta, Juan (1); Costantino, Lorenzo (1); Dufour, Gaëlle (1); Eremenko, Maxim (1); Foret, Gilles (1); Beekmann, Matthias (1); Orphal, Johannes (2); Boonne, Cathy (3); Kanaya, Yugo (4); Takigawa, Masayuki (4); Miyazaki, Kazuyuki (4); Gaudel, Audrey (5); Cooper, Owen (5) - 1: LISA Laboratoire Interuniversitaire des Systèmes Atmosphériques - CNRS/UPEC/UPD, France; 2: IMK/KIT, Karlsruhe, Germany; 3: IPSL/AERIS, Paris, France; 4: JAMSTEC, Yokohama, Japan; 5: NOAA, Boulder, USA
Tropospheric ozone is the most hazardous gaseous pollutant. Monitoring and understanding the spatiotemporal evolution of ozone pollution is therefore a crucial societal issue. Observation of tropospheric ozone at continental and global scales is only possible by spaceborne remote sensing. However, standard spaceborne observations using single-band approaches using either UV or IR measurements show limited sensitivity to ozone in the atmospheric boundary layer, which is the major concern for air quality.
A new capacity to observe the daily distribution of ozone located at the lowermost troposphere (below 3 km of altitude) is now offered by an innovative multispectral synergism of IASI and GOME-2 measurements at the IR and UV respectively (Cuesta et al., 2013; 2018). This novel method called IASI+GOME2 retrieves ozone at the lowermost troposphere with a low mean bias, a linear correlation of 0.86 and a mean precision of 16% as compared to reference ozonesonde measurements around the world during all seasons. The retrieval sensitivity peaks down to 2 to 2.5 km over land during summer. This multispectral product is available at the IASI spatial resolution (pixels spaced by 25x25 km2) and for cloud fractions below 30%. IASI+GOME2 retrievals also show a good and currently unique agreement with respect to in situ measurements of ozone at the surface, over East Asia and Europe, for both ozone outbreak events and the seasonal evolution. IASI+GOME2 data is publicly available at the French data centre AERIS/ESPRI (http://cds-espri.ipsl.fr).
The current presentation focuses on the analysis of global observations of lowermost tropospheric ozone from IASI+GOME2. We study the main global hotspots of ozone at the lowermost troposphere at the tropics and mi-latitudes (e.g. over South and East Asia). We provide a new observational characterisation of the evolution and transport pathways of these ozone hotpots, in link with meteorological and dynamical conditions.
ESA Ozone Climate Change Initiative: combined use of satellite ozone profile measurements for trend analyses
Sofieva, Viktoria (1); Tamminen, Johanna (1); Kyrölä, Erkki (1); Weber, Mark (2); Rozanov, Alexei (2); Arosio, Carlo (2); Stiller, Gabriele (3); Laeng, Alexandra (3); von Clarmann, Thomas (3); Degenstein, Doug (4); Roth, Chris (4); Zawada, Daniel (4); Walker, Kaley A. (5); Sheese, Patrick (5); Hubert, Daan (6); Van Roozendael, Michel (6) - 1: Finnish Meteorological Institute, Finland; 2: Institute of Environmental Physics, University of Bremen, Germany; 3: Karlsruhe Institute of Technology, Germany; 4: University of Saskatchewan, Canada; 5: Department of Physics, University of Toronto, Canada; 6: BIRA-IASB, Belgium
The creation of homogenized long-term ozone datasets based on limb-viewing measurements from ENVISAT sensors (GOMOS, MIPAS, SCIAMACHY) as well as from ESA Third Party Missions (OSIRIS, SMR and ACE-FTS) is one of the objectives of the ESA ozone-CCI project.
In the framework of the ozone-CCI project, different datasets are created. The datasets from individual instruments are collected in the user-friendly HARMonized dataset of Ozone profiles (HARMOZ). For trend analyses, the ozone profile measurements from seven ESA and NASA satellite instruments (SAGE II, GOMOS, MIPAS, SCIAMACHY, ACE-FTS, OSIRIS, OMPS) are merged in a climate data record—the merged SAGE-CCI-OMPS dataset, which covers more than 30 years, from 1984 to 2017. This recently created dataset is used for evaluating ozone trends in the stratosphere through multiple linear regression. Negative ozone trends in the upper stratosphere are observed before 1997 and positive trends are found after 1997. The upper stratospheric trends are statistically significant at mid-latitudes and indicate ozone recovery, as expected from the decrease of stratospheric halogens that started in the middle of the 1990s and stratospheric cooling.
In the presentation, we will show the obtained results and discuss future developments.
The Production of 20+ Year Height-resolved Ozone Data from GOME-class Instruments for ESA-CCI and C3S
Latter, Barry Graham (1,2); Siddans, Richard (1,2); Kerridge, Brian (1,2) - 1: STFC RAL Space, Didcot, UK; 2: National Centre for Earth Observation (NCEO), UK
RAL's ozone profile retrieval scheme for the GOME-class of solar uv/vis backscatter spectrometer has unique sensitivity to tropospheric ozone, which led to its selection for nadir ozone profile retrieval from this class of sensor in ESA's Climate Change Initiative (CCI) and inclusion in the Tropospheric Ozone Assessment Report (TOAR). The JASMIN computing facility at RAL has enabled the production of full-mission global data sets from GOME-1, SCIAMACHY, OMI and GOME-2A & 2B, resulting in over 20 years of height-resolved dataset for ozone from 1995-2016, spanning both stratosphere and troposphere.
A reprocessing of data has been enabled under the Copernicus Climate Change (C3S) project and work is underway to reconcile these data time series. We present some of the retrieval scheme advancements and highlights of the latest version of the dataset, including comparisons with coupled chemistry climate models, chemical transport models and MACC/CAMS analyses.
The scheme has also been operating in near real-time for GOME-2 for several years. Following recent updates from CCI work, the data quality has improved. Highlights from the 2018 summer identified in the NRT scheme will also be presented.
Global total ozone trend assessment 1995-2017 using the extended ESA-CCI GTO-ECV data record
Coldewey-Egbers, Melanie (1); Loyola, Diego (1); Heue, Klaus-Peter (1); Dameris, Martin (1); Braesicke, Peter (2); Lerot, Christophe (3); Van Roozendael, Michel (3); Garane, Katerina (4); Koukouli, MariLiza (4); Balis, Dimitris (4) - 1: German Aerospace Center, Germany; 2: Karlsruhe Institute of Technology, Germany; 3: Royal Belgian Institute for Space Aeronomy, Belgium; 4: Aristotle University of Thessaloniki, Greece
We present an updated global total ozone trend assessment for the 22-year period from 1995 to 2017 using the European Space Agency's Climate Change Initiative (ESA-CCI) GOME-type Total Ozone Essential Climate Variable (GTO-ECV) data record. We show that the expected onset of ozone recovery - as a consequence of decreasing amounts of ozone depleting substances - is still largely masked by strong dynamically induced inter-annual variability. Only for small regions slight indications, i.e. significant positive trends, were found. Thus, uncertainty still remains as to the exact timing of ozone recovery, in particular in the middle latitudes. The GTO-ECV data record has been compiled from a series of nadir-viewing satellite instruments including GOME/ERS-2, SCIAMACHY/ENVISAT, GOME-2/MetOp-A, GOME-2/MetOp-B, as well as OMI/AURA. The individual sensors provide observations of the total ozone column with a high degree of consistency which has been achieved through the application of a common advanced direct retrieval algorithm GODFIT Version 4. Currently, GTO-ECV covers the past 22 years, but it is regularly extended on a quasi-operational basis as part of the EU Copernicus Climate Change Service operated by the European Centre for Medium-Range Weather Forecasts (ECMWF). Geophysical validation of the GTO-ECV data record using ground-based Dobson, Brewer and SAOZ (Système d’Analyse par Observation Zénitale) instruments has demonstrated its remarkable accuracy and long-term stability. In particular, GTO-ECV meets the specific requirements for total ozone formulated by the Global Climate Observing System (GCOS) program. In addition to the evaluation of spatially resolved inter-annual ozone variability and long-term trends, the data record is used to verify the abilities of Chemistry-Climate Models (CCMs) to reproduce the observed ozone features. Confronting model simulations with observations helps to identify the strengths and weaknesses of the model's system and to improve the description of the processes relevant for the short- and long-term ozone variability in a changing climate. We compare ozone trends derived from GTO-ECV with those obtained from different model simulations performed with the ECHAM/MESSY Atmospheric Chemistry (EMAC) CCM system. During the next two decades GTO-ECV will be further extended with measurements from the Copernicus mission Sentinel-5 Precursor (successfully launched in October 2107), the third GOME-2 instrument on-board MetOp-C (launch planned in September 2018), Sentinel-4, and Sentinel-5.
Ozone Profile Record from SBUV/OMPS Nadir Instruments: Present and Future Work
Kramarova, Natalya (1); Bhartia, P.K. (1); Frith, Stacey (2); Huang, Liang-Kang (2); Labow, Gordon (2); Ziemke, Jerald (3); McPeters, Richard (1); Seftor, Colin (2); DeLand, Mathew (2) - 1: NASA GSFC, United States of America; 2: Science Systems and Applications Inc., United States of America; 3: Morgan State University, United States of America
The global record of ozone profiles derived from nadir UV sensors – BUV, SBUV and SBUV/2 – is continued with the OMPS NP on board of Suomi NPP and JPSS-1 satellites. Ozone retrievals from multiple UV nadir instruments are combined into the merged ozone record for studying long-term ozone trends. Small offsets between the instruments can affect trend estimates and related uncertainties. In version 8.6, all SBUV instruments were accurately cross-calibrated, but nevertheless small but consistent differences in ozone between overlapping SBUV instruments were found. To understand and attribute these differences, we compared recent SBUV instruments with MLS observations and GEOS CCM model simulations. We found that some of the observed differences are related to geophysical effects. In the upper stratosphere, a large fraction of differences can be explained if the diurnal ozone cycle is accounted for. Using 13 years of MLS data, we developed an additive correction for the seasonal ozone climatology to account for the QBO vertical pattern in the low resolution nadir retrievals. Our ultimate goal is to improve cross-calibrations among SBUV sensors and therefore reduce uncertainties in the ozone trend.
14:05 - 15:35
Bromine monoxide/Sulphur dioxide molar ratios in volcanic plumes from S5-P/TROPOMI
Warnach, Simon (1,2); Sihler, Holger (1,2); Borger, Christian (1); Bobrowski, Nicole (1,2); Schöne, Moritz (2); Hörmann, Christoph (1); Beirle, Steffen (1); Platt, Ulrich (2); Wagner, Thomas (1) - 1: Max Planck Institut für Chemie, Mainz, Germany; 2: Institut für Umweltphysik, Uni Heidelberg, Germany
In this presentation, the potential of the recently launched TROPOspheric Monitoring Instrument (TROPOMI) I to detect bromine monoxide (BrO) in volcanic plumes is investigated. So far BrO in volcanic plumes has been successfully retrieved from satellite only during major eruptions. The high spatial resolution of S5P/TROPOMI (3.5x7km) and the daily global coverage allow for an investigation of volcanic BrO during small eruptions and even during continuous passive degassing. The continuous observation of passive degassing volcanoes yields the potential for long-term monitoring of volcanoes from satellite. Also, it is expected that the volcanic plumes can be tracked over larger distances.
BrO is a halogen radical altering – inter alia – the atmospheric ozone chemistry. BrO and in particular the molar BrO/SO2 ratios in volcanic gas emissions have been suggested as proxy for monitoring volcanic activity on several accounts.
In this study, we present BrO column densities as well as SO2 column densities retrieved using Differential Optical Absorption Spectroscopy (DOAS) and BrO/SO2 molar ratios in volcanic plumes with varying emission strength from TROPOMI data. By deriving a time series, we investigate the variation of the BrO/SO2 molar ratio of various volcanoes, in order to gain deeper insights into the plume chemistry and emission composition.
First year of Sulfur Dioxide Retrievals from Sentinel-5 Precursor TROPOMI instrument and comparison with independent satellites and ground-based datasets.
Theys, Nicolas (1); Hedelt, Pascal (2); De Smedt, Isabelle (1); Yu, Huan (1); Lerot, Christophe (1); Vlietinck, Jonas (1); Pedergnana, Mattia (2); Arellano, Santiago (3); Li, Can (4); Krotkov, Nickolay (4); Veefkind, Pepijn (5); Loyola, Diego (2); Van Roozendael, Michel (1) - 1: Royal Belgian Institute for Space Aeronomy, Belgium; 2: Deutsches Zentrum für Luft und Raumfahrt (DLR); 3: Chalmers University of Technology; 4: NASA Goddard Space Flight Center; 5: Royal Meteorological Institute of the Netherlands (KNMI)
The Sentinel-5 Precursor (S5P) platform was launched from Northern Russia on October 13, 2017 carrying the TROPOspheric Monitoring Instrument (TROPOMI). With a spatial resolution of 7x3.5 km², TROPOMI provides improved information on natural and anthropogenic emissions of trace gases and aerosols, with an unprecedented level of details.
BIRA-IASB and DLR have the joint responsibility of developing and maintaining the SO2 retrieval algorithm and its implementation into the S5P operational processor (Theys et al., 2017).
In this paper, we introduce the algorithm, present the first year of TROPOMI SO2 results for several degassing volcanoes and anthropogenic sources. Compared to the current OMI, OMPS and GOME-2 sensors, we observe a step change in satellite ability to monitor and quantify global SO2 point emissions sources. The improvements and new opportunities offered by TROPOMI are illustrated and discussed, and first validation results of the TROPOMI SO2 product with available concurrent satellite and ground-based measurements are presented. The retrieval challenges associated with higher resolution measurements are also addressed and plans for future work are outlined.
N. Theys, I. De Smedt, H. Yu, T. Danckaert, J. van Gent,C. Hörmann, T. Wagner, P. Hedelt, H. Bauer, F. Romahn, M. Pedergnana, D. Loyola, M. Van Roozendael : Sulfur dioxide operational retrievals from TROPOMI onboard Sentinel-5 Precursor: Algorithm Theoretical Basis, Atmos. Meas. Tech., 10, 119-153, doi:10.5194/amt-10-119-2017, 2017.
Anthropogenic Emissions and Satellite Inferred Tropospheric Formaldehyde Trends, Seasonality and Anomalies over South Asian Region
Ul Haq, Zia - University of the Punjab, Pakistan
This study is conducted to assess the spatiotemporal variability, trends and anomalies of Ozone Monitoring Instrument (OMI) derived tropospheric formaldehyde (tropo-HCHO) over South Asia land mass and some selected study zones during 2005-2015. This study also discusses anthropogenic emissions of HCHO estimated by MACCity (Monitoring Atmospheric Composition and Climate, MACC and megaCITY – Zoomfor the Environment, CityZEN. Anthropogenic emissions of HCHO have been observed to be averaged at 4.45×10-13 kg m-2 s-1 with an overall increment of 16.5%. The highest sectoral contribution is seen from transport sector averaged at 5.63×10-14 kg m-2 s-1. OMI data show tropo-HCHO averaged at 6.16±0.24×1015 molecules cm-2 with rise of 10.9%. The forest areas of study zone-5 consisting of eastern regions of India, Bangladesh and western regions of Myanmar, appear very prominent source of tropo-HCHO. The dependence of tropo-HCHO column on selected trace gases concentrations and meteorological factors has also been modeled showing reasonable correlation coefficients, up to r=0.94 over peninsular Indian region.
Extensive Validation of the OMI Formaldehyde Data Record (2005-2016) Using Ground-Based and Airborne Measurements and Model Simulations
Müller, Jean-François; Stavrakou, Trissevgeni; Bauwens, Maite; De Smedt, Isabelle - Royal Belgian Institute for Space Aeronomy (BIRA-IASB), Belgium
Spaceborne formaldehyde (HCHO) column data have been used in a number of inverse studies as top-down constraints on non-methane hydrocarbon emissions released into the atmosphere from the vegetation, fires and anthropogenic activities (Palmer et al. 2003, Stavrakou et al. 2009, Barkley et al. 2013, Zhu et al. 2014, Bauwens et al. 2016, Stavrakou et al. 2016). These estimations rely on the formation of HCHO at high yields in the photo-oxidation of the most atmospheric hydrocarbons. This work aims to validate the long-term dataset of formaldehyde (HCHO) column retrievals obtained from the OMI spectrometer in the framework of the EU QA4ECV project (De Smedt et al. 2018). This dataset constitutes a major improvement with respect to previous work thanks to the use of a larger fitting window (328.5-359 nm) allowing for noise reduction, and to a new background correction leading to improved column seasonality. The IMAGES CTM will be used as physical interpolator to assess the quality of the OMI columns. The consistency between OMI and a wide range of measurements will be assessed by using the models to bring together all measurement types (spaceborne, airborne, ground-based) into a unique framework.
The first validation dataset consists in long-term column data retrieved from ground-based FTIR and MAX-DOAS column measurements from 24 stations across the globe, representing different photochemical regimes, ranging from urban and rural regions to high altitude and pristine regions. The ground-based columns are compared to model columns accounting for the location, altitude, a priori profiles and averaging kernels, as well as for the temporal sampling of the measurements. The second validation dataset is an extensive compilation of data merges obtained from past airborne missions (INTEX-B, ARCTAS, DISCOVER-AQ, SENEX, SEAC4RS, KORUS-AQ) over North America, Korea, and the Pacific Ocean. Vertical profiles are built from daytime measurements, and the resulting partial columns are used to evaluate the model and the OMI data at the profile locations.
We find that the OMI retrieval shows a large degree of consistency with both validation datasets. The comparisons with aircraft data show a very good agreement for the majority of the missions, except over the Southeast US where the OMI data are found to be biased low by 25% and over the Western US where OMI is biased high by 35%. With respect to ground-based measurements, the OMI biases are within 35% at most sites, but the satellite retrieval is found to be strongly positively biased when compared to Arctic sites (e.g. Eureka, Thule). These discrepancies are further investigated and discussed.
High-Resolution Inversion of OMI Formaldehyde Data Over South America Using the Adjoint of the MAGRITTE Model
Stavrakou, Trissevgeni (1); Müller, Jean-François (1); Bauwens, Maite (1); De Smedt, Isabelle (1); Van Roozendael, Michel (1); Vigouroux, Corinne (1); Palm, Mathias (2) - 1: Royal Belgian Institute for Space Aeronomy (BIRA-IASB), Belgium; 2: Institute of Environmental Physics, University of Bremen, Bremen, Germany
South America is home to the largest rainforest in the world and its significant role on the global climate is widely recognized. This region alone holds about one third of the isoprene emission into the atmosphere, and is prone to intense fire events during the dry season, especially in years of major droughts like 2005 and 2010. Nevertheless, atmospheric composition and related processes in South America remain relatively unexplored, partly due to the inaccessibility of the Amazon forest resulting in the current scarcity of ground-based measurements, and to the South Atlantic anomaly in the Earth’s magnetic field reducing the number and quality of satellite observations.
This study is motivated by the currently incomplete knowledge of the emissions of volatile organic compounds and their monitoring over South America. It takes advantage of the latest formaldehyde (HCHO) column retrievals obtained from the OMI spectrometer in the framework of the EU QA4ECV project, and relies on the fact that the photo-oxidation of the large majority of hydrocarbons released in the atmosphere by vegetation and biomass burning lead to the formation of HCHO at high yields. Satellite observations of HCHO can therefore inform us on the magnitude and spatiotemporal variability of the biogenic and pyrogenic organic compounds.
Here we use the MAGRITTE regional chemistry-transport model and its adjoint to study the atmospheric composition and its seasonal and interannual evolution, by constraining the emissions of isoprene and biomass burning over 2005-2016 in a domain delimited as 15 N-35 S, 32-85 W. MAGRITTE runs at 0.5x0.5 degree horizontal resolution and uses boundary conditions from IMAGESv2 global model simulations (Bauwens et al. 2016, Stavrakou et al. 2018). The regional and global models share the same chemical mechanism, emissions and physical parameterizations. Anthropogenic VOC emissions and their speciation are obtained from EDGARv4.3.2 database (Huang et al. 2017), and from the HTAPv2.2 2010 inventory (Janssens-Maenhout et al. 2015) for the other species. Wildfires are taken from the GFED4 database (van der Werf et al. 2017) and biogenic emissions from the MEGAN-MOHYCAN model (Guenther et al. 2012, Bauwens et al. 2018). Monthly HCHO observations are used as top-down constraints and averaging kernels are taken into account in the calculation of model columns. Individual inversions are conducted for every year.
The optimized ‘top-down’ flux estimates will be analyzed to investigate (i) the seasonality and interannual variability of biogenic emissions over the Amazon basin, (ii) the intensity of biomass burning fluxes during fire events, in particular during major droughts, (iii) potential trends in the biogenic source. The inferred fluxes will be evaluated through model comparisons with ground-based remote sensing data, aircraft data (GABRIEL), and in situ surface concentration measurements.
Summer 2018 in Northern Latitudes: Formaldehyde Columns Observed with TROPOMI/S5P
De Smedt, Isabelle (1); Theys, Nicolas (1); Lerot, Christophe (1); Yu, Huan (1); Vlietinck, Jonas (1); Cheng, Zhibin (2); Pedergnana, Mattia (2); Loyola, Diego (2); Van Roozendael, Michel (1) - 1: bira-iasb, BelgiumRoyal Belgian Institute for Space Aeronomy (BIRA-IASB), Brussels, Belgium; 2: Institut für Methodik der Fernerkundung (IMF), Deutsches Zentrum für Luft und Raumfahrt (DLR), Oberpfaffenhofen, Germany
The Sentinel-5 Precursor (S5P) was successfully launched on the 13th of October 2017, with on board the TROPOspheric Monitoring Instrument (TROPOMI). With a spatial resolution about 15 times finer than OMI, TROPOMI has started to provide important information on natural and anthropogenic emissions of trace gases and aerosols, with an unprecedented level of details.
The prototype of the TROPOMI tropospheric formaldehyde (HCHO) retrieval algorithm has been developed at BIRA-IASB and implemented at the German Aerospace Center (DLR) in the S5P operational processor UPAS-2 (De Smedt et al., 2018).
In this work, we present the first year of HCHO observations with TROPOMI, with a special focus on the heat wave of summer 2018 over Northern latitudes. We first compare the TROPOMI HCHO observations with the 14-years QA4ECV OMI dataset (http://doi.org/10.18758/71021031) and assess their mutual consistency. Second, we address the impact of the heat weave that occurred in Northern latitudes last summer (and associated droughts, wildfires and extreme temperatures) on NMVOC emissions during that period. How do the biogenic emissions – traced by HCHO columns - compare to previous Northern latitude summers? What are the TROPOMI capabilities for watching wildfire plumes that occurred e.g. in California, Colorado, Siberia, or in Scandinavian and Iberian Peninsulas? What is the cause of enhanced HCHO levels over (semi)-enclosed water bodies?
De Smedt, I., Theys, N., Yu, H., Danckaert, T., Lerot, C., Compernolle, S., Van Roozendael, M., Richter, A., Hilboll, A., Peters, E., Pedergnana, M., Loyola, D., Beirle, S., Wagner, T., Eskes, H., van Geffen, J., Boersma, K. F., and Veefkind, P.: Algorithm theoretical baseline for formaldehyde retrievals from S5P TROPOMI and from the QA4ECV project, Atmos. Meas. Tech., 11, 2395-2426, https://doi.org/10.5194/amt-11-2395-2018, 2018
16:05 - 17:35
Sentinel-5 Precursor Data Product Validation Approach
Dehn, Angelika; Zehner, Claus; Saavedra de Miguel, Lidia - ESA/ESRIN, Italy
Sentinel-5 Precursor (S-5P) is the first of a series of atmospheric chemistry missions within the European Commission’s Copernicus Programme, launched successfully in October 2017. S-5P entered tits operational Phase at the end of April 2018 and provides continuity in the availability of global atmospheric data products between its predecessor missions SCIAMACHY (Envisat) and OMI (AURA) and the future Sentinel-4 and -5 series. S-5P delivers unique data regarding the sources and sinks of trace gases with a focus on the lower Troposphere including the planet boundary layer due to its enhanced spatial, temporal and spectral sampling capabilities as compared to its predecessors.
The S-5P satellite carries a single payload, namely TROPOMI (TROPOspheric Monitoring Instrument) that was jointly developed by The Netherlands and ESA. Covering spectral channels in the UV, visible, near- and short-wave infrared, it measures various key species including tropospheric/stratospheric ozone, NO2, SO2, CO, CH4, CH2O as well as cloud and aerosol parameters.
The geophysical validation and characterization of the TROPOMI Level 1 and Level 2 data products during the phase E2 is conducted by ESA at different levels. The so-called Mission Performance Center carries out the routine validation throughout the mission life-time and rely on the availability of independent data sets for example from ground based measurements or the so-called Fiducial Reference Measurement data sets, as well as the contributions from independent national Validation Teams coordinated by ESA under the Sentinel 5 Precursor Validation Team (S5PVT).
The overall ESA S5P Validation approach during the operational phase E2 will be presented in this paper.
TROPOMI in-flight calibration results
Kleipool, Quintus (1); Ludewig, Antje (1); Bartstra, Rolf (1,2); Leloux, Jonatan (1,3); Loots, Erwin (1); van der Plas, Emiel (1); Rozemeijer, Nico (1,3); Landzaat, Robin (1,3); Veefkind, Pepijn (1) - 1: Royal Netherlands Meteorological Institute KNMI, De Bilt, The Netherlands; 2: S&T Science and Technology B.V., Delft, The Netherlands; 3: TriOpSys B.V., Utrecht, The Netherlands
The Sentinel-5 Precursor (S5P) mission represents the first in a series of atmospheric observing systems within Copernicus. The S5P mission is a single-payload satellite in a low Earth orbit that provides daily global information on concentrations of trace gases and aerosols important for air quality, climate forcing, and the ozone layer.
The payload of the mission is the TROPOspheric Monitoring Instrument TROPOMI, which has been jointly developed by the The Netherlands and ESA, and consists of a spectrometer with spectral bands in the ultraviolet, the visible, the near-infrared and the shortwave infrared.
The S5P mission was launched on the 13th of October 2017 and has been injected into a near-polar, near sun-synchronous orbit by a ROCKOT launcher. The initial 6 months of in-orbit operation covered spacecraft, TROPOMI and ground segment level commissioning activities (Phase E1). Since the 30th of April 2018 the instrument is measuring in the nominal operations phase E2, due to last 6.5 years.
We report on the inflight calibration status of TROPOMI as derived during the first year in-flight and on updates to the L1b processor.
Sentinel-5p MPC Operational Data Validation Facility – System Description and First Results
Lambert, Jean-Christopher (1); Langerock, Bavo (1); Compernolle, Steven (1); Geunes, Yves (1); Granville, José (1); Hubert, Daan (1); Keppens, Arno (1); Rasson, Olivier (1); Verhoelst, Tijl (1); Niemeijer, Sander (2); Rino, Bruno (2); Dehn, Angelika (3); Eichmann, Kai-Uwe (4); Loyola, Diego (5); Saavedra de Miguel, Lidia (3); Sneep, Maarten (6); Stein-Zweers, Deborah (6); Veefkind, Pepijn (6); Wagner, Thomas (7); Zehner, Claus (3) - 1: Royal Belgian Institute for Space Aeronomy (BIRA-IASB), Belgium; 2: S[&]T, Delft, Netherlands; 3: ESA/ESRIN, Frascati, Italy; 4: IUP-UB, Bremen, Germany; 5: DLR, Oberpfaffenhoffen, Germany; 6: KNMI, De Bilt, Netherlands; 7: MPI-C, Mainz, Germany
Launched on October 13, 2017, ESA’s Sentinel-5 Precursor (Sentinel-5p) is the first atmospheric composition satellite of European Union's Copernicus Earth Observation programme. On board, the UV/VIS/NIR/SWIR spectrometers of TROPOspheric Monitoring Instrument (TROPOMI) measure on the global scale, on a daily basis, and at unprecedented horizontal resolution the atmospheric abundance of species related to air quality, climate forcing, ozone, UV radiation and volcanic hazards: O3, NO2, HCHO, SO2, CO, CH4, clouds, aerosols...
Developed with joint support from ESA and from The Netherlands, Germany, and Belgium, the Sentinel-5p Mission Performance Centre (MPC) operates the Validation Data Analysis Facility (VDAF), on which is based the routine TROPOMI validation service to ESA, Level-2 data developers, Copernicus services and other data users. Building upon a two-decade heritage of geophysical validation research with precursor instruments (GOME, SCIAMACHY, OMI, GOME-2) and on recent advances in QA practices and validation systems, VDAF has been tailored to the TROPOMI and Copernicus needs, with special emphasis on operational aspects. It ingests Fiducial Reference Measurements (FRM) archived at ESA’s Validation Data Centre (EVDC) and other validation data collected from ground-based monitoring networks (WMO's GO3OS, NDACC, SHADOZ, TCCON, TOLNET…), and it compares those data to TROPOMI data following community-endorsed protocols in an automated environment.
In this paper we report on the operational geophysical validation of TROPOMI data, with highlights on both the heritage and advances implemented in the MPC VDAF system, and with TROPOMI validation results illustrating the first months of operation to date.
Estimation of fields of natural atmospheric variability within Toward Unified Error Reporting (TUNER) project
Laeng, Alexandra (1); von Clarmann, Thomas (1); Errera, Quentin (2) - 1: KIT, Germany; 2: BIRA, Belgium
Uncertainty estimates of Earth observation data are considered adequate if they explain the differences found between the results of different measurement systems. While methodologies exist to intercompare datasets of different measurement geometry and vertical resolution, the natural variability along with less than perfect collocations of observations add another component to the differences, which is not explained by the error budgets. We develop a parametrizaton which will allow estimation of the variability-induced uncertainty as a function of the mean spatial and temporal distance of the measurements. To estimate the natural variability fields, high-resolved data from the BASCOE Model are used. The model run is driven by ERA interim analysis data, with an altitude resolution according to ERA interim. 28 gases and temperatures are included in the package. The statistics how the typical vmr-difference increases with spatial/time difference are calculated. This allow to build a regression function of the type Δvmr = f(Δl;Δt).
Romanian Ground-based and Airborne Approach in Support of ESA Cal/Val Activities
Nemuc, Anca (1); Nicolae, Doina (1); Dandocsi, Alexandru (1,2); Belegante, Livio (1); Ene, Dragos (1); Andrei, Simona (1); Marmureanu, Luminita (1); Marin, Cristina (1,2); Toanca, Florica (1); Carstea, Emil (1); Calcan, Andreea (3) - 1: National Institute of Research and Development for Optoelectronics, INOE; 2: University Politehnica of Bucharest; 3: National Institute for Aerospace Research Elie Carafoli, INCAS
Current facilities in Romania (South of Bucharest in Magurele) include active and passive remote sensing instruments (a multi-wavelength Raman depolarization lidar system, ceilometers, a sun-lunar CIMEL photometer, a double spectrometer PANDORA instrument, a FTIR, microwave radiometer) measuring various properties of aerosols, trace gases and clouds, but also an research aircraft(Swing and in situ cloud measurements), UAVs, and ground-based mobile platforms (trace gases concentrations). In situ instrumentation is dedicated also to aerosol chemical characterization(ACSM, SMPS, PM). Many of the instruments participated in the Quality Assurance programs of various continental networks such as EARLINET, AERONET, MWRNET, ACTRIS.
The Romanian Atmospheric Mobile Observation System-RAMOS is under implementation and will include new cutting-edge airborne and ground based instruments for trace gases monitoring. Due to these technological improvements RAMOS will be able to assess the required confidence of the different data products of various satellite missions (Sentinel-5P, ADM-Aeolus, EarthCARE).
Since 2011 Romanian team have been participated (datasets submitted) in several international campaigns such as CALIPSO-EARLINET CAL-VAL, EMEP winter (Jan.-Feb. 2013), ACTRIS ACSM (Jun. 2012 – May 2013), AROMAT-1 (Sep. 2014) AROMAT-2 (Aug-Sep. 2015 and May 2016), Finokalia PRE-TECT (April 2017). Through the synergy of measurements and algorithms we were able to identify mixture of aerosols including dust advections, long range transported and/or smoke from forest fires and strong anthropogenic contributions and few relevant study cases will be presented.
New state of art instruments (cloud and rain RADAR, scanning wind lidar, new multiwavelength multi-depolarization lidar, atmospheric radiation station) will be added and implemented on a new facility MARS- Magurele center for Atmosphere and Radiation Studies therefore the datasets will continuously expands offering the opportunity for validating satellites aerosol, cloud CCI, winds and radiation retrievals over Eastern Europe.
Demonstration of an Integrated Approach for the Validation and Exploitation of Atmospheric Missions
Nicolae, Doina (1); Binietoglou, Ioannis (1); Belegante, Livio (1); Ene, Dragos (1); Goloub, Philippe (2); Fuertes, David (2); Dubovic, Oleg (2); Torres, Benjamin (2); Lopatin, Anton (3); Cede, Alexander (4); Kreuter, Axel (4); Aspetsberge, Michael (5); Ogris, Georg (5) - 1: National Institute of R&D for Optoelectronics, Romania; 2: Laboratoire d’Optique Atmospherique, CNRS/University of Lille, Lille, France; 3: GRASP-SAS, Lille, France; 4: LuftBlick, Innsbruck, Austria; 5: Catalysts GmbH, Vienna, Austria
Efficient use of Earth Observation-EO data relies on multi source data access, interoperability, long-term data preservation, and definition standards. To address the societal benefits and scientific objectives set forth by the satellite atmospheric missions, the downstream services and GEOSS, coordinated development of synergistic ground-based measurements techniques and algorithms are needed.
Today, the technology and the know-how are concentrated in several observation networks (e.g. in Europe AERONET, EARLINET, PANDONIA, etc.), each with its own strategy regarding instruments and data handling procedures. Initiatives to join and harmonize such networks are now ongoing, e.g. ACTRIS (Aerosols, Clouds, and Trace gases Research InfraStructure) which was included in 2016 in the ESFRI roadmap and is currently in the preparatory phase. ACTRIS is covering ground-based in situ and remote sensing of the short-lived species in the atmosphere.
For the moment, access to ground-based data is granted through the different data centers independently, ACTRIS DC being one of the most complex and comprehensive. In most of the cases, the time delay between the collection of the data and the availability of the data products is of the order of months, as the data processing and submission relies on the individual stations. In the framework of several EU projects, ACTRIS has developed and improving GARRLiC (Generalized Aerosol Retrieval from Radiometer and Lidar Combined data). However, except AERONET, which developed a simple Data synergy tool to display in parallel sunphotometer products, HYSPLIT backtrajectories and MODIS/AQUA images, no synergetic approach has been coherently made up-to-now to link ground-based and satellite observations, and to provide composite data products. Validation of satellite products is therefore a difficult and time-consuming process, supported by research projects. Partially, this is due to the unavailability (in a suitable timeframe) of centralized independent data, but partially is because of the lack of appropriate validation tools, i.e. IT platforms allowing user-defined data mining, processing, re-gridding and visualization.
DIVA project (pilot) is about setting up a hub to collect, handle, archive, and exploit in a synergetic way observational data from ground and space, either for the validation of ESA and Copernicus missions, or for scientific purposes. The backbone of this synergy is GRASP (Generalized Retrieval of Aerosol and Surface Properties). The system is versatile and integrates ground-based (lidar, sun/lunar photometer and spectrometer), satellite and model data, stand-alone and synergetic algorithms for advanced data products, using combined data from different platforms and sensors, as well as innovative data mining and data visualization tools. A prototype software is developed to process combined data in a unified approach, and the software components are integrated in a backend processing infrastructure which may be further used as a platform for remote sensing data validation. The software is developed distributed, but integrated in one platform. Webservices and tools are implemented to integrate, run, monitor, distribute, and visualize the applications.
DIVA approaches the end of its phase 1, including preparation of inputs (lidar, photometer, spectrometer), development of the GRASP prototype, and setup of the processing environment.
17:35 - 19:00
High Altitude Pseudo Satellites – An Emerging Technology in Support of Atmospheric Sciences and Applications
Fehr, Thorsten (1); Davidson, Malcolm (1); Lizarraga Cubillos, Juan (1); Ciccolella, Antonio (2) - 1: ESA/ESTEC, Noordwijk, The Netherlands; 2: ESA/ESRIN, Frascati, Italy
Atmospheric satellite observations from missions such as Aeolus and Sentinel-5 Precursor are ideally suited to provide information on global and regional scales. However, due the spatial resolution of the instruments and the orbit characteristics of the satellite itself, they have only limited capability to provide long-term diurnal information on urban and local scale. This information, however, is essential for the understanding of important atmospheric processes, for example related to atmospheric composition or small-scale dynamics, as well as to enhance services, such as for urban air quality or GHG emission monitoring.
A new class of observation platforms, High-Altitude Pseudo-Satellites (HAPS), is currently emerging, bridging the gab between ground based, aircraft or balloon measurements and space-borne systems. HAPS are unmanned airborne platforms in the lower stratosphere at 20 km altitude or higher allowing station keeping above a fixed location or area for extended periods of up to several months. A number of industrial HAPS developments for both airplanes (heavier-than-air) and airships (lighter-than-air) are on-going and first promising results have been achieved, such as the 25 days flight of the Airbus Zephyr HAPS system in summer 2018, the longest duration flight ever. HAPS payload capacities are diverse depending on the technology chosen and range from 5 kg to 250 kg. Miniaturized Earth observation instruments, e.g., for microsatellites, have been proposed and partially demonstrated for various applications comply with the weight and power requirements of HAPS.
In the frame of ESA’s HAPS4ESA symposium in October 2017 and other consultations, the atmospheric science and application domain has shown great interest in exploiting this emerging technology. In addition to the potential long-term atmospheric observation of a specific target area, HAPS are ideally suited to support the development of new space-borne instruments by flying technology demonstrations in conditions similar to space and for targeted calibration and validation activities of new and established satellite missions. A wide range of atmospheric remote sensing instruments has been proposed for HAPS with some already existing. In addition, the science community was already active in proposing specific case studies, ranging from meteorological applications to Air Quality and GHG activities. In response, ESA has issued an open call for project proposals that aim to identify HAPS mission concepts in support of Air Quality and GHG monitoring complementing the space-borne and ground based observation capabilities in Spring 2018.
The paper will provide an overview on HAPS technologies, their relation to ESA’s atmospheric satellite mission and how HAPS can generally support the atmospheric science community as a whole.
Development of the Sentinel-4 Products for Air Quality and Climate Monitoring
Loyola, Diego (1); Aspetsberger, Michael (2); Dubovik, Oleg (3); Fantin, Daniele (4); Govaerts, Yves (5); Richter, Andreas (6); Van Roozendael, Michel (7); Siddans, Richard (8); Veefkind, Pepijn (9); Wagner, Thomas (10); Wright, Norrie (11); Alvarado, Leonardo (6); Argyrouli, Athina (1); Beirle, Steffen (10); Bovensmann, Heinrich (6); Cobarzan, Corvin-Petrut (2); Efremenko, Dmitry (1); Eskes, Henk (9); van Gent, Jeroen (7); De Graaf, Martin (9); Hedelt, Pascal (1); Heue, Klaus-Peter (1); Latter, Barry (8); Lelli, Luca (6); Lerot, Christophe (7); Lopatin, Anton (3); Luffarelli, Marta (5); Lutz, Ronny (1); Lytvynov, Pavel (3); Pedergnana, Mattia (1); Pukite, Janis (10); Le Rille, Olivier (11); Romahn, Fabian (1); Sanders, Bram (6); Skahjem-Eriksen, Robin (4); Slijkhuis, Sander (1); De Smedt, Isabelle (7); Smith, Andy (8); Nanda, Swadhin (9); Theys, Nicolas (7); Valks, Pieter (1); Veihelmann, Ben (11); Warnach, Simon (10); Xu, Jian (1); Yu, Huan (7); Zimmer, Walter (1) - 1: German Aerospace Center (DLR), Germany; 2: Catalysts, Austria; 3: Laboratoire d'Optique Atmosphérique (LOA), France; 4: S[&]T, Norway; 5: Rayference, Belgium; 6: Institute of Environmental Physics (IUP Bremen), Germany; 7: Institute for Space Aeronomy (BIRA-IASB), Belgium; 8: STFC, Rutherford Appleton Laboratory (RAL), U.K; 9: Royal Netherlands Meteorological Institute (KNMI), The Netherlands; 10: Max Planck Institute for Chemistry (MPIC), Germany; 11: ESA/ESTEC, The Netherlands
The Sentinel-4 (S4) mission focuses on monitoring of trace gas column densities and aerosols over Europe at high spatial resolution with an hourly revisit time, thereby covering the diurnal variation of atmospheric constituents.
In this article we present the Level 2 (L2) products being developed in the framework of the ESA S4-L2 project: O3 total and tropospheric column, NO2 total and tropospheric column, SO2, HCHO, CHOCHO columns, aerosol and cloud properties as well as surface reflectance.
The S4-L2 work comprises the development of bread-boarding algorithms, independent verification algorithms, prototype processors and ultimately the operational S4-L2 processors for the generation of state-of-science operational data products.
A Nadir-Limb Matched Nitrogen Dioxide Data Product Derived from OSIRIS and OMI Measurements
Degenstein, Doug (1); Bourassa, Adam (1); Adams, Cristen (2); McLinden, Chris (3) - 1: University of Saskatchewan, Canada; 2: Alberta Environmental Monitoring and Science Division; 3: Environment and Climate Change Canada
The OSIRIS instrument has measured vertical profiles of nitrogen dioxide number density within the stratosphere since its launch in early 2001. The OSIRIS measurements of limb scattered sunlight have been demonstrated to produce high quality vertical nitrogen dioxide profiles that have been used in many studies of stratospheric chemistry. Recently, there has been significant activity associated with limb-nadir matching and progress has been made in the development of techniques that involve using results inferred from both limb scattered sunlight and surface reflected sunlight to improve the accuracy of tropospheric nitrogen dioxide column density measurements. This paper will present results from a new data record of the column density of nitrogen dioxide derived from OMI and OSIRIS measurements. It will also present preliminary results from additional studies that are designed to show the improvements to air quality forecasts that are expected from this improved tropospheric nitrogen dioxide product.
Rest Days Detected From Space: on the Weekly Cycle of NO2 Columns Over World’s Largest Cities
Bauwens, Maite (1); Stavrakou, Trissevgeni (1); Müller, Jean-François (1); Boersma, Folkert (2); van Geffen, Jos (2) - 1: Royal Belgian Institute for Space Aeronomy (BIRA-IASB), Brussels, Belgium; 2: Royal Netherlands Meteorological Institute, KNMI, De Bilt, The Netherlands
About 60% of the total NOx emission into the atmosphere is estimated to be due to fossil fuel combustion and other anthropogenic activities. Rest days induce therefore a weekly cycle in NO2 concentrations, with low week-end values observed both by ground-based measurements, and by spaceborne NO2 data (Beirle et al. 2003).
Here we use tropospheric NO2 column observations from the OMI sensor over 2005-2017 provided by the recently released QA4ECV product (Boersma et al. 2017). This retrieval incorporates recent advances in differential optical absorption spectroscopy, and leads to smaller slant column uncertainties than previous retrievals, although systematic fitting errors are not completely removed (Zara et al 2018). Tropospheric NO2 columns are calculated by using data assimilation and TM5-MP model profiles at 1ox1o so that hotspot gradients are better resolved. The OMI columns are averaged for each day of the week and each year between 2005 and 2017 for every city of more than 700,000 inhabitants according to the GeoNames database, using data lying within a 40 km radius of the city. The calculation is performed per season, for summer (June, July and August) and winter (December, January and February) months. Scenes with cloud fraction higher that 20% and surface albedo higher than 30% are excluded from the analysis.
Evidence of a rest day in the weekly cycle, i.e. a day with significantly lower NO2 column, is found in 131 cities in summertime, of which 22 are in the US, 21 in Europe, 16 in Japan, 11 in South Korea, and 10 in the Middle East. In line with previous studies which considered a more limited number of cities, we find a marked Sunday minimum in many (North and South) American, European, Australian and Japanese cities, with NO2 columns being between 10% and 50% lower on Sunday compared to weekdays. The analysis indicates a Friday minimum of the NO2 columns by 10-20% in Muslim cities in the Middle East and a Saturday minimum of 20% in Jerusalem. In Africa, Russia, India and China, no significant weekly cycle is observed. Similar results are found in winter, but the number of cities exhibiting a significant minimum is much lower (69). Based on these observations, we will further evaluate the weekly cycle variation assumed in models by performing sensitivity simulations with the MAGRITTE model over North America and different hypotheses for the weekly cycle of anthropogenic NOx emissions.
Estimating Stratospheric NO2 from Nadir-viewing Satellites: New Challenges for Sentinel-4 (and other upcoming Geostationary Missions)
Beirle, Steffen; Pukite, Janis; Wagner, Thomas - Max-Planck-Institut für Chemie, Germany
The STRatospheric Estimation Algorithm from Mainz (STREAM) determines stratospheric columns of NO2 which are needed for the retrieval of tropospheric columns from satellite observations. STREAM does not require input from chemical transport models, but is based on the total column measurements over clean, remote regions as well as over clouded scenes where the tropospheric column is effectively shielded. It was developed as verification algorithm for TROPOMI, as complement to the operational stratospheric correction based on data assimilation. STREAM was successfully applied to the UV/vis satellite instruments GOME 1/2, SCIAMACHY, and OMI. It overcomes some of the artefacts of previous algorithms, as it is capable of reproducing gradients of stratospheric NO2, e.g. related to the polar vortex, and reduces interpolation errors over continents.
Upcoming geostationary measurements do not cover remote oceans, which so far were a significant contributor to the stratospheric estimate. Instead, the stratospheric estimate has to rely on measurements in remote continental regions as well as over cloudy scenes. As geostationary satellites will provide multiple measurements per day, the number of suitable clouded measurements will be far higher than for the instruments used so far on low orbit.
Here we investigate how far STREAM can be applied to the upcoming geostationary Sentinel-4 mission, and which modifications of the algorithm are necessary. The analysis is based on synthetic NO2 slant column densities, which have been calculated within the Sentinel-4 verification project, using the chemical transport models TM5 and Lotos-Euros and the radiative transfer model SCIATRAN.
Validation of TROPOMI tropospheric NO2 using 3-D MAX-DOAS measurements in the Brussels area.
Dimitropoulou, Ermioni; Van Roozendael, Michel; Hendrick, Francois; Merlaud, Alexis; Pinardi, Gaia; Tack, Frederik; Fayt, Caroline; Hermans, Christian - Royal Institute for Space Aeronomy, Belgium
Tropospheric NO2 is an anthropogenic pollutant characterized by a variety of important roles in atmospheric chemistry. It is mainly emitted by combustion processes associated to traffic, industrial activity and domestic heating. NO2 is generally seen as a proxy of air pollution, as it is one of the most significant precursors of photochemical ozone production (O3) and nitric acid (HNO3). For this reason, its continuous monitoring is of major importance. One technique, which has been widely used, is the Multi-Axis Differential Optical Absorption Spectroscopy (MAX-DOAS) technique in order to extract simultaneous measurements of atmospheric trace gases and their vertical distribution in the troposphere. Using this technique, many species can be measured and one among them is the nitrogen dioxide.
In the present study, MAX-DOAS measurements from the BIRA-IASB research grade spectrometer operated in Uccle (Brussels, Belgium) are used to develop and demonstrate new approaches for investigating the vertical and horizontal spatial distributions of NO2 under moderate to high pollution conditions, such as encountered in Brussels and its suburban area. More precisely, the BIRA-IASB MAX-DOAS was set to operate two different modes: a vertical scan composed by 11 elevation angles in a fixed azimuth angle and an azimuthal scan (15 azimuth angles) at a constant elevation angle. The new measurement schedule allows us the retrieval of 3-D NO2 distributions.
A four-step retrieval has been used at two different wavelengths (based on Sinreich et al., 2013; Ortega et al., 2015) in order to describe the spatial and temporal concentration gradients of NO2 and to identify the most important emission source areas in and around Brussels. This will be complemented by car-DOAS measurements with the BIRA AEROMOBIL, and in-situ observations from the air quality telemetric network of Brussels that will be jointly exploited to study the horizontal and vertical distribution of tropospheric NO2. Finally, the retrieved NO2 is being compared with the TROPOMI satellite observations in order to support the validation of the satellite.
Satellite-based analysis of surface-level Ozone - NOx-VOC sensitivity
Sundström, Anu-Maija; Kujanpää, Jukka; Kalakoski, Niilo; Ialongo, Iolanda; Tamminen, Johanna - Finnish Meteorological Institute, Finland
Surface-level ozone (O3) is secondary air pollutant that is formed via UV-radiation driven chemical reactions from precursor gases such as nitrogen oxides (NOx) and volatile organic compounds (VOCs). High concentrations of surface-level O3 impact detrimentally human health, agriculture, and ecosystems. Recently published Tropospheric Ozone Assessment Report (Schultz et al., 2017) revealed that e.g. in many parts of southern Europe, US and Asia unhealthy levels of ground-level ozone is observed regularly.
In continental regions the formation of surface O3 concentration depends highly on the availability of the two precursor gases, NOx and VOCs. The production of O3 can be either NOx or VOC limited. In the NOx-limited (or VOC -saturated) regime the O3 formation is almost entirely controlled by NOx concentrations. In this regime the reduction of NOx emissions reduce the photolysis of NO2 and thus the formation of O3. On the other hand, in the VOC-limited (or NOx- saturated) regime reduced VOC emissions lead in turn to lower concentrations of ambient O3.
To effectively mitigate the surface level O3 pollution requires knowledge on which precursor, or both, is/are contributing most to the surface O3 formation. The O3-NOx-VOC sensitivity can be analyzed by defining a VOC- to- NOx ratio, which indicates whether the O3 formation process is NOx-or VOC-limited. From satellite observations the ratio can be obtained by using formaldehyde (HCHO) as a proxy for VOCs, and tropospheric NO2 columns to characterize NOx (e.g. Jin et al. (2017) and Jin and Holloway (2015)). In this work we will study the spatial and temporal variations in O3 sensitivity by using HCHO and NO2 data from GOME-2 and OMI satellite instruments. We will also analyze the variations in the O3 production rate in NOx-limited regions by using the GOME-2 NO2 photolysis product developed at the Finnish Meteorological Institute (Kujanpää and Kalakoski, 2015). Potential improvements of using high-resolution TROPOMI observations in this kind of application will be also discussed.
Jin, X., and T. Holloway (2015): Spatial and temporal variability of ozone sensitivity over China observed from the Ozone Monitoring Instrument, J. Geophys. Res. Atmos., 120, 7229–7246.
Jin,X. et al. (2017): Evaluating a space-based indicator of surface ozone-NOx-VOC sensitivity over midlatitude source regions and application to decadal trends. Journal of Geophysical Research: Atmospheres, 122, 10,439–10,461.
Kujanpää and Kalakoski (2015): Operational surface UV radiation product from GOME-2 and AVHRR/3 data, Atmos. Meas. Tech, 8, 4399–4414.
Schultz, M.G. et al. (2017): Tropospheric Ozone Assessment Report: Database and Metrics Data of Global Surface Ozone Observations, Elementa Sci. Anthrop, 244.
Using Sentinel-5P Data to Improve Air Quality Maps
Doubalova, Jana; Horalek, Jan; Juras, Roman; Vlcek, Ondrej - Czech Hydrometeorological Institute, Czech Republic
Air quality mapping plays an important role in informing the public about air pollution levels as well as in the assesment of air quality in areas not covered by measuring stations. For this purpose various data sources can be utilized, in particular in-situ measurements, air quality models and satellite data. Within the scope of the ESA funded project SAMIRA (SAtellite based Monitoring Initiative for Regional Air quality) we have been testing data fusion techiques that combine these data sources to provide more accurate information within air quality mapping.
Here we present results obtained with the newly available Sentinel-5P/TROPOMI satellite data. We have applied the developed data fusion techniques (multiple linear regression followed by interpolation of residuals) to create NO2 air quality maps over the region of the Czech Republic. Apart from the Sentinel-5P/TROPOMI data, we have used in-situ measurements from the air quality database of the Czech Hydrometeorological Institute and the chemical transport model CAMx.
The preliminary results show that the Sentinel-5P/TROPOMI can improve the bias of the maps as compared to mapping done using in-situ and model data only. We will also evaluate the results against maps created with OMI data to assess the the different impacts of the two instruments.
Shipping Signals in S5P NO2 data
Richter, Andreas; Sanders, Abram; Lange, Kezia; Burrows, John P. - University of Bremen, Germany
Ships emit large quantities of nitrogen oxides (NOx) into the marine boundary layer, and with ship bound international transport volume strongly increasing over the last two decades, the relevance of these emissions has as well. The signature of ship emissions has been picked up in tropospheric NO2 maps derived from measurements of the GOME, SCIAMACHY, GOME2, and OMI instruments. However, detection of shipping NOx in these data sets is mostly limited to the main shipping routes and to averages over months and even years. The TROPOMI instrument, recently launched on the Sentinel-5 precursor satellite, has the potential to improve on this situation owing to its better spatial resolution and excellent signal to noise ratio. In this study, a first qualitative assessment is given of the shipping signals detected in the first months of S5p data, using both the operational and the University of Bremen S5p NO2 data.
Detection of Anthropogenic CO2 Emission Areas from Space
Hakkarainen, Janne; Ialongo, Iolanda - Finnish Meteorological Institute, Finland
Anthropogenic CO2 emissions from fossil fuel combustion have large impacts on climate. In order to monitor the increasing CO2 concentrations in the atmosphere, accurate spaceborne observations—as available from the Orbiting Carbon Observatory-2 (OCO-2)—are needed. In our recent work [Hakkarainen et al., 2016] we provided a new approach to study anthropogenic CO2 emission areas by deseasonalizing and detrending OCO-2 XCO2 observations for deriving XCO2 anomalies. The spatial distribution of the XCO2 anomaly matches the features observed in the maps of the Ozone Monitoring Instrument NO2 tropospheric columns, used as an indicator of atmospheric pollution, as well as the features observed in the ODIAC emission dataset. In addition, the results of a cluster analysis confirmed the correlation between CO2 and NO2 spatial patterns.
In this work, we study this idea further and provide the global XCO2 anomalies for three full years 2015, 2016 and 2017. The patterns observed in these maps are compared with inventory-based estimates given by the Lagrangian particle dispersion model FLEXPART driven by the high-resolution ODIAC emission dataset. We also use data from the TROPOspheric Monitoring Instrument (TROPOMI), launched on October 13th, 2017 on board of the Copernicus Sentinel-5 Precursor satellite. TROPOMI provides daily global coverage with a spatial resolution of 7 km × 7 km in nadir direction, and observes NO2, SO2 and CO, among other atmospheric parameters. We analyze these data in synergy to better detect anthropogenic CO2 sources and plumes.
Hakkarainen, J., I. Ialongo, and J. Tamminen (2016), Direct space-based observations of anthropogenic CO2 emission areas from OCO-2, Geophys. Res. Lett., 43, 11,400–11,406, doi:10.1002/2016GL070885.
Carbon Monoxide Total Column Retrievals from Sentinel-5P Short-Wave Infrared Nadir Measurements
Hochstaffl, Philipp Ludwig; Schreier, Franz - German Aerospace Center (DLR), Germany
We present our first results in the Level1-2 processing of carbon monoxide (CO) total columns from Sentinel-5P (S5P) Short-Wave Infrared (SWIR) observations. The retrievals will be performed using the Beer Infrared Retrieval (BIRRA). BIRRA performs a least squares fit of Earth’s radiance (essentially transmission) to retrieve the molecular column densities (essentially density scaling factors) along with some auxiliary parameters (reflectivity etc.) [Gimeno Garcia et al., AMT 2011]. It has been developed at DLR since about 2005 and its computational core modules have been integrated in the operational SCIAMACHY (Scanning Imaging Absorption Spectrometer for Atmospheric Chartography) L1b-2 processor to retrieve CO from channel 8 (2.3 microns) and methane from channel 6 (1.6 microns) nadir observations. In the framework of DLR's SCIAMACHY activities BIRRA CO columns have been thoroughly examined in several intercomparisons [e.g. Hochstaffl et al., Remote Sens.\ 2018]. The forward model of BIRRA is essentially based on the GARLIC (Generic Atmospheric Radiation Line-by-line Infrared Code, Schreier et al. 2014) which has also been thoroughly verified and validated in numerous studies [Schreier et al., JQSRT 2018; Schreier et al., Molec. Astrophysics 2018].
In this study we will use the latest version of the BIRRA prototype featuring new enhancements such as advanced line shapes accounting for line mixing and speed dependence. An updated framework is providing appropriate auxiliary information (e.g. latest molecular spectroscopy data, a priori atmospheric profiles of pressure, temperature, and concentrations of interfering species, topography, ...).
Finally, for diagnostic analysis we will consider the residual norms, residual spectra, the distribution of errors of the state vector elements, and comparisons with other data products. More specifically, we intend to estimate the quality of the product in view of the accuracy requirements defined in the mission preparation phase (i.e. 15% for CO) using NDACC (Network for the Detection of Atmospheric Composition Change) or TCCON (Total Carbon Column Observing Network) ground-based observations.
Intercomparison of Different Gas Analyzers that Measure CO, CH4 and NO2 Concentration in Atmosphere
Grigoras, Georgiana (1); Calcan, Andreea (1); Ardelean, Magdalena (1); Radu, Cristian (2) - 1: National Institute for Aerospace Research "Elie Carafoli" - INCAS, Romania, Bvd. Iuliu Maniu no. 220, 6th District, 061126, Bucharest, Romania; 2: National Institute for Research and Development in Optoelectronics INOE 2000, Atomiștilor Street no. 409, 77125, Măgurele, Romania
Observation of the chemical composition of the atmosphere is an important study area of atmospheric research that has led to the development of various instruments that provide as precise information as possible about the concentration of pollutants in the atmosphere. In this paper, an intercomparison of different instruments for measurement of CO, CH4 and NO2 concentration was carried out. Continuous measurements of these pollutants were recorded during in situ campaign in Magurele town, in July 2017. The CO and CH4 concentrations measurements were accomplished using an analyzer based on the cavity ring-down spectroscopy (CRDS) technique and were compared to those measured by the ambient carbon monoxide (CO) monitor using the non-dispersive infrared analysis method as its operating principle, respectively, the ambient hydrocarbon (HC) monitor based on the selective combustion method and hydrogen flame ionization method. For the NO2 concentrations, the measurements from Optical absorption CAPS (Cavity attenuated phase-shift spectroscopy technique) NO2 analyzer and an ambient nitrogen oxide monitor using the chemiluminescence (CLD) method as its operating principle were inter-compared. The results obtained using these techniques are comparable, strong correlation coefficient were obtained.
Copernicus Climate Change Service (C3S) Satellite-derived Carbon Dioxide and Methane Data Products
Buchwitz, Michael (1); Reuter, Maximilian (1); Schneising, Oliver (1); Bovensmann, Heinrich (1); Burrows, John P. (1); Boesch, Hartmut (2); Anand, Jasdeep (2); Parker, Robert (2); Detmers, Rob G. (3); Aben, Ilse (3); Hasekamp, Otto P. (3); Crevoisier, Cyril (4); Armante, Raymond (4); Schepers, Dinand (5) - 1: University of Bremen, Bremen, Germany; 2: Earth Observation Science, University of Leicester, and NERC National Centre for Earth Observation, Leicester, United Kingdom; 3: SRON Netherlands Institute for Space Research, Utrecht, Netherlands; 4: Centre National de la Recherche Scientifique (CNRS), Laboratoire de Météorologie Dynamique (LMD), Palaiseau, France; 5: European Centre for Medium-Range Weather Forecasts (ECMWF), Reading, United Kingdom
Carbon dioxide (CO2) and methane (CH4) are important atmospheric greenhouse gases (GHG) and, therefore, classified as Essential Climate Variables (ECVs). Previously, satellite-derived atmospheric CO2 and CH4 ECV data sets have been generated and made available via the GHG-CCI project of the European Space Agency’s (ESA) Climate Change Initiative (CCI, http://www.esa-ghg-cci.org/). The latest GHG-CCI data set, Climate Research Data Package No. 4 (CRDP 4), covers the time period 2003-2015 and was made available in February 2017. Currently, the production and provision of these data sets is being continued operationally via the Copernicus Climate Change Service (C3S, https://climate.copernicus.eu/), which is implemented by the European Centre for Medium-Range Weather Forecasts (ECMWF) on behalf of the European Commission. The C3S satellite greenhouse gas (GHG) sub-project (C3S_312a_Lot6) is led by University of Bremen supported by University of Leicester (UK), SRON (The Netherlands) and CNRS-LMD (France). The first Climate Data Record (CDR) data set produced and delivered within the C3S framework covers the period 2003-2016 and consists of column-average dry-air mole fraction CO2 and CH4 products, i.e., XCO2 and XCH4, from SCIAMACHY/ENVISAT and TANSO-FTS/GOSAT. In addition, mid-tropospheric CO2 and CH4 mixing ratios from IASI Metop-A and Metop-B are part of this data set and mid-tropospheric CO2 from AIRS. These data products have been made publicly available in mid 2018 via the C3S Climate Data Store (CDS, https://cds.climate.copernicus.eu/) and the data products are regularly updated. This new Earth Observation data set will reviewed in the presentation.
ARRHENIUS: a Geostationary Carbon Process Explorer for Africa, Europe and the Middle-East
Butz, Andre (1); Palmer, Paul (2); Bösch, Hartmut (3); Bousquet, Philippe (4); Bovensmann, Heinrich (5); Brunner, Dominik (6); Bugliaro, Luca (7); Crisp, David (8); Crowell, Sean (9); Cuesta, Juan (10); Gloor, Emanuel (11); Houweling, Sander (12); Landgraf, Jochen (13); Marshall, Julia (14); Dils, Bart (15); Miller, Charles (8); Nassar, Ray (16); Orphal, Johannes (17); van der Werf, Guido (12) - 1: Insitute of Environmental Physics, University of Heidelberg, Germany; 2: School of GeoSciences, University of Edinburgh, United Kingdom; 3: Earth Observation Center, University of Leicester, United Kingdom; 4: Université de Versailles Saint-Quentin en Yvelines, Laboratoire des sciences du climat et de l’environnement (LSCE), Gif sur Yvette, France; 5: Institute for Environmental Physics, University of Bremen, Germany; 6: Eidgenössische Materialprüfungs- und Forschungsanstalt (EMPA), Dübendorf, Switzerland; 7: Deutsches Zentrum für Luft- und Raumfahrt e.V., Oberpfaffenhofen, Germany; 8: Jet Propulsion Laboratory, Pasadena, USA; 9: University of Oklahoma, USA; 10: Laboratoire Inter-Universitaire des Systèmes Atmosphériques (LISA), Université Paris Est Créteil (UPEC), France; 11: School of Geography, University of Leeds, United Kingdom; 12: Vrije Universiteit of Amsterdam, Department of Earth Sciences, The Netherlands; 13: Netherlands Institute for Space Research (SRON), Utrecht, The Netherlands; 14: Max Planck Institute for Biogeochemistry, Jena, Germany; 15: Royal Belgian Institute for Space Aeronomy (BIRA-IASB), Brussels, Belgium; 16: Environment and Climate Change Canada, Toronto, Canada; 17: Institute of Meteorology and Climate Research (IMK), Karlsruhe Institute of Technology (KIT), Germany
Tropical and subtropical ecosystems play an important role in the global carbon cycle. The African tropics and subtropics is the most dynamic region of the world with respect to terrestrial carbon flux variability and population growth, which imposes direct carbon emissions and perturbations to the natural ecosystems. The underlying mechanisms such as photosynthesis, respiration, natural and man-made biomass burning, as well as fossil fuel related emissions vary on sub-daily timescales. The forcing by meteorological and climatic factors imposes a fingerprint being variable on the seasonal and inter-annual time-scale. Event-wise emissions such as caused by agricultural burning blend with episodic change in land-use practices and permanent ecosystem degradation. Thus, gaining insights into the functioning of African tropical and subtropical carbon cycling and into its sensitivity to environmental variability and perturbations needs observations from the sub-daily to the seasonal to the year-to-year time-scale. However, the African continent is poorly sampled by current and planned atmospheric observation systems. Establishing a dense and robust ground-based network is logistically challenging. Satellite observations from low-Earth-orbit (LEO) are limited to a single local overpass time per day and, they are frequently cloudy.
The Middle East and Europe are major global players in fossil fuel extraction and usage, respectively. Leakage of carbon gases has been reported throughout the extracting-processing-transportation-consumption chain. Satellite observations from LEO will become progressively available as part of envisioned surveillance concepts. These LEO sensors, however, do not capture characteristic diurnal variations of fluxes, potentially resulting in biased emission estimates and lacking the ability to discriminate between man-made and biospheric flux signals.
The AbsoRption spectRometric patHfindEr for carboN regIonal flUx dynamicS (ARRHENIUS) is a proposed mission concept that will overcome the sampling gaps in the tropics and subtropics and on the sub-daily time scale by adopting a process-focused sampling strategy from geostationary orbit (GEO). For selectable focus regions, ARRHENIUS will deliver quasi-contiguous maps of atmospheric carbon species concentrations (carbon dioxide (CO2), methane (CH4), and carbon monoxide (CO)) and a photosynthesis process marker (solar induced plant fluorescence (SIF)) with sub-daily, seasonal, and year-to-year coverage. These observations will be used by top-down inverse atmospheric models and by bottom-up biosphere and land-surface models to inform on regional carbon cycle processes. Being process focused instead of surveillance driven, ARRHENIUS will pioneer a flexible and intelligent sampling approach with short lead times for pointing adjustments. Sampling will be flexible with regard to focus region selection, region extent (typically 1300x2400 km2), dwell times (typically 1h) and the number of revisits per day (up to 5 times per day), per season and per year. Sampling will be intelligent by actively avoiding regions which are expected cloudy based on observations of meteorological sounders (such as Meteosat Third Generation) from adjacent orbits. Small footprint sizes (2x2 km2 at sub-satellite) and flexible day-time observation hours will further support cloud avoidance.
Application of WFM-DOAS Retrieval Algorithm to TROPOMI Radiances: First Carbon Monoxide and Methane Retrieval Results
Schneising, Oliver; Buchwitz, Michael; Reuter, Maximilian; Bovensmann, Heinrich; Burrows, John P. - University of Bremen, Germany
Carbon monoxide (CO) is an important atmospheric constituent affecting air quality and methane (CH4) is the second most important greenhouse gas contributing to human-induced climate change. Detailed and continuous observations of these gases are necessary to better assess their impact on climate and atmospheric pollution.
The TROPOspheric Monitoring Instrument (TROPOMI) on board the Sentinel-5P, which was successfully launched in October 2017, is a spaceborne nadir viewing imaging spectrometer covering wavelength bands between the ultraviolet (UV) and the shortwave infrared (SWIR). It combines daily global coverage with a high spatial resolution of 7×7 km2 .
Abundances of atmospheric CO and CH4 can be retrieved from TROPOMI’s radiance measurements in the 2.3 μm spectral range of the shortwave infrared part of the solar spectrum. Here we present first results for both trace gases obtained using the scientific retrieval algorithm WFM-DOAS.
Nonlinearity of the OCO-2 XCO2 retrieval – an application of Dimension Deduction MCMC for OCO-2 Surrogate Forward Model XCO2 retrieval
Lamminpää, Otto (1); Brynjarsdottir, Jenny (2); Hobbs, Jonathan (3); Braverman, Amy (3); Laine, Marko (1); Tamminen, Johanna (1) - 1: Finnish Meteorological Institute, Finland; 2: Case Western Reserve University, USA; 3: Jet Propulsion Laboratory, California Institute of Technology, USA
The operational XCO2 retrieval algorithm of NASA’s Orbiting Carbon Observatory 2 (OCO-2) satellite is based on an optimisation algorithm in which it is assumed that the posterior distribution of the retrieval problem is close to linear near the Maximum a Posteriri (MAP) estimate point, and hence the related uncertainty quantification is made using a multivariate normal distribution. It is, however, well known that the underlying problem is not Gaussian and the uncertainty quantification may be missleading. In this work we investigate the non-linearity and identifiability of the model parameters in the OCO-2 retrieval. This is done using Markov Chain Monte Carlo (MCMC) methods to sample the full multidimensional posterior distribution. We focus on a surrogate forward model, which fits a state vector that consists of CO2 density profile, surface pressure, surface albedo and aerosol moment parameters. We implement a Likelihood Informed Subspace (LIS) dimension reduction scheme to the MCMC sampler in order to reduce the dimension of the problem and speed up convergence of the chain. The sampled MCMC chain represents the multidimensional posterior distribution, which is analysed in detail.
The University of Leicester XCO2 and XCH4 datasets from GOSAT measurements: Support for ESA’s GHG-CCI and Copernicus C3S programmes
Anand, Jasdeep Singh; Parker, Robert; Somkuti, Peter; Boesch, Hartmut - University of Leicester, United Kingdom
The atmospheric concentration of CO2 and CH4 have been defined as Essential Climate Variables (ECV) by the WMO, meaning that they are crucial to our understanding of the Earth’s climate. Satellite observations have provided global coverage which are essential to constraining surface flux estimates and forecasting long-term emission trends. The goal of the ESA GHG-CCI and EU Copernicus C3S programmes is the retrieval, validation, and provision of these datasets to the wider scientific and non-scientific community. As part of these projects, the University of Leicester (UoL) Earth Observation Science group have applied the UoL retrieval algorithms to retrieve the dry-air CO2 (XCO2) and CH4 (XCH4) column mole fractions from near-infrared spectra measured by the JAXA Greenhouse Gases Observing Satellite (GOSAT) to generate global, long-term (2009-2017) datasets..
The UoL ‘full-physics’ retrieval algorithm is a state-of-the-art retrieval based on the Optimal Estimation method. One key feature of the algorithm is that a priori information for aerosols is sourced from data from near real-time forecasts from the ECMWF MACC (now CAMS) aerosol model.
To evaluate the quality of the retrieved products, we validate them against reference data from the terrestrial Total Carbon Column Observing Network (TCCON).
In this presentation, we will give an overview of recent retrieval algorithm developments and the generated CO2 and CH4 ECV datasets. We will discuss their assessment against TCCON observations and comparisons with model calculations, and present plans to expand our algorithm to process data from the new generation of high spatial resolution satellite missions, such as Sentinel 5-P and OCO-2.
A First Look at the Impact of the 2018 Northern Hemisphere Heat Wave on the Carbon Budget as Seen from Space
Marshall, Julia; Gerbig, Christoph - Max Planck Institute for Biogeochemistry, Germany
The summer of 2018 saw unusually high temperatures across much of the northern hemisphere as a result of a weak jet stream, resulting in hot, cloudless regions of high pressure persisting over large areas. Temperatures were significantly higher than usual over swaths of North America, Northeast Asia, and much of Europe. The European heat wave was exacerbated by drought, particularly affecting northern and central Europe, and leading to significant reduction in yields and early harvests in some regions. Fires were also unusually intense and widespread. This has significant effects on the carbon budget, with potential reductions in photosynthesis and increases in respiration and biomass burning emissions expected. With a short latency compared to ground-based measurements, remote sensing data are providing us with a first look at what this means for the carbon dioxide budget. This study uses total column measurements of atmospheric carbon dioxide from OCO-2 and GOSAT until the end of summer 2018, as well as remotely-sensed land surface reflectances from MODIS to derive the prior flux estimates. Fire emissions are estimated from the remote-sensing-driven GFAS near-real-time product. Signals in both concentrations and fluxes are compared to those in previous years, and preliminary inversions are carried out both globally and over a nested domain over Europe. The global inversions allow the continental separation of the flux anomaly, and provide reasonable boundary conditions for the local inversion. Measurements of Solar-induced Fluorescence from OCO-2 are used a posteriori to interpret the flux signal in terms of a partitioning into anomalies in uptake vs. respiration.
Solving Methane Fluxes at Northern Latitudes using Atmospheric and Soil Earth Observations Data
Lindqvist, Hannakaisa; Aalto, Tuula; Tsuruta, Aki; Kivimäki, Ella; Kangasaho, Vilma; Tenkanen, Maria; Rautiainen, Kimmo - Finnish Meteorological Institute, Helsinki, Finland
Novel Earth Observations of atmospheric greenhouse gases and the cryosphere have the potential to fundamentally increase our understanding of the carbon cycle at high Northern latitudes. In this poster, we present our newly started ESA project on quantifying methane (CH4) emissions in the Northern Hemisphere, and investigating their connection to the soil freezing and thawing at boreal latitudes. We combine methods for the quantification of CH4 emissions by applying data from Earth Observing (EO) satellites and global atmospheric methane inversion model estimates. The EO data consist of a global soil freeze/thaw estimate obtained from the ESA Soil Moisture and Ocean Salinity (SMOS) mission as well as retrievals of atmospheric column-averaged methane obtained from the Greenhouse Gases Observing Satellite (GOSAT) and Sentinel 5 Precursor TROPOMI (S5P-TROPOMI) observations. These EO data will be used in global atmospheric methane inversion model, CarbonTracker Europe – CH4, simulations, focusing on (1) the identification of CH4 sources in the Northern Hemisphere and (2) providing trend analysis on the total methane emissions in the past two decades. EO data will be used to assess the spatial variability of the emissions and to better quantify the contributions from regions dominated by anthropogenic emissions and by natural emissions, especially those from wetlands. Further, EO data will be used to create proxies of the seasonality of the natural methane emissions, focusing on the timing and length of the autumn freezing period and springtime melting period.
Improvement of GOMOS Gas and Aerosol Retrieval using AerGOM
Robert, Charles Etienne; Bingen, Christine; Filip, Vanhellemont; Nina, Mateshvili; Emmanuel, Dekemper; Didier, Fussen - BIRA-IASB, Belgium
The simultaneous retrieval of aerosol and trace gases from satellite instruments may suffer from the fact that multiple species are scattering and/or absorbing in the same spectral range. It is especially the case with the Global Ozone Monitoring by Occultation of Stars (GOMOS) mission, where the use of stellar occultation implies a reduced signal-to-noise ratio which makes even more difficult the distinction between the contributions of the different species.
In the framework of EXPANSION, an ESA Living Planet Fellowship project, we explored the performance of the AerGOM retrieval algorithm for the observation of several species (O3, NO2, NO3 and aerosols, and preliminary work for O2 and H2O) from the upper troposphere to the mesosphere using the Global Ozone Monitoring by Occultation of Stars (GOMOS) instrument. AerGOM was initially developed to improve the aerosol extinction coefficient retrieval from GOMOS, more particularly its spectral dependence, but can also be used for the simultaneous retrieval of these gas species, and it is the purpose of EXPANSION to contribute to a better understanding of the way the different gases and aerosols interfere in, and contribute to the retrieval, and to use this knowledge to improve the retrieval for all species.
This presentation will show some of the results obtained in the EXPANSION project, more specifically how various retrieval parameters affect the trace gas inversion. We shall show how trace gases retrievals have been improved through, among other things, a refinement of the absorption cross-sections. A study of the mean residuals also highlight the need for the inclusion of more species to correctly model the GOMOS transmittance and as a result, preliminary work on O2 forward will be presented.
Stratospheric Aerosol Layer in 2011-2018 as Retrieved from Ground-based Twilight Sky Spectral Photometry Above Tbilisi, Georgia.
Mateshvili, Nina (1,2); Fussen, Didier (1); Mateshvili, Iuri (2); Vanhellemont, Filip (1); Bingen, Christine (1); Robert, Charles (1); Paatashvili, Tamar (2); Kyrölä, Erkki (3); Dekemper, Emmanuel (1) - 1: Royal Belgian Institute for Space Aeronomy, Belgium; 2: Abasumani Astrophysical Observatiry,Georgia; 3: Finnish Meteorological Institute,Finland
Aerosol extinction profiles in the upper troposphere - lower stratosphere were retrieved from ground-based measurements of twilight sky brightnesses at 780 and 870 nm wavelengths. The measurements were carried out using a CCD-camera with a grating spectrometer. The retrieval algorithm was based on a fully spherical Monte Carlo radiative transfer code Siro used as a forward model. The measurements covered the period 2011-2018. The aerosol cloud passed above Georgia, South Caucasus in summer 2011 after the Nabro eruption (Eritrea) in June 2011 was observed. The measured enhancements of stratospheric extinctions in summer 2018 may be connected with the eruption of Klyuchevskoy (Russia) in May 2018.
Operational validation of S5P TROPOMI Cloud Height Data
Compernolle, Steven (1); Granville, José (1); Hubert, Daan (1); Keppens, Arno (1); Langerock, Bavo (1); Rasson, Olivier (1); Verhoelst, Tijl (1); Niemeijer, Sander (2); Rino, Bruno (2); Argyrouli, Athina (3); Loyola, Diego (3); Lutz, Ronny (3); Sneep, Maarten (4); O'Connor, Ewan (5); Lambert, Jean-Christopher (1) - 1: Royal Belgian Institute for Space Aeronomy (BIRA-IASB), Brussels, Belgium; 2: s[&]t Corporation, Delft, The Netherlands; 3: German Aerospace Center (DLR), Germany; 4: Royal Netherlands Meteorological Institute (KNMI), De Bilt, The Netherlands; 5: Finnish Meteorological Institute (FMI), Finland
The presence of clouds strongly affects the retrieval of trace gas columns and concentrations from S5P TROPOMI spectral measurements. The near-simultaneous observation of cloud properties by S5P TROPOMI and NPP-VIIRS allows trace gas product providers to properly take these clouds into account.
The Validation Data Analysis Facility (VDAF) of the Sentinel-5p Mission Performance Centre (MPC) aims at providing a routine TROPOMI validation service to ESA, Level-2 data developers, Copernicus services and other data users. It builds upon the heritage of two decades of geophysical validation applications for UV-Vis nadir-viewing instruments (GOME, SCIAMACHY, OMI, GOME-2) and on recent advances in Cal/Val practices and operational validation systems. The VDAF ingests Fiducial Reference Measurements (FRM) archived at ESA’s Validation Data Centre (EVDC) and collected from high-quality ground-based monitoring networks (GAW GO3OS, EARLINET, NDACC, TCCON...), and it compares them to TROPOMI data following community-endorsed protocols. After 9 months of commissioning, the system is now in the routine operations phase.
The S5P-TROPOMI L2_CLOUD product was first released in July 2018, with TROPOMI cloud products starting in November 2017. In this contribution, we present operational validation results of two L2_CLOUD geophysical variables: (i) the cloud top height (CTH), obtained by the S5P OCRA/ROCINN-CAL algorithm, and (ii) cloud height (CH), obtained by the S5P OCRA/ROCINN-CRB algorithm. Both NRTI and OFFL data streams (v1.0.0 and higher), are considered. As it is used in the retrieval of several trace gas data products, the unofficial S5P cloud product L2_FRESCO (v1.0.1 and higher) is also considered in the analysis.
The S5P CLOUD CTH and CH are compared with cloud top height and cloud middle height obtained/derived from the cloud target classification product from the CLOUDNET ground-based network (http://www.cloud-net.org/), itself based on a combination of lidar and radar measurements. The criteria for co-location are motivated, and comparison results are presented, including an analysis of dependences on influence quantities such as cloud fraction, cloud optical thickness, ice/liquid classification, etc. These studies show that S5P ROCINN-CAL CTH and ROCINN-CRB CH values are mostly below the CLOUDNET CTH and CH observations. We find strong correlations (R>0.8) between S5P products and CLOUDNET measurements. Finally, the agreement with the mission requirements for cloud height (systematic error < 20%, random error < 0.5 km or 30 hPa) is verified, taking into consideration that the measured quantities of S5P cloud product on one hand and CLOUDNET on the other hand have not exactly the same meaning. We conclude that the degree of agreement does differ for low clouds vs. high clouds.
Tropospheric Ozone Monitoring With The Infrared Measurements Using A Self-adapting Regularization Method.
Eremenko, Maxim (1); Sgheri, Luka (2); Ridolfi, Marco (3); Cuesta, Juan (1); Dufour, Gaelle (1) - 1: Laboratoire Inter-universitaire des Systèmes Atmosphériques (LISA), UMR7583, Universités Paris-Est Créteil et Paris Diderot, CNRS, Créteil, France; 2: Istituto per le Applicazioni del Calcolo, Consiglio Nazionale delle Ricerche, Firenze, Italy; 3: Dipartimento di Fisica e Astronomia, Università di Bologna, Italy
Lower tropospheric ozone retrievals from nadir sounders is challenging due to the lack of vertical sensitivity of the measurements and towards the lowest layers. If improvements have been made during the last decade, it is still important to explore possibilities to improve the retrieval algorithms themselves. Ozone retrieval from nadir satellite observations is an ill-conditioned problem, which requires regularization using constraint matrices. Up to now, most of the retrieval algorithms rely on a fixed constraint. The constraint is determined and fixed beforehand, on the basis of sensitivity tests. This does not allow ones to take advantage of the entire capabilities of the satellite measurements, which vary with the thermal conditions of the observed scenes. To overcome this limitation, we developed a self-adapting and altitude-dependent regularization scheme. A crucial step is the choice of the strength of the constraint. This choice is done during an iterative process and depends on the measurement errors and on the sensitivity of the measurements to the target parameters at the different altitudes. The challenge is to limit the use of a priori constraints to the minimal amount needed to perform the inversion.
The algorithm has been tested on synthetic observations matching the future IASI-NG satellite instrument. IASI-NG measurements are simulated on the basis of ozone concentrations taken from an atmospheric model and retrieved using two retrieval schemes (the standard and self-adapting ones). Comparison of the results shows that the sensitivity of the observations to the ozone amount in the lowest layers (given by the degrees of freedom for the solution) is increased, which allows a better description of the ozone distribution, especially in the case of large ozone plumes. Biases are reduced and the spatial correlation is improved. Tentative of application to real observations from IASI, currently onboard the Metop satellite will also be presented.
The Effect Of The Potential Vorticity In Validating Satellite Total Ozone Columns Using Ground-based Observations
Paschou, Peristera; Koukouli, MariLiza; Balis, Dimitris - Laboratory of Atmospheric Physics, Aristotle University of Thessaloniki, Greece
The main aim of this study is the improvement of comparisons between satellite and ground-based total ozone column, TOC, measurements in the cases where the collocation criteria result in the observations being affected by the location of the polar vortex. European Space Agency Ozone_CCIGODFIT (GOME-type direct fitting) v4 algorithm retrievals from GOME-2/Metop-A, GOME-2/Metop-B and OMI/Aura TOCs were validated against observations by spectrophotometer instruments (Brewer and Dobson) from the World Ozone and Ultraviolet Radiation Data Centre repository. For the determination of the edge and surface area of the polar vortex, the potential vorticity at 475 K potential temperature surface provided by ERA-Interim reanalysis datasets from the European Centre for Medium-Range Weather Forecasts was used as an indicator.
Ozone observations from 2007 to 2017 were examined for all Brewer and Dobson stations in the North and South Hemisphere with latitude greater than 30o, the regions that are most affected by the position of polar vortex. The analysis was applied for three spatial criteria depending on each satellite’s spatial coverage. The main premise was that the collocations between ground and satellite were separated depending on whether both satellite and ground-based measurements are inside the polar vortex (matched) or one measurement is inside whereas the other one is outside the polar vortex (mismatched).
The results show that the mean difference between mismatched collocations is larger than the mean difference between matched collocations. When allowing for 50 km as radius of collocation, in Vindeln, Sweden (latitude=64.25o N) the mean difference for the mismatched cases is 2.06 ± 0.75 %, 4.18 ± 0.99 % and 1.31 ± 0.28 % for GOME2-A, GOME2-B and OMI respectively, while the mean difference for the matched cases is 1.09 ± 0.03 %, 2.22 ± 0.04 % and 1.5 ± 0.01 % respectively. The number of mismatched collocations that were found to be 11, 3 and 58 for GOME2-A, GOME2-B and OMI respectively, while, the matched collocations are 14874, 5426 and 76216 for GOME2-A, GOME2-B and OMI respectively. Also, by applying a linear regression in the measurements, for the mismatched the slope is 0.97, 0.97 and 0.92 and the intercept is 17.98, 19.84 and 33.74 D.U. for GOME2-A, GOME2-B and OMI respectively, while, for the matched the slope is 1.02, 1.01 and 1.01 and the intercept is -1.43, 3.01 and 1.53 D.U. for GOME2-A, GOME2-B and OMI respectively.
GOP-ECV: A new homogenized ozone profile data record derived from ultraviolet nadir-viewing satellite sensors
Coldewey-Egbers, Melanie (1); Xu, Jian (1); Pedergnana, Mattia (1); Loyola, Diego (1); Latter, Barry (2); Siddans, Richard (2) - 1: German Aerospace Center, Germany; 2: Rutherford Appleton Laboratory, UK
We present the GOME-type Ozone Profile Essential Climate Variable (GOP-ECV) data record that has been compiled from five ultra-violet nadir-viewing satellite sensors GOME/ERS-2, SCIAMACHY/ENVISAT, GOME-2/MetOp-A, GOME-2/MetOp-B, and OMI/AURA. It consists of monthly mean profiles provided on a 5°x10° (latitude x longitude) grid and covers the 22-year period from 1995 to 2017. Level-2 ozone profiles are derived from the individual sensors using the Rutherford Appleton Laboratory (RAL) optimal estimation retrieval scheme, which is a three-step sequential approach. At first, a fit to the sun-normalized radiance in the wavelength region 266-307nm (Hartley band) is performed which yields information on the mid-to-upper stratosphere ozone profile. The second step is the retrieval of an effective surface albedo at 366nm. Both the ozone profile from step one and the albedo from step two contribute to the prior information for the last step, which is a fit in the ozone Huggins bands (323-335nm) in order to obtain accurate information on tropospheric ozone. Before merging the individual time series into one cohesive long-term data record, they are carefully adjusted to match total ozone column amounts from the well-established GOME-type Total Ozone Essential Climate Variable (GTO-ECV) data record generated in the framework of the European Space Agency's Climate Change Initiative (ESA-CCI) ozone project. This procedure leads to reduced inter-sensor biases and drifts. The altitude-dependent scaling of the RAL ozone profiles according to the GTO-ECV total ozone columns is performed using novel machine learning techniques. We compare the new ozone profile data record with other correspondent satellite-based products and discuss perspectives for the estimation of height- and spatially-resolved long-term ozone trends.
Ozone Profile Retrieval Verification for Sentinel-5 UVN
Mettig, Nora; Rozanov, Alexei; Weber, Mark; Burrows, John P. - University of Bremen, Germany
A spectrally and spatially high-resolution nadir viewing UV instrument (UVN) will be on board Sentinel-5 (S5) to be launched in 2021. In preparation for the Sentinel-5 satellite mission, the operational (baseline) UVN ozone profile retrieval will be verified using our (IUP) retrieval algorithm. The vertical ozone distribution in the stratosphere and troposphere is determined from the backscatter spectrum in the ultraviolet spectral range (270 nm - 335nm). The IUP retrieval combines optimal estimation and Tikhonov regularisation and consists of 2 steps: First, the use of the full spectral range to study the entire atmosphere and secondly a consecutive retrieval using only Huggins ozone band ( 322-335 nm) to further improve the tropospheric content similar to the operational algorithm.
For a first application, our adapted ozone profile retrieval has been applied to synthetic data sets using S5 instrument characteristics (spectral resolution, instrument noise). The quality of the IUP algorithm has been tested (uncertainty budget, vertical resolution) and are compared with previously developed algorithms and the operational algorithm. The retrieval error in the stratosphere is about 2% and can increase up to 10% in the troposphere depending on the selected scenario. To test the IUP algorithm, selected orbits from OMI (on AURA) were processed. The evaluation of two exemplary orbits demonstrate the applicability of the retrieval for particularly polluted scenarios and under ozone hole conditions. If feasible, ozone profiles from TROPOMI (on Sentinel-5P) for selected orbits are to be presented as well.
WFDOAS Total Column Ozone Retrieval from OMPS/NPP in preparation for Tropospheric Ozone Retrieval using the Limb-Nadir technique
Orfanoz-Cheuquelaf, Andrea Paz; Weber, Mark; Rozanov, Alexei; Ladstätter-Weißenmayer, Annette - University of Bremen, Germany
Ozone (O3) is one of the most important trace gases in the air, mostly present in the stratosphere, where it is produced naturally, O3 is vital for life on Earth because it protects life from the Sun’s UV radiation. On the other hand, anthropogenic emissions lead to the production of O3 in the lower atmosphere. Around 10% of the total amount of O3 is in the troposphere, where it acts also as a greenhouse gas. Overexposure to this pollutant can cause health problems and damage on vegetation. As an essential climate variable their global concentration and evolution is needed and can only be provided by satellite measurements. Global tropospheric ozone distribution can be derived using the limb-nadir matching technique (LNM), which subtracts the stratospheric column (derived from limb observations) from collocated total column (derived from nadir observations) to obtain the tropospheric column amount up to the tropopause.
SCIAMACHY (2002-2012) was the first instrument that combined both limb and nadir observations in a single instrument. OMPS/NPP (2012-present) has the same capability, which allows us to extend the LNM tropospheric ozone data timeseries. Here we present initial results on the total ozone column from OMPS nadir observations retrieved using the Weighting Function–DOAS (WFDOAS) approach. These data are intended to be combined with the IUP limb ozone data to obtain tropospheric ozone.
Ozone Trends Revisited by Dynamic Linear Model
Kyrölä, Erkki; Sofieva, Viktoria; Laine, Marko - Finnish Meteorological Institute, Finland
Recent years have seen strong activity on determining stratospheric ozone trends in order to find signs of recovery. Some weak positive signs have been detected, but also signs of continuing ozone loss. Satellites are needed to make sound judgments about global trends but trend analysis is still hampered by the short time coverage of measurements. Therefore, new combined and harmonised time series have been constructed that provide better basis for analysis. The analysis of trends is largely based on the use of classical regression approach. The regressors most often used are annual and semi-annual harmonics and proxies for solar UV-radiation, Quasi-Biennial Oscillation and El Nino Southern Oscillation. Trends are retrieved assuming a linear or a piecewise linear trend model.
One alternative to the linear regression is the so-called Dynamic Linear Model (DLM). This model allows the contributions of regressors and trend change at each time step. For ozone trend analysis, this approach was first used by Laine et al. (2014). In this work, we continue this analysis by using the new merged SAGE II, Ozone_cci and OMPS ozone profile dataset (Sofieva et al., 2017). We will provide ozone trends with several time resolutions and study how the prior assumptions of the proxy variables affect the ozone trends.
Ash Plume Detection and Plume Top Height Estimation using SLSTR
Virtanen, Timo Henrik; Kolmonen, Pekka; Sogacheva, Larisa; de Leeuw, Gerrit; Arola, Antti - Finnish Meteorological Institute, Finland
The Sea and Land Surface Temperature Radiometer (SLSTR) instrument aboard Sentinel-3 is used for detection of volcanic ash plumes in atmosphere and for estimating the plume top height. Ash detection is based on the reverse absorption technique using SLSTR channels 8 (10.85 µm) and 9 (12 µm). The height estimates are based on the stereo-viewing capability of SLSTR and on an area-based correlation method approach. The algorithm determines the parallax between the nadir and backward views of SLSTR for an elevated feature, and calculates the corresponding height. It provides height estimates for each satellite pixel with nominal vertical resolution of 0.5 km for the visible channels and 1 km for the thermal infrared channels. The height estimate can be limited to ash-flagged pixels or run for a full scene. The algorithm is capable of retrieving the height of any elevated features with sufficient contrast to the background, such as clouds, ash and dust plumes, thick smoke plumes, or ground surface (for validation). Different wavelengths can be used in the correlation method to obtain complementary information on the feature heights. The SLSTR instrument, orbiting aboard Sentinel-3A since 2016 and on Sentinel-3B since April 2018, provides a unique combination of dual-view capability and a wavelength range from visible to thermal infrared which makes it an ideal instrument for this work. The method has been applied to volcanic eruptions and desert dust plume episodes in 2017 and 2018. The current research is being carried out as part of the H2020 project EUNADICS-AV (European Natural Disaster Coordination and Information System for Aviation).
A new algorithm to retrieve SO2 layer height from UV backscattered measurements: Application to OMI and TROPOMI and comparison with other satellite datasets.
Theys, Nicolas (1); Lerot, Christophe (1); van Gent, Jeroen (1); Brenot, Hugues (1); Clarisse, Lieven (2); Van Roozendael, Michel (1) - 1: Royal Belgian Institute for Space Aeronomy, Belgium; 2: Free University of Brussels – Université Libre de Bruxelles (ULB)
BIRA-IASB has the responsibility of developing the SO2 retrieval algorithm for the Sentinel 5 (S5) UVN prototype processor. While the retrieval of SO2 vertical columns is similar as for TROPOMI/S5P (Theys et al., 2017), the S5 SO2 algorithm also includes an additional module to derive an effective SO2 layer height (LH) which is activated for enhanced SO2 vertical columns (typically >25 DU).
In this paper, we introduce the algorithm, which is based on an iterative SO2 optical depth fitting procedure. Although it makes use of a large look-up-table (of SO2 optical depth spectra), the scheme is adequately fast for an operational environment. We demonstrate the technique based on synthetic spectra and apply the algorithm to OMI and TROPOMI for a number of volcanic eruptions. Results are compared to other satellite datasets, such as CALIOP attenuated backscattered profiles and SO2 height estimates from MLS and IASI. In general, we find an excellent agreement with differences on the retrieved height of less than 1-2 km. The results for TROPOMI are discussed in more details because SO2 plume height data derived at high spatial resolution can provide added-value information on the eruption chronology. Plans for future work, including the possible implementation of a near-real-time SO2 plume height algorithm in the Support to Aviation Control Service (SACS), are addressed.
N. Theys, I. De Smedt, H. Yu, T. Danckaert, J. van Gent,C. Hörmann, T. Wagner, P. Hedelt, H. Bauer, F. Romahn, M. Pedergnana, D. Loyola, M. Van Roozendael :Sulfur dioxide operational retrievals from TROPOMI onboard Sentinel-5 Precursor: Algorithm Theoretical Basis, Atmos. Meas. Tech., 10, 119-153, doi:10.5194/amt-10-119-2017, 2017.
SO2 Plume Height Retrieval: Applying Inverse Learning Machines to GOME-2/MetOp and S5P/TROPOMI SO2 Data
Hedelt, Pascal (1); Efremenko, Dmitry (1); Loyola, Diego (1); Spurr, Robert J.D. (2) - 1: DLR Deutsches Zentrum für Luft- und Raumfahrt, Oberpfaffenhofen, Germany; 2: RT Solutions Inc., Cambridge, USA
Precise knowledge of the location and height of the volcanic sulfur dioxide (SO2) plume is essential for accurate determination of SO2 emitted by volcanic eruptions. Current UV based SO2 plume height retrieval algorithms are very time-consuming and therefore not suitable for near-real-time applications. Here we present a novel method called the Full-Physics Inverse Learning Machine (FP-ILM) algorithm for extremely fast and accurate retrieval of the SO2 plume and apply it to the pre-operational Sentinel-5 Precursor (S5P). S5P was launched on October 13, 2017 carrying the TROPOspheric Monitoring Instrument (TROPOMI), which has a spatial resolution of 7x3.5 km², hence providing an unprecedented level of details.
In this presentation, we introduce the FP-ILM algorithm, which is based on dimensionality reduction techniques and machine learning. We show the first results obtained with the FP-ILM algorithm applied to a selection of volcanic SO2 eruptions detected by TROPOMI and compare them to other plume height datasets available. The sensitivity of the plume height retrieval to various parameters is analyzed as well.
2018 Kilauea eruption followed by Sentinel data
Spinetti, Claudia; Buongiorno, Fabrizia; Lombardo, Valerio; Musacchio, Massimo; Silvestri, Malvina; Colini, Laura - Istituto Nazionale di Geofisica e Vulcanologia, Italy
Active volcanoes are characterized by emitting gas and ash in atmosphere and during eruption the rate increase and can be detectable by satellite sensors. Depending on the size of eruption the volcanic emission can reach the stratosphere and in the troposphere they affect population leaving around volcanic area. In the case of the large Kilauea eruption in Hawaiian Big Inland starting in May 2018 a contextually eruption by 24 lateral fissures and by the summit occurred. In this work we shows the capability in Sentinel 2 and Sentinel 3 to follow the complex Kilauea eruption, detecting the gas and ash plume at the summit and in the ocean entry and mapping the active lava flow. We also retrieve the lava flow field by using Landsat 8 data and to compare it with the Sentinel 2 retrieved one.
Transmission Spectroscopy with the ACE-FTS Infrared Spectral Atlas of Earth: A Model Validation and Sensitivity Study
Schreier, Franz (1); Städt, Steffen (1); Hedelt, Pascal (1); Godolt, Mareike (2) - 1: DLR, IMF, Germany; 2: TUB, ZAA, Germany
ACE-FTS, the Atmospheric Chemistry Experiment - Fourier Transform Spectrometer onboard the Canadian Earth observation satellite "SciSat" is recording solar occultation spectra for about fifteen years. Five infrared atmospheric atlases for arctic summer and winter, midlatitude summer and winter, and the tropics and 31 limb rays (6 - 128 km) have been created by co-adding hundreds of cloud-free infrared spectra (2.2 - 13.3 mue) (Hughes et al., JQSRT 2014). These spectra provide a unique opportunity for model validation and to study the impact of individual molecules, spectral resolution, molecular spectroscopy data (HITRAN, GEISA, continua, etc.), and auxiliary data. Here we use GARLIC - Generic Atmospheric Radiative Transfer Line-by-Line Infrared Code (Schreier et al., JQSRT 2014) and compare observed and modeled "effective height spectra" obtained by integrating (summming) the entire limb sequence. This kind of spectra are typically used for remote sensing of (exo-)planetary atmospheres by transit spectroscopy, where only disk-averaged observations are possible.
The Earth effective height spectrum varies between a few kilometers (in atmospheric window regions) and about 50 km in the CO2 v2 and v3 bands with small variations due to season and latitude. The largest impact on the transit spectra is due to water, carbon dioxide, ozone, methane, nitrous oxide, nitrogen, nitric acid, oxygen, and some chlorofluorocarbons (CFC11 and CFC12). The effect of further molecules considered in the modeling is either marginal or absent. The impact of spectroscopic input data on the model spectra is small. The best matching model with 17 molecules absorbing has a mean residuum of 0.4 km and a maximum difference of 2 km to the measured effective height.
Trends of Minor Atmospheric Gases Evaluated Using MIPAS V8 Products
Pettinari, Paolo (1); Dinelli, Bianca Maria (1); Raspollini, Piera (2); Ridolfi, Marco (3,4); Valeri, Massimo (5); Zoppetti, Nicola (1) - 1: ISAC-CNR, Bologna - Italy; 2: IFAC-CNR, Florence - Italy; 3: INO-CNR, Florence - Italy; 4: University of Bologna, Bologna - Italy; 5: 3-B Meteo, Italy
MIPAS (Michelson Interferometer for Passive Atmospheric Sounding), a limb-viewing infrared interferometer, operated on-board the ENVISAT satellite from 2002 to 2012. In the past years a huge effort was performed in correcting the time dependent non-linear response of its detectors, in order to produce calibrated measurements stable in time. The new calibration strategy has been implemented into the latest version (V8) of the Level 1 processor. Also the Level 2 (L2) processor has been upgraded, the main improvements being the handling of horizontal gradients and the use of an upgraded spectroscopic database. Both new processors have been used to generate three Diagnostic Datasets. The new L2 datasets contain the vertical distributions of Temperature and the VMR of H2O, O3, HNO3, CH4, N2O, NO2, CFC-11, CFC-12, N2O5, ClONO2, HCFC-22, COF2, CF4, HCN, CCl4, OCS, CH3Cl, HDO, C2H2, C2H6, and COCl2.
For each month of MIPAS lifetime, the data have been averaged in latitudinal bins at fixed pressure levels, and for each level, trends have been estimated using the same method described in Valeri et al. (2017). In this paper we will show some examples of the estimated trends, concentrating on reactive molecules like phosgene.
Valeri, M., Barbara, F., Boone, C., Ceccherini, S., Gai, M., Maucher, G., Raspollini, P., Ridolfi, M., Sgheri, L., Wetzel, G., and Zoppetti, N.: CCl4 distribution derived from MIPAS ESA v7 data: intercomparisons, trend, and lifetime estimation, Atmos. Chem. Phys., 17, 10143-10162, https://doi.org/10.5194/acp-17-10143-2017, 2017
Ground-based Assessment of the V8 Reprocessing of ESA's Envisat MIPAS Geophysical Data Products
Hubert, Daan (1); Keppens, Arno (1); Granville, José (1); Lambert, Jean-Christopher (1); Raspollini, Piera (2); Dehn, Angelika (3) - 1: Royal Belgian Institute for Space Aeronomy (BIRA-IASB), Brussels, Belgium; 2: IFAC-CNR, Florence, Italy; 3: ESA/ESRIN, Frascati, Italy
Infrared observations of the Earth’s limb by the MIPAS instrument on Envisat have contributed a unique data record to study physical and chemical processes in the atmosphere between 2002 and 2012. MIPAS spectra contain the information to infer accurate vertical profiles of air pressure, temperature and volume mixing ratio of more than 20 trace gases from cloud top well into the mesosphere. Over the past few years the chain of ESA's operational Level-1b and Level-2 processors was further developed and it now entered a phase of comprehensive testing and validation by the MIPAS Quality Working Group. This upgraded MIPAS chain is labelled V8 and it includes, e.g., (a) updated spectroscopic data, (b) revised non-linearity coefficients and an improved pointing correction model (Level-1b), and, (c) the handling of horizontal inhomogeneities in the retrieval of geophysical quantities (Level-2). Such changes potentially have an important impact on the quality of the Level-2 data products: their bias, precision or long-term stability, and their dependence on geophysical parameters.
Here, we present the results of a delta-validation study of the altitude registration and of five primary MIPAS Level-2 data products (temperature, O3, HNO3, CH4 and N2O). Our analyses are based on comparisons of ~10% of the MIPAS data record to co-located ground-based observations by ozonesonde, temperature and ozone lidar, microwave radiometer and FTIR instruments operating within monitoring networks contributing to WMO's Global Atmospheric Watch (GAW), such as the Network for the Detection of Atmospheric Composition Change (NDACC) and the Southern Hemisphere ADditional OZonesonde programme (SHADOZ). We performed comprehensive studies of the structure of MIPAS bias and short-term variability in the spatial (vertical, latitudinal) and in the temporal domain at various scales. Estimates of these quality indicators on the partial data record have proven in the past to be reliable and they reflect what is later on obtained once the entire mission is reprocessed. These first results for the upcoming V8 reprocessing are then compared to those obtained for earlier MIPAS processor chains in order to verify whether the Level-2 data quality evolves according to expectations.
SCIAMACHY L2 Ground Processor Version 7 Phase F Re-processing
Lichtenberg, Günter (1); Meringer, Markus (1); Gretschany, Sergei (1); Hamidouche, Mourad (1); Schreier, Franz (1); Doicu, Adrian (1); Theys, Nicolas (2); Lerot, Christophe (2); Eichmann, Kai-Uwe (3); Noël, Stefan (3); Dehn, Angelika (4) - 1: German Aerospace Centre (DLR), Germany; 2: Belgian Institute for Space Aeronomy (IASB-BIRA), Brussels, Belgium; 3: Institute of Environmental Physics / Remote Sensing (IUP/IFE), University of Bremen, Bremen, Germany; 4: ESA-ESRIN
SCIAMACHY (SCanning Imaging Absorption spectroMeter for Atmospheric ChartographY) aboard ESA's environmental satellite ENVISAT observed the Earth's atmosphere in limb, nadir, and solar/lunar occultation geometries covering the UV-Visible to NIR spectral range. It is a joint project of Germany, the Netherlands and Belgium and was launched in February 2002. SCIAMACHY doubled its originally planed in-orbit lifetime of five years before the communication to ENVISAT was severed in April 2012, and the mission entered its post-operational phase.
In order to preserve the best quality of the outstanding data recorded obtained by SCIAMACHY, the data processors were updated in phase F and the whole mission was reprocessed. In addition to the usual updates, the following items were added to the processor
1. Tropospheric BrO, a new retrieval based on the scientific algorithm of (Theys et al., 2011). This algorithm had been originally developed for the GOME-2 sensor and later adapted for SCIAMACHY.
2. Improved cloud flagging using limb measurements. Limb cloud flags are already part of the SCIAMACHY L2 product. They are currently calculated based on the scientific algorithm by (Eichmann et al., 2015). Clouds are categorized into four types: water, ice, polar stratospheric and noctilucent clouds.
3. A new, future-proof file format for the level 2 product based on NetCDF.
We will present results from the verification and the mission re-processing.
SCIAMACHY: Level 0-1 Processor V9 and Phase F Re-processing
Lichtenberg, Günter (1); Slijkhuis, Sander (1); Aberle, Bernd (1); Meringer, Markus (1); Noël, Stefan (2); Bramstedt, Klaus (2); Hilbig, Tina (2); Liebing, Patricia (2,3); Bovensmann, Heinrich (2); Snel, Ralph (4,5); Krijger, Matthijs (4,6); Dehn, Angelika (7) - 1: German Aerospace Centre (DLR), Germany; 2: Institute of Environmental Physics / Remote Sensing (IUP/IFE), University of Bremen, Bremen; 3: now at Leiden Observatory, 2300 RA Leiden, the Netherlands; 4: SRON, Netherlands Institute for Space Research, Utrecht, The Netherlands; 5: now at TNO, Delft, The Netherlands; 6: now at Earth Space Solutions, Utrecht, the Netherlands; 7: ESA/ESRIN, Italy
SCIAMACHY (SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY) is a scanning nadir and limb spectrometer covering the wavelength range from 212 nm to 2386 nm in 8 channels. It is a joint project of Germany, the Netherlands and Belgium and was launched in February 2002 on the ENVISAT platform. After the platform failure in April 2012, SCIAMACHY is now in the postprocessing phase F. Its originally specified in-orbit lifetime was double the planned lifetime. SCIAMACHY was designed to measure column densities and vertical profiles of trace gas species in the mesosphere, in the stratosphere and in the troposphere (Bovensmann et al., 1999). It can detect a large amount of atmospheric gases (e.g. O3 , H2CO, CHOCHO, SO2 , BrO, OClO, NO2 , H2O, CO, CH4 , among others ) and can provide information about aerosols and clouds.
The operational processing of SCIAMACHY is split into Level 0-1 processing (essentially providing calibrated radiances) and Level 1-2 processing providing geophysical products.
The operational Level 0-1 processor has been completely re-coded and embedded in a newly developed framework that speeds up processing considerably. In the frame of the SCIAMACHY Quality Working Group activities, ESA is continuing the improvement of the archived data sets. Version 9 of the Level 0-1 processor includes
The new format for the Level 1b and Level 1c will be netCDF V4. We will present the verification results and the results of the mission re-processing.
One Year of S5p/TROPOMI Glyoxal Retrievals
Lerot, Christophe (1); De Smedt, Isabelle (1); Theys, Nicolas (1); Yu, Huan (1); Vlietinck, Jonas (1); Van Roozendael, Michel (1); Stavrakou, Jenny (1); Müller, Jean-François (1); Lampel, Johannes (2); Alvarado, Leonardo (3); Richter, Andreas (3) - 1: BIRA-IASB, Belgium; 2: IUP-Heidelberg, Germany; 3: IUP-Bremen, Germany
The TROPOspheric Monitoring Instrument (TROPOMI) has been launched on October 13, 2017, aboard the polar orbiting platform Sentinel-5 Precursor (S5p). TROPOMI measures the Earth's radiance in the ultraviolet, visible, near and short-wave infrared spectral ranges with an unprecedented spatial resolution of 7x3.5km², providing important information on natural and anthropogenic emissions of trace gases and aerosols. Although currently not part of the suite of operational products, glyoxal tropospheric columns can be retrieved from TROPOMI measurements in the visible spectral range. Such retrievals remain challenging owing to the low glyoxal optical depths but offer the potential to provide additional quantitative information on VOC emissions.
The BIRA-IASB glyoxal algorithm, successfully applied in the past to GOME-2A/B and OMI, has been transferred to TROPOMI and we present here results of its application to one year of measurements. Based on comparisons with OMI retrievals, we illustrate the benefit of the excellent TROPOMI spatial resolution and signal-to-noise ratio to better identify and characterize the sources of this tropospheric trace gas. As part of the Sentinel-5 level-2 prototype processor development, we revisit the impact of uncertainties on water vapor absorption, a major interfering species for glyoxal retrieval. Verification activities involving the independent scientific algorithm developed at University of Bremen are finally presented using both synthetic and real S5p spectra.
Retrieval of total column densities of formaldehyde and sulphur dioxide from Sentinel-4 measurements.
van Gent, Jeroen; Theys, Nicolas; Yu, Huan; De Smedt, Isabelle; Lerot, Christophe; Van Roozendael, Michel - Royal Belgian Institute for Space Aeronomy, Belgium
We present the L1 > L2 prototype algorithms for formaldehyde (HCHO) and sulphur dioxide (SO2) total column density that have been developed in the framework of the ESA S4-L2 project in preparation of the Sentinel-4 mission. Sentinel-4 is an operational satellite foreseen for launch in the early 2020’s. It will be the first mission to monitor trace gas column densities and aerosol over Europe from a geostationary perspective.
For HCHO the mission is of high interest as the hourly revisit time will allow to better study the diurnal variation of HCHO columns, which is for the moment poorly known.
For SO2, it is expected that Sentinel-4 measurements will be able to detect low levels of anthropogenic SO2 and improve on the existing satellite data sets due to the combination of high spatial resolution (8x8 km²) and high temporal sampling (1 hour). These aspects are also of value in the monitoring of volcanic plumes.
In this paper, we will address the specific challenges posed to the algorithms for both trace gases when observing in a geostationary geometry and discuss the new developments and performance with respect to existing algorithms for polar orbiters.
A DOAS Based Total Column Water Vapour Retrieval for Climate Change Studies
Köhler, Claas H.; Valks, Pieter; Slijkhuis, Sander - Deutsches Zentrum für Luft- und Raumfahrt (DLR), Germany
Water vapour is an essential climate variable. Thus it is important to generate consistent long term records of the atmospheric water vapour content for the ongoing monitoring and analysis of climate change on earth. We present first results from a DOAS retrieval of total column water vapour (TCWV) in the blue wavelength region (420-470 nm). While the optical depth of water vapour in this retrieval window is much lower than that in other frequently used retrieval windows, the blue window offers a few distinct advantages. The most important reason to choose this window, is that it is covered by many recent and upcoming satellite instruments including GOME, SCIAMACHY, GOME-2, OMI, TROPOMI and the upcoming Sentinel-4 and Sentinel-5 missions. Thus the blue retrieval window is very well suited to create long term records tailored for climate research, because the same algorithm can be used for a variety of instruments. This approach reduces the probability for algorithm dependent bias in the product derived for one mission. We present first results obtained with the DOAS approach in the blue wavelength region using TROPOMI data. The results of selected datasets are validated against reference data acquired by radiosondes. Furthermore a comparison to ECMWF model data will be performed. Additionally we show a comparison of results obtained with the proposed retrieval in the blue wavelength region with results from the operational GOME-2 TCWV product derived in the red region of the visible spectrum (610- 690 nm) within the scope of our AC-SAF work.
14-year space born chlorophyll-a observations in the Mediterranean Sea and the Atlantic Ocean and its underlying correlation with physical and chemical variables.
Koukouli, Maria Elissavet
Skoulidou, Ioanna; Koukouli, Maria Elissavet; Balis, Dimitrios - Laboratory of Atmospheric Physics, Aristotle University of Thessaloniki, Thessaloniki, Greece
Phytoplankton form important parameters as far as the climate and the life in the oceans are concerned, firstly by affecting the global carbon cycle and the planetary heat budget and additionally by forming the base of the marine food chain. The proposed study addresses the determination of patterns in chlorophyll-a concentrations, as an index of the phytoplankton biomass, and the underlying correlation to distinct physical-chemical variables in different areas of the ocean.
Satellite sea surface chlorophyll-a monthly observations are derived from the ESA Ocean Colour Climate Change Initiative (OC-CCI) with a spatial resolution of 4 km for a 14-year period (2003 - 2016) and for four different areas, which are later separated in sub-regions according to the chlorophyll-a variability patterns. The four different areas are situated in the Mediterranean Sea (Adriatic Sea, Levantine Sea and West Mediterranean Sea) and in the Atlantic Ocean (the Gulf of Biscay). For the same areas satellite and model data are processed. The satellite data acquired are the Sea Surface Temperature (SST) and the Photosynthetically Active Radiation (PAR) measured by the MODIS instrument. The model derived data used are the nitrate and phosphate concentrations obtained by models from the Copernicus Marine Environmental Monitoring Service and dust deposition for the area of the Levantine Sea acquired by the NASA atmospheric reanalysis, MERRA-2.
Higher concentrations of chlorophyll-a are found in the coastal sub-regions of the four previously mentioned areas, and mostly in waters affected by river discharges that contain nutrients that vary in response with the amount of the precipitation and the anthropogenic factor (i.e. industry, agriculture, different lifestyles). Great discrepancies, mostly in the chlorophyll-a and the nutrients variability, are shown between the sub-regions and different trends are calculated throughout the period of study. The correlations between the chlorophyll-a and the other variables demonstrate a great variation between the sub-regions. Maps, plots, correlations and trends will be presented.
TROPOMI as a Crucial Link for measuring Sun-Induced Fluorescence
Kooreman, Maurits (1); Stammes, Piet (1); Veefkind, Pepijn (1); Boersma, Folkert (1,2) - 1: Royal Netherlands Meteorological Institute; 2: Wageningen University and Research
Chlorophyll fluorescence is the re-emittance of solar radiation at higher wavelengths by vegetation. It originates from the internal processes in leaves during photosynthesis. Since a few years, it has been shown by several researchers that sun-induced fluorescence (SIF) can be retrieved from satellite spectrometers measuring in the near-infrared, from about 640-780 nm. This fluorescence information is useful to constrain the actual photosynthesis rate of the global vegetation. Since there is a close connection between photosynthesis and gross primary production (GPP) of vegetation, SIF measurements may help to better quantify and understand the uptake of CO2 by the terrestrial biosphere.
The SIF retrieval algorithm that we use at KNMI for GOME-2 is based on the work by Joiner et al. (AMT, 2013) was adapted by Sanders et al. (AMT, 2016). The GOME-2 instrument has a good spectral coverage and resolution but a relatively large pixel size of 40x80 km2. Based on simulated top-of-atmosphere spectra with a known fluorescence signal we have performed sensitivity studies of SIF retrievals. This led to several algorithm improvements. Recent results of application of our SIF algorithm to GOME-2 data shows a better correlation with other space-born vegetation products. Especially the fluorescence signals of tropical forests are better captured. Also the improved retrieval algorithm is able to pick up regional reductions in fluorescence which coincide with severe drought events. Currently, in the EUMETSAT Satellite Application Facility on Atmospheric Composition Monitoring we are working towards operationalizing this SIF retrieval for GOME-2 on the MetOp-A/B/C satellite series.
The new TROPOMI instrument on the Sentinel-5P satellite, launched in October 2017, also has a near-infrared channel capable of measuring SIF. Because of its daily global coverage and high spatial resolution of 3.5x7 km2, i.e. more than two orders of magnitude better than GOME-2, a TROPOMI SIF product would be very useful for the global carbon modeling community and would provide insight in local carbon fluxes . TROPOMI would be bridging the gap in spatial resolution between GOME-2 and the FLEX mission, which is the ESA Earth Explorer mission planned for 2022, having a resolution of 300 m. Here we will present our plans for adapting the SIF algorithm for TROPOMI and first experiments.
On a problem related to sizing the cloud droplets using the Cloud Aerosol Spectrometers for in situ measurements
Vâjâiac, Nicolae Sorin (1); Calcan, Andreea (1); Moacă, Denisa Elena (1); Valeriu, Filip (1,2) - 1: National Institute for Aerospace Research "Elie Carafoli" INCAS - Bucharest, Romania; 2: University of Bucharest, Faculty of Physics, 405 Atomistilor Str., Magurele 077125, P.O. BOX MG-11, Romania
Understanding the micro-physical processes that take place in clouds requires the knowledge of improved size distribution of the cloud droplets. To this purpose, in situ measurements using the Cloud Aerosol Spectrometers (CAS) prove to be very useful tools if some procedural clarifications are made. This paper proposes to fix some problems of size estimation from CAS outputs. The measuring principle of the instrument is based on analysing the forward single scattering of light by cloud particles. The estimation of size droplet is possible through conversion of the scattering cross section by droplet in particle diameter through the Mie formalism. Any droplet between 0.5-50 µm, which is the size range of the instrument, will have a scattering cross section that is a function of diameter. The Mie theory is used to estimate the theoretical curve used to correlate the droplet size with scattering cross section. An important hurdle is that the computed diagram is not smooth and for many values of scattering cross section can correspond 2 or 3 diameters. In this situation, the size range (0.5-50 µm) of the CAS will be divided in smaller size intervals, called bins in the literature. To generate these bins, an important issue is the number of diameters used to evaluate the scattering cross section (Nd). As this number increases, the curve that makes the conversion between scattering cross section and diameter becomes noisier and severely affects (usually decreases) the number of bins that can be generated. The method was applied on a data set of a CAS instrument, recorded during a flight with a Beechcraft C90 GTx in a water cloud in the southern part of Romania. We expect that the method can be extended to other particle types like ice crystals and aerosol.
Ground-Based Assessment Of The SCIAMACHY L2 SGP V7 Full Mission Dataset And Its Evolution With Respect To Preceding Processor Versions
Keppens, Arno (1); Hubert, Daan (1); Hendrick, François (1); Granville, José (1); Lambert, Jean-Christopher (1); Lichtenberg, Günter (2); Noël, Stefan (3); Dehn, Anglika (4) - 1: Royal Belgian Institute for Space Aeronomy (BIRA-IASB), Brussels, Belgium; 2: German Aerospace Center (DLR), Oberpfaffenhofen, Weßling, Germany; 3: Institute of Environmental Physics / Remote Sensing (IUP/IFE), University of Bremen, Germany; 4: ESA/ESRIN, Rome, Italy
ESA’s Envisat satellite has provided an important contribution to the global atmospheric composition monitoring from 2002 to 2012. The SCIAMACHY (SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY) instrument is one of the three on-board passive remote sensing spectrometers that enabled measuring the abundance of a variety of trace gases and parameters, including reactive and greenhouse gases. Envisat operations currently reside in post-flight Phase F, and the product evolution cycle implemented by ESA with the support of the SCIAMACHY Quality Working Group has reached the stage of data reprocessing and validation. In the independent data quality assessment and validation, the uncertainties and geophysical consistency of the data must be assessed for the wider range of atmospheric states and over the relevant spatial domain, vertical range, and mission lifetime. Every upgrade of the data products and associated data processors must moreover be verified through delta-validation studies of the expected improvement. The outcome of these delta-validation studies provides valuable feedback to the respective data retrieval teams.
This work reports on the quality assessment of the evolution of operational SCIAMACHY L2 data products that include the nadir-observed vertical column of O3, NO2, BrO, CO, CH4, and H2O, and the limb profile measurement of O3 and BrO. Validation analyses are based on comparisons to co-located ground-based observations by ozonesonde, lidar, DOAS spectrometers, FTIR instruments, and microwave radiometers operating within the Network for the Detection of Atmospheric Composition Change (NDACC), WMO's Global Atmospheric Watch (GAW) and the Southern Hemisphere ADditional OZonesonde programme (SHADOZ). These networks provide well-characterized data records of different atmospheric constituents with appropriate accuracy and spatio-temporal sampling and resolution properties. Correlative studies yield estimates of the SCIAMACHY bias, spread, long-term stability, and their dependence on geophysical parameters.
The focus of this validation exercise is on the latest SGP V7 processor full mission data and its improvement with respect to previous operational products. It is verified whether the quality of the V7 data is similar to that of the previous SGP V6.01 and V5.02 processors for all studied products, as suggested by a delta-validation study on a diagnostic dataset of selected orbits. The delta-validation pointed to vertical oscillations (order of a few percent) in the V7-V6 difference limb ozone profiles, and a 20-40 % decrease in the V7 nadir methane columns with respect to V6, related to the changes in the V9 Level-1 processor. In this work these results are being reconsidered by validation of the complete SGP V7 reprocessing. For other products and quality indicators no degradation is expected, but not a substantial improvement either.
Design and Development Overview of the Airborne Multi-wavelength, Multi-depolarization High Spectral Resolution Lidar
Belegante, Livio (1); Serikov, Ilya (2); Nicolae, Doina (1); Linne, Horger (2); Brugmann, Bjorn (2); Worbes, Ludwig (2); Amiridis, Vassilis (3) - 1: INOE, Romania; 2: Max Planck Institute for Meteorology, Germany; 3: National Observatory of Athens, Greece
The paper presents an overview of the design study and current developments for an airborne multi-wavelength HSRL system, to be installed on board of a Hawker Beechcraft King Air C90-GTx aircraft under the second phase of project implementation. The system is meant to deliver the aerosol extinction, backscatter and depolarization profile distributions in IR, VIS and UV spectral range for the ESA Cal/Val activities. Interferometer based filtering technique is identified to be a feasible approach for UV and IR range, while for VIS, the Iodine cell approach was concluded to be most reliable. The work is carried out and financed by the ESA project Multiply, 4000112373/14/NL/CT
Near-ground Wind Speed Profile of the Bora Wind
Bervida, Marija (1); Stanič, Samo (1); Bergant, Klemen (1,2) - 1: University of Nova Gorica, Slovenia; 2: Slovenian Environment Agency, Slovenia
Bora is cold and gusty downslope wind with variable gust frequency and duration, appearing on the lee side of Dinaric Alps. Its flow characteristics are unique and theoretically still not fully described, especially for modeling purposes. We present an analysis of the wind speed vertical profiles at Razdrto, which lies in a gap between the Nanos and Javorniki plateau in southwest Slovenia and is strongly exposed to Bora. An analysis of the vertical wind speed profiles during Bora episodes is based on experimental wind data, provided by Helikopter energija, for six Bora events of different duration, appearing between April 2010 and May 2011. Average wind speed in 10-minute intervals was collected at four different heights (20, 31, 40 and 41.7 m above the ground)at the wind turbine site in Razdrto using cup anemometers. Wind direction data with same temporal resolution was obtained from a single wind vane placed at 40.9 m above the ground. Based on the collected data, the applicability of the empirical power-law and the logarithmic law profiles, commonly used for the description of neutrally stratified atmosphere, was investigated for the case of Bora. The parameters for the power-law and logarithmic law were obtained by fitting the wind speed data using linear regression method and are compared to standard values for that particular type of terrain. The quality of fits was very good with r2 above 0.9, indicating that both power-law and logarithmic law adequately describe mean horizontal Bora wind. The median value of the power-law coefficient was found to be 0.16±0.03, which is consistent with standard value for neutral atmosphere (0.143). The aerodynamic roughness varied from 0.003 m to 0.22 m with the median value of 0.09±0.07, which describes open level country terrain with some trees. The event in November 2010 with large roughness is expected to be due to specific wind direction and surface conditions.
High-resolution temperature profiles (HRTP) retrieved from bi-chromatic stellar scintillation measurements by GOMOS/Envisat
Sofieva, Viktoria (1); Dalaudier, Francis (2); Hauchecorne, Alain (2); Kan, Valery (3) - 1: Finnish Meteorological Institute, Finland; 2: Université Versailles St-Quentin, Sorbonne Université, CNRS/INSU, LATMOS-IPSL, Guyancourt, France; 3: A.M. Obukhov Institute of Atmospheric Physics, Moscow, Russia
In this presentation, we discuss the inversion algorithm for retrievals of high vertical resolution temperature profiles using bi-chromatic stellar scintillation measurements in the occultation geometry. This retrieval algorithm has been improved and applied to the measurements by Global Ozone Monitoring by Occultation of Stars (GOMOS) operated on board Envisat in 2002-2012. The retrieval method exploits the chromatic refraction in the Earth atmosphere. The bi-chromatic scintillations allow the determination of refractive angle, which is proportional to the time delay between the photometer signals. The paper discusses the basic principle and detailed inversion algorithm for reconstruction of high resolution density, pressure and temperature profiles (HRTP) in the stratosphere from scintillation measurements. The HRTP profiles are retrieved with very good vertical resolution ~200 m and high accuracy ~1-3 K for altitudes 15-32 km and a global coverage. The best accuracy is achieved in vertical (in orbital plane) occultations, and the accuracy weakly depends on star brightness. The whole GOMOS dataset has been processed with the improved HRTP inversion algorithm using the FMI’s Scientific Processor; and the dataset (HRTP FSP v1) is in open access.
The validation of small-scale fluctuations in the retrieved HRTP profiles is performed via comparison of vertical wavenumber spectra of temperature fluctuations in HRTP and in collocated radiosonde data. We found that the spectral features of temperature fluctuations are very similar in HRTP and collocated radiosonde temperature profiles.
HRTP can be assimilated into atmospheric models, used in studies of stratospheric clouds and in analysis of internal gravity waves activity. As an example of geophysical applications, gravity wave potential energy has been estimated using the HRTP dataset. The obtained spatio-temporal distributions of gravity wave energy are in good agreement with the previous analyses using other measurements.
Re-calibrated Solar Spectral Irradiance (SSI) from the Satellite Instrument SCIAMACHY
Hilbig, Tina; Weber, Mark; Bramstedt, Klaus; Burrows, John P. - Institute of Environmental Physics, University of Bremen, Germany
Accurate knowledge of solar variability on longer timescales is important for improving our understanding of their contribution to climate variability. SCIAMACHY (Scanning Imaging Absorption spectroMeter for Atmospheric CHartographY) on-board Envisat performed daily Sun observations for nearly a decade from 2002-2012 covering the UV-vis-NIR spectral range (212-1760 nm and two narrow bands from 1930-2040 nm and 2260-2380 nm).
Recent developments in the SCIAMACHY calibration (e.g. a physical model of the scanner unit including degradation effects and an on-ground to in-flight correction using the on-board white light source) are used to provide a new SCIAMACHY solar reference spectrum. Detailed comparisons with several other established solar reference spectra show good agreement to within 3 % for most parts of the visible and NIR spectral range from about 350 to 1500 nm.
Special emphasis was placed on the spectral region above 1500 nm. In the NIR the various SSI reference data do not agree within their confidence interval and this led to a controversial debate (e.g. Bolsee et al., 2014; Thuillier et al., 2015; Weber, 2015; Bolsee et al., 2016; Elsey et al., 2017; Gröbner et al., 2017). The re-calibration of SCIAMACHY SSI shows a deficit of 4-8 % with respect to the ATLAS-3 composite (Thuillier et al., 2004) and WHI (SORCE/SIM) reference spectrum (Woods et al., 2009). In contrast, SCIAMACHY matches very well (above 400 nm) the SOLAR-ISS (Meftah et al., 2018) and new ground-based measurements from Mauna Loa (Pereira et al., 2018). There is now increasing evidence that the ATLAS-3 composite seems to be high biased in the NIR.
The new SCIAMACHY solar reference spectrum is the first step towards a 10 years time series of solar spectral irradiance data. This presentation will also summarise the revised degradation correction scheme that is necessary to study SSI trends and variability on different time scales.
Global Surface Solar Radiation Product Derived From SCIAMACHY And OMI Satellite Measurements
Wang, Ping; van Lammeren, Joris; Stammes, Piet - Royal Netherlands Meteorological Institute, Netherlands, The
Surface solar radiation products derived from polar orbiting satellite measurements
provide a global mapping of solar radiation at the Earth’s surface. These products
are very useful for solar resource assessments because of its global coverage and
consistency. We have developed an operational surface solar irradiance product for
SCIAMACHY and OMI satellite spectrometers. The SCIAMACHY overpass time was in the
morning at about 10.00 LT (2002-2012), while the OMI overpass time is in the afternoon
close to 13:30 LT (2004-). Recently we combined the SCIAMACHY and OMI solar radiation
products and made the daily mean monthly mean surface solar radiation
products at 0.25 degree x 0.25 degree (latitude x longitude) grid. The daily mean
monthly mean surface solar radiation is often used in solar energy models.
The SCIAMACHY and OMI daily orbit SSI products have been evaluated using the
Baseline Surface Radiation Network (BSRN) measurements. The daily mean month mean
surface solar radiation data have been compared with CERES monthly mean product and
validated using the BSRN measurements. The algorithm can also be applied to
GOME-2 (morning orbit) and OMI/TROPOMI (afternoon orbit). In this presentation we
will explain the algorithm and show some examples of the products.
Long-Time Series Aerosol Optical Depth Retrieval From AVHRR Data Over Land In North China And Central Europe
Xue, Yong (1); che, Yahui (2); Guang, Jie (2) - 1: University of Derby, United Kingdom; 2: RADI/CAS
An algorithm for the retrieval of the aerosol optical depth over land (ADL) using radiances at the top of the atmosphere (TOA) measured by the Advanced Very High Resolution Radiometer (AVHRR) is proposed. AVHRR is the only satellite sensor providing nearly continuous global coverage since June 1979, which could generate the longest aerosol climate data records currently available from operational satellites. In the implementation of the ADL algorithm, an analytical model is used which couples an atmospheric radiative transfer model and a land surface reflectance parameterization. The radiation field can be separated into three parts: direct radiance, single-scattered radiance, and multiple-scattered. Each of these parts is individually parameterized. To obtain the surface reflectance in an automatic retrieval procedure over land for AVHRR, the aerosol scattering effect at 3.75 μm was assumed to be negligible and relationships between the surface reflectances at 0.64 μm and 3.75 μm were evaluated for different surface types and the authors propose to use these to obtain the surface reflectance at the shorter wavelength. The 0.64 μm surface reflectance was then used in a radiative transfer model to compute AOD at that wavelength using six different aerosol types, where optimal estimation (OE) theory is applied to minimize the difference between modeled and measured radiances. The ADL algorithm is applied to re-calibrated Level 1B radiances from the AVHRRs on-board the TIROS-N and the Metop-B satellites to retrieve the AOD over North China and Central Europe. The results show that the AOD retrieved from these two instruments are in agreement with co-located AOD values from ground-based reference networks. Over North China, using AERONET sites, 58% of the ADL AOD values are within an expected error (EE) range of ±(0.05 + 20%) and 53% are within the EE range of ±(0.05 + 15%). For GAW-PFR (World Meteorological Organization, WMO, Global Atmosphere Watch, GAW) sites, part of the European ACTRIS (Aerosols, Clouds, and Trace gases Research InfraStructure) sites, 79% of the ADL AOD values are within the EE range of ±(0.05 + 20%) and 75% are within the EE range of ±(0.05 + 15%). Not surprisingly, the agreement is better over Europe with generally lower AOD values. An additional cross comparison of the AOD results with MODIS (MODerate-resolution Imaging Spectroradiometer) DeepBlue aerosol products shows that the spatial distributions of the two AOD datasets are similar, but with generally lower values for ADL and lower coverage. The temporal variation of the annual mean AOD over selected AERONET sites shows that ADL values are generally between 0.2 and 0.5 over North-Eastern China and trace the MODIS and AERONET data for the overlapping years quite well.
Speeding up the DISORT solver: mathematical approach and application to radiance simulations of FORUM
Sgheri, Luca (1); Castelli, Elisa (2) - 1: IAC CNR, Italy; 2: ISAC CNR, Italy
New remote sensing satellite sensors for the measurements of atmospheric radiation offer the advantage of very high spectral resolution and spectral and/or spatial and temporal coverage. The analysis of these measurements often requires a forward model (FM) for the simulation of the radiation collected by the sensor. The FM should model all the processes affecting the radiance, such as absorption and scattering by molecules and particles.
Despite the advancement in sensor technology, the radiative transfer solvers are almost the same since several decades. Among these, the DISORT solver is still one of the most widely used. The DISORT code was developed 30 years ago, and while the code is maintained and updated regularly, the improvements are more geared towards new features than to a revision of the original setup. While the implementation was the best possible at the time, the memory constrains and language limitations of the time are nowadays considerably changed. On the other hand there is still the need of NRT retrievals, and the computing time of the multiple scattering needed in cloudy sky conditions is still the bottleneck of the FM calculation. Thus, we needed an improvement of the execution time of the DISORT algorithm. We modified the DISORT algorithm in three directions:
The modifications in the DISORT solver produce an improvement in calculation performances of a factor 3 with respect to the original version.
The FORUM instrument, selected for phase A of ESA Earth Explorer 9, samples the Earth atmosphere between 70 and 1600 cm-1 to investigate the Long Wave energy flux in FIR spectral region. The new version of DISORT solver has been used to model FORUM spectra, as well as limb sounding measurements in presence of clouds. Here we report the comparison of limb and FORUM spectra obtained with the two DISORT versions.
Implementation Of Three-Dimensional Box-Air-Mass-Factors In The LibRadtran Radiative Transfer Model
Schwaerzel, Marc (1,3); Emde, Claudia (2); Kuhlmann, Gerrit (1); Brunner, Dominik (1); Buchmann, Brigitte (1); Berne, Alexis (3) - 1: Empa, Swiss Federal Laboratories for Materials Science and Technology, Dübendorf, Switzerland; 2: LMU, Ludwig Maximillians University of Munich, Munich, Germany; 3: EPFL, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
The retrieval of vertical columns of trace gases such as NO2 and SO2 from satellites, aircraft or high-altitude platform stations (HAPS) requires air mass factors (AMF) to convert the fitted slant columns to vertical columns. AMFs can be calculated from vertically resolved AMFs (box-AMFs) with a radiative transfer model assuming horizontal homogeneity of surface reflectance, aerosols and trace gases.
However, the assumption of horizontal homogeneity is not necessarily valid where surface reflectance, aerosols and trace gases have a high spatial variability, for example, over cities. To study the effects of horizontal inhomogeneity on the AMFs and the retrieved trace gases, we implemented three-dimensional (3D) box-AMFs in the Mystic solver of the libRadtran radiative transfer model. The model output also provides the photon path-lengths in each box which is an intermediate result to calculate the box-AMFs and can be used for different scientific purposes (e.g. studies of impacts of aerosols on the incoming radiation). The implementation was tested by computing 3D box-AMFs for a spectrometer on an aircraft (6 km above surface), a high-altitude platform (20 km) and a satellite (700 km). We compared the size and shape of the effective footprint by varying instrument viewing direction, solar zenith angle, surface albedo and aerosol optical depth.
The preliminary results of 3D box-AMFs simulations show reasonable values. The new aspect of 3D box-AMFs compared to 1D box-AMFs is the possibility of observing the 3D structure of the box-AMFs and so to say the photons 3D path. This gives a much better appreciation of the possible influence of horizontal inhomogeneous input parameters. The photon paths can be investigated with input parameters variations. Preliminary results show a larger scattering of the photons with higher aerosol optical thickness or slant viewing direction of the instrument. Therewith, the boxes on the photons path from Sun to the instrument, after being reflected on the ground, have low AMFs values. Setting low albedo (<0.1) also seems to lower the AMFs values of these boxes and therefore suggests more important scattering.
In conclusion, 3D Box-AMFs implementation in Mystic allowed us to study the effects of changing input parameters on box-AMFs, in particular on their 3D shape and therefore to get sensitive to the possible influence of horizontal inhomogeneity on these box-AMFs.
Numerical and Experimental Studies for Monitoring Atmospheric Trace Gases using the newly developed SWING
Voicu, Octavian-Angelo (1,2); Iancu, Sebastian (1,2); Merlaud, Alexis (3); Calcan, Andreea (1); Constantin, Daniel (4) - 1: National Institute for Aerospace Research "Elie Carafoli" - INCAS, Romania; 2: Faculty of Physics, University of Bucharest, Romania; 3: Royal Belgian Institute for Space Aeronomy (BIRA-IASB), Belgium; 4: “Dunărea de Jos” University of Galați, Faculty of Sciences and Environment, Romania
Abstract: One of the most studied topics with respect to atmospheric pollution is the emission of trace gases. Recent developments in air borne remote sensing determinations of atmospheric constituents are based on UV/visible absorption measurements of scattered light at different elevation angles in addition to the traditional zenith-sky pointing. Thus, a newly instrument SWING (Small Whiskbroom Imager for atmospheric compositioN monitorinG), that employs on airborne MAX-DOAS (Multi AXis Differential Optical Absorption Spectroscopy) configuration, is used for data retrieval from an Unmanned Aerial Vehicle. Spectra recorded are being analyzed with the Differential Optical Absorption Spectroscopy (DOAS) method. This paper aims to determine the slant column densities (SCDs) and vertical column density (VCDs) of NO2 (Nitrogen Dioxide) and H2CO (Formaldehyde) during five days of measurements (10-14 September 2018) in a sub-urban area (Strejnicu, Romania). For this data spectra were recorded from a static position (at ground level with SWING mounted on a tripod) and at different altitudes with the instrument mounted on a UAV), the flights being performed in the morning and in the afternoon. These measurements contribute to the development of validation tools and expertise for air quality satellites in Romania.
Keywords: SWING, DOAS, atmospheric constituents, UAV platform.
Validation of TROPOMI NO2 and HCHO vertical columns with UV-Vis DOAS and FTIR instruments
Pinardi, Gaia (1); Vigouroux, Corinne (1); Langerock, Bavo (1); De Mazière, Martine (1); Granville, José (1); Compernolle, Steven (1); Lambert, Jean-Christopher (1); Hendrick, François (1); Van Roozendael, Michel (1); De Smedt, Isabelle (1); Eskes, Henk (2) - 1: BIRA-IASB, Belgium; 2: KNMI, The Netherlands
Within the S5P Validation Team, the NIDFORVal project (S5P NItrogen Dioxide and FORmaldehyde VALidation using NDACC and complementary FTIR and UV-Vis DOAS ground-based remote sensing data) aims at assessing the quality of nitrogen dioxide (NO2) and formaldehyde (HCHO) operational S5P products. Both Fourier Transform Infrared (FTIR) and UV-Visible Differential Optical Absorption Spectroscopy (UV-Vis DOAS) are recognized as independent techniques which can routinely provide total NO2 (DirectSun DOAS), tropospheric NO2 (Multi-AXis (MAX-) DOAS), and HCHO total column (FTIR and MAXDOAS) reference data sets for the long-term validation of satellite observations.
High-quality measurements from over 60 ground-based stations and 80 instruments will be gathered over the whole S5P mission timeline (10/2017-2023) from NDACC and other complementary networks, covering a large range of observation conditions including high, mid, and low latitudes, as well as remote, sub-urban, and urban polluted sites. About 50 stations were operational with data submission in rapid delivery mode during the commissioning and pre-operational phase and about 25 UV-vis DOAS stations were involved in the validation of the first TROPOMI total and tropospheric NO2 column operational products released last June. Data from 16 FTIR sites and 13 UV-vis stations were also used for the preliminary validation of the HCHO S5P vertical columns. The level of agreement varies from station to station, but globally and for both products, comparison results show negative biases (i.e. TROPOMI smaller than ground-based) which are within the accuracy requirements (50% for NO2 and 40-80% for HCHO).
Updates of NO2 and HCHO comparison results will be reported in this presentation, as well as the validation plan for the routine operations phase during which large TROPOMI data records will be accumulated.
Evaluation of a Discrete-wavelength DOAS-like NO2 Retrieval Approach for the High-Resolution Anthropogenic Pollution Imager (HAPI) Instrument Concept
Ruiz Villena, Cristina (1); Leigh, Roland (1); Monks, Paul (1); Parfitt, Claire E. (2); Vande Hey, Joshua (1) - 1: University of Leicester, United Kingdom; 2: Thales Alenia Space UK Ltd.
Outdoor air pollution is a major environmental health risk, particularly in urban areas. Nitrogen dioxide (NO2) is one of the primary air pollutants and is harmful to human health and ecosystems. NO2 monitoring is crucial for tackling the problem of air pollution and enforcing compliance with air quality regulations. This is done at a global scale using satellite instruments, which traditionally use the well-established Differential Optical Absorption Spectroscopy (DOAS) technique.
DOAS retrievals of NO2 are commonly done using high-resolution spectral information – usually hundreds of channels. This requires the use of complex hardware and provides limited spatial and temporal resolutions. Even recent developments struggle to resolve NO2 features at sub-urban scales and provide only one measurement per day at any given location.
In the work presented here a novel approach for NO2 retrievals in the visible range of the spectrum is evaluated for the advancement of the High-resolution Anthropogenic Pollution Imager (HAPI) instrument concept. One of the ways to reduce data volumes and increase spatial resolution is to reduce the amount of spectral information used in the retrieval (< 20 channels). Moreover, the use of fewer channels allows for simpler, cheaper instrument designs that could be deployed in constellations of small satellites, which in turn would allow for lower revisit times. The HAPI instrument concept, developed by the Air Quality group at the University of Leicester (UK), is based on these premises and thus has the potential to retrieve NO2 from space at unprecedented spatial and temporal resolution.
Discrete-wavelength DOAS retrievals are challenging due to NO2 being a weak absorber and the limited spectral information available. However, previous work using synthetic data suggests that they are possible provided there is a good signal-to-noise ratio. In the work presented here discrete-wavelength DOAS-like retrievals of NO2 are further evaluated using new synthetic data and real data from existing hyperspectral satellite instruments. Different instrumental and retrieval parameters and algorithms are considered. A sensitivity analysis of the retrieval results is conducted with the aim of finding the optimal configuration for the HAPI instrument concept.
Comprehensive Quality Assessment of recent Climate Data Records for ECVs NO2, HCHO and CO
Compernolle, Steven (1); Verhoelst, Tijl (1); Pinardi, Gaia (1); Granville, José (1); Hubert, Daan (1); Keppens, Arno (1); Niemeijer, Sander (2); Rino, Bruno (2); Beirle, Steffen (3); Boersma, Folkert (4); Clerbaux, Cathy (5); Coheur, Pierre (6); De Smedt, Isabelle (1); De Mazière, Martine (1); Eskes, Henk (4); George, Maya (5); Hendrick, François (1); Langerock, Bavo (1); Lorente, Alba (7); Peters, Enno (8); Richter, Andreas (8); Van Roozendael, Michel (1); van Geffen, Jos (4); Wagner, Thomas (3); Yu, Huan (1); Lambert, Jean-Christopher (1) - 1: Royal Belgian Institute for Space Aeronomy (BIRA-IASB), Brussels, Belgium; 2: s[&]t Corporation, Delft, The Netherlands; 3: Max Planck Institute for Chemistry (MPIC), Mainz, Germany; 4: Royal Netherlands Meteorological Institute (KNMI), De Bilt, The Netherlands; 5: LATMOS/IPSL, UPMC Univ. Paris 06, UVSQ, CNRS, Paris, France; 6: Spectroscopie de l’Atmosphère, Chimie Quantique et Photophysique, Université Libre de Bruxelles (ULB), Brussels, Belgium; 7: Wageningen University, Meteorology and Air Quality Group (WUR), Wageningen, The Netherlands; 8: Institute of Environmental Physics, University of Bremen (IUP-B), Bremen, Germany
Atmospheric nitrogen dioxide (NO2), formaldehyde (HCHO) and carbon monoxide (CO) play a key role as precursors to several Essential Climate Variables (ECVs) as well as in air quality. In the framework of the European Commission EO programme Copernicus, Climate Data Records (CDRs), established from satellite measurements, are collected and distributed among a wide set of users through the Copernicus Climate Change Service (C3S) coordinated by ECMWF. Here we report on a comprehensive quality assessment of three ECV-precursor CDRs generated in the H2020 QA4ECV project by KNMI, BIRA-IASB and ULB, respectively: QA4ECV NO2 from OMI, QA4ECV HCHO from OMI, and IASI-A FORLI CO. First results from S5P TROPOMI are also considered.
The quality assessment of the satellite CDRs is performed with the Multi-TASTE versatile validation system developed at BIRA-IASB, recently enhanced with updates from the FP7 QA4ECV and H2020 GAIA-CLIM projects. Its backbone is a generic validation protocol, virtually applicable to all atmospheric ECVs, that builds on the heritage of several BELSPO/PRODEX, EC, ESA and EUMETSAT projects. This protocol outputs a wide range of quality indicators enabling potential users to verify the fitness of the data records for their own purpose. The QA/validation protocol is currently implemented in two validation servers, both accessible online: (i) the QA4ECV-AVS (the QA4ECV Atmospheric ECV Validation Server), and (ii) the MPC-VDAF-AVS (the automated Validation Data Analysis Facility in charge of Sentinel-5p Mission Performance Centre routine validation).
The study relies on reference measurements acquired by ground-based DOAS and FTIR instruments at several sites of the Network for the Detection of Atmospheric Composition Change (NDACC). Interpretation of the data comparisons is not straightforward due to the interference of satellite data errors, reference measurement errors, and comparison errors caused by differences in temporal/spatial/vertical sampling and smoothing of natural variability. Therefore, a comprehensive uncertainty budget is established, coupling the detailed ex-ante uncertainty components provided with the satellite and ground-based data products to estimates of the co-location mismatch errors. The latter are assessed using the model-based OSSSMOSE observation system simulator, and also with empirical data-driven methods.
Significant negative biases and occasionally high comparison spreads are found in the direct comparison of OMI QA4ECV tropospheric NO2 columns with MAXDOAS data, the amplitude of which depends on season and on measurement site. Using the uncertainty budgeting approach described above, we try to attribute the observed discrepancies to a combination of comparison errors (co-location and resolution mismatch) and errors in satellite and/or reference measurement. For the so-derived measurement errors, we verify whether these are compatible with the reported ex-ante uncertainties.
Test Data Set (TDS) Generation for Verification of Sentinel-4 Level 2 Product Algorithms
Pukite, Janis; Beirle, Steffen; Wagner, Thomas - Max Planck Institute for Chemistry, Germany
The Sentinel-4 mission will be the first geostationary mission using an instrument with a large spectral coverage and moderate spectral resolution in UV-VIS-NIR spectral range for atmospheric composition monitoring on an hourly basis. While the algorithms for the L2 retrievals can build on heritage from previous missions (GOME-1/2, SCIAMACHY, OMI, and Sentinel-5P), the simulation and interpretation of the atmospheric radiative transfer is different compared to previous (polar orbiting) missions in many aspects. The challenges include e.g. limited spatial coverage, varying solar illumination during the day, effects of the BRF, varying stratospheric ozone absorption during the day, and varying cloud and aerosol scattering properties.
Herein we present the test data set (TDS) generated for the verification of the Sentinel-4 level-2 atmospheric monitoring products. In contrast to the previous missions (e.g. Sentinel-5P) that can use real data from similar polar-orbiting missions, the test data sets (TDS) for Sentinel-4 is obtained by synthetic radiative transfer simulations. In particular, RTM SCIATRAN is utilized, variability in atmospheric absorbers is prescribed by CTMs LOTOS-EUROS and TM5, and variable cloud and aerosol scenes are considered. In this way we comprehensively cover the new and specific observation geometries of Sentinel-4.
Development of Sentinel-4 Instrument Data Simulator
Hao, Nan; Gimeno Garcia, Sebastian - EUMETSAT, Germany
The Sentinel-4 (S4) mission, the first imaging spectrometer instrument to be flown on Meteosat Third Generation Sounding (MTG-S) satellite in geostationary orbit, will provide accurate data on an hourly basis of trace gases and aerosols over Europe and Northern Africa for climate, air quality, ozone and surface UV applications. It features bands in the ultraviolet (305-400 nm), and visible (400-500 nm) with a spectral resolution of 0.5 nm and in the near-infrared (750-775 nm) ranges with a spectral resolution of 0.12 nm.
To provide simulated S4-UVN instrument data, we are working to prepare the Instrument Data Simulator (IDS). IDS is supposed to provide test data for the L1b Processor and provide capability for instrument performance and calibration monitoring. The IDS consists of two main blocks: the Scene Generator (SG) simulates the radiance/irradiance at the entrance of the instrument and the Instrument Simulator (IS) simulates the response of the instrument on the input signal. The S4-UVN IS follows as much as possible the instrument forward model and will be developed using a ’travelling spectrum’ approach. In this approach, the flux in the instrument or signal and noise is modified step-by-step by a series of algorithms representing the effects of the different components of the instrument on signal when flowing through the instrument. The IDS architecture and instrument forward model will be introduced.
Towards Unified Error Reporting (TUNER)
von Clarmann, Thomas (1); Livesey, Nathaniel (2); Degenstein, Doug (3) - 1: KIT, Germany; 2: NASA Jet Propulsion Laboratory; 3: University of Saskatchewan, Institute of Space and Atmospheric Studies,
The Emerging SPARC Activity "Towards Unified Error Reporting (TUNER)" aims at unification and harmonization of error analysis and reporting of satellite measurements of atmospheric state variables. Its goal is to make error estimates of existing satellite observations of atmospheric temperature and constituent profiles intercomparable. The main tasks within this project are (a) to develop a coherent terminology and formalism adequate to represent all existing retrieval schemes; (b) to assess the completeness of error budgets provided by the instrument teams of the relevant space missions; (c) to find ways to provide estimates of error components not considered so far and diagnostic data not provided so far, and (d) to develop recommendations how retrieval errors and other diagnostic data can be communicated to the user without generating unnecessary data traffic. In this talk the progress made will be reported, difficulties encountered will be discussed, and future plans will be presented.
Continuous Ground-based Assessment of the Stability of ESA’s Ozone_cci and EC’s C3S O3 Column and Profile Climate Data Records
Verhoelst, Tijl (1); Hubert, Daan (1); Keppens, Arno (1); Granville, José (1); Van Roozendael, Michel (1); Lambert, Jean-Christopher (1); Balis, Dimitris (2); Garane, Katerina (2); Koukouli, MariLiza (2); Pazmino, Andrea (3); Goutail, Florence (3); Pommereau, Jean-Pierre (3); Delcloo, Andy (4); Kivi, Rigel (5); Stübi, René (6); Retscher, Christian (7); Zehner, Claus (7); Schepers, Dinand (8) - 1: BIRA-IASB, Brussels, Belgium; 2: AUTH, Thessaloniki, Greece; 3: LATMOS, Paris, France; 4: RMIB, Brussels, Belgium; 5: FMI, Sodankyla, Finland; 6: MeteoSwiss, Payerne, Switzerland; 7: ESA/ESRIN, Frascati, Italy; 8: ECMWF, Reading, UK
Atmospheric ozone plays a key role in the radiation budget of the Earth, both directly and through its chemical influence on other trace gases. Its corresponding importance in the context of climate change has led ESA and the European Commission to organize dedicated support for the development and provision of state-of-the-art ozone Climate Data Records (CDRs), more specifically in the context of the Climate Change Initiative (CCI) and of the Copernicus Climate Change Service (C3S) operated by ECMWF, respectively.
In view of the recent closure of Phase 2 of ESA’s Ozone_cci and the successful start of operational provision of the corresponding O3 CDRs to the Copernicus Climate Change Service (C3S 312a Lot 4), this contribution summarizes the ground-based validation of the O3 CDRs produced hitherto. These include CDRs of total column and vertical profile data (in nadir and limb mode) at level 2, level 3 and level 4, from a multitude of satellite platforms, retrieval systems, and merging schemes.
The validation of these climate-oriented data records is based on multi-decade time series of reference measurements collected from monitoring networks contributing to WMO’s Global Atmosphere Watch, such as GO3OS, NDACC and NASA’s SHADOZ. Acquired following Standard Operation Procedures (SOPs), the reference measurements are quality controlled and harmonized, and compared to the various satellite CDRs in BIRA-IASB’s Multi-TASTE validation system following the latest state-of-the-art protocols and tools. Our studies focus in particular on the long-term stability of the satellite data series, which may exhibit drifts and other long term patterns reflecting, e.g., instrumental drift and degradation, residual biases between different instruments, and changes in sampling of atmospheric variability and patterns.
The comparison results document the achieved quality of the CDR’s developed in Ozone_cci and provided to the C3S, in particular in terms of temporal stability. For instance, the level-3 and level-4 merged total O3 column products, covering up to four decades, are found to be stable w.r.t. the reference measurements at the 0.1%/decade level. Similarly, most nadir and limb profile CDRs achieve a level of stability consistent with that expected from instrument specifications. However, the requirements by climate users can be more stringent. More demanding targets may be reached with longer time series, the addition of new sensors and continued improvements in the data merging and trending schemes.
Several of these CDRs are therefore extended on a regular basis with additional observations (by e.g., GOME-2, IASI, OMI, OSIRIS, ACE-FTS and OMPS-LP). We describe how these operational streams of CDRs are validated accordingly in the context of the Copernicus Climate Change Service.
Operational Validation of S5P TROPOMI Total and Tropospheric Ozone data
Verhoelst, Tijl (1); Hubert, Daan (1); Lambert, Jean-Christopher (1); Langerock, Bavo (1); Compernolle, Steven (1); Keppens, Arno (1); Lerot, Christophe (1); Granville, José (1); Rasson, Olivier (1); Loyola, Diego (2); Heue, Klaus-Peter (2); Niemeijer, Sander (3); Rino, Bruno (3); Balis, Dimitris (4); Garane, Katerina (4); Koukouli, MariLiza (4); Pazmino, Andrea (5); Goutail, Florence (5); Pommereau, Jean-Pierre (5) - 1: BIRA-IASB, Brussels, Belgium; 2: DLR, Oberpfaffenhoffen, Germany; 3: s[&]t Corporation, Delft, The Netherlands; 4: AUTH, Thessaloniki, Greece; 5: LATMOS, Paris, France
Total and tropospheric columns of ozone are two key observables for the recently launched Sentinel-5 Precursor TROPOMI , which enhances to high resolution the long-term monitoring of ozone as a tropospheric pollutant, a dynamical tracer, a UV radiation shield and a climate forcing agent. The total column is derived from the radiance spectra both with a DOAS approach (the NRT product), and a direct fitting method (GODFIT algorithm, the OFFL product). Tropospheric column and upper tropospheric partial column data are derived from total column data at equatorial latitudes using, respectively, a convective cloud differential algorithm and a cloud slicing scheme.
The Validation Data Analysis Facility (VDAF) of the Sentinel-5p Mission Performance Centre (MPC) aims at providing a routine TROPOMI validation service to ESA, Level-2 data developers, Copernicus services and other data users. Supported jointly by ESA and Belspo/BIRA-IASB, it builds upon the heritage of two decades of geophysical validation applications for UV-Vis nadir-viewing instruments (GOME, SCIAMACHY, OMI, GOME-2) and on recent advances in Cal/Val practices and operational validation systems. The VDAF ingests correlative ground-based measurements, archived at ESA’s Validation Data Centre (EVDC) and collected from high-quality ground-based monitoring networks (GAW GO3OS, EARLINET, NDACC, TCCON...), and it compares them to TROPOMI data following community-endorsed protocols. After 9 months of commissioning, the VDAF system has now started routine operation.
In this contribution, we look in detail at the operational validation of the total and tropospheric O3 column products, covering both the near-real time (NRT) and offline (OFFL) data streams. The different sources of ground-based reference data are described, the criteria for co-location are motivated, and comparison results are presented for the different networks, including an analysis of dependences on key influence quantities and parameters such as latitude, solar zenith angle, cloud fraction, pixel size etc. These analyses reveal that the total O3 column products (both NRT and OFFL) satisfy the mission requirements, in systematic (<5%) as well as random (<2.5%) errors, with no apparent dependences on influence quantities. First results of the validation of the recently released tropospheric column products are also presented and assessed against mission requirements. Lessons learnt from this first phase of routine VDAF operation are discussed and potential improvements and extensions of the VDAF system are proposed.
Almost One Year Of TROPOMI/S5P Total Ozone Column Data: Global Ground-Based Validation
Koukouli, Maria Elissavet
Garane, Katerina (1); Balis, Dimitrios S. (1); Koukouli, Maria Elissavet (1); Bais, Alkiviadis (1); Lambert, Jean-Christopher (2); Verhoelst, Tijl (2); Granville, Jose (2); Pazmino, Andrea (3); Bazureau, Ariane (3); Goutail, Florence (3); Pommereau, Jean-Pierre (3); Fioletov, Vitali (4); McLinden, Chris (4); Heue, Klaus-Peter (5); Loyola, Diego (5); Xu, Jian (5); Zimmer, Walter (5); Romahn, Fabian (5); Lerot, Christophe (2); Van Roozendael, Michel (2); Zerefos, Christos (6) - 1: Aristotle University of Thessaloniki, Greece (AUTH); 2: Royal Belgian Institute for Space Aeronomy, Belgium (BIRA-IASB); 3: Laboratoire Atmosphères, Milieux, Observations Spatiales, France (LATMOS-CNRS); 4: Environment Climate Change, Canada; 5: Deutsches Zentrum für Luft- und Raumfahrt (DLR), Institut für Methodik der Fernerkundung (IMF), Germany; 6: Academy of Athens, Greece (AA)
Almost one year ago, in October 2017, the Sentinel 5 Precursor (S5P) mission was launched, carrying the Tropospheric Monitoring Instrument, TROPOMI. The new instrument provides a daily global coverage, has a swath width of 2600 km and covers bands in ultraviolet and visible (270–495 nm), near infrared (675–775 nm) and shortwave infrared (2305–2385 nm) at a spatial resolution as high as 7 km x 3.5 km. As such, TROPOMI extends the atmospheric composition record initiated with GOME/ERS-2 in 1996 and continued with the SCIAMACHY/ENVISAT, OMI/AURA and the two GOME-2/MetOp missions, until at least 2024, measuring atmospheric constituents including ozone, NO2, SO2, CO, CH4, HCHO and aerosol properties. The S5P mission is expected to bring up significant new components to the scientific knowledge of atmospheric processes, and it will have a significantly positive impact on the monitoring of the global atmospheric composition and the related sources and sinks.
Due to the ongoing need to understand and monitor the recovery of the ozone layer, as well as the evolution of the tropospheric pollution, total ozone will remain one of the leading species of interest during this mission as well. The Laboratory of Atmospheric Physics of the Aristotle University of Thessaloniki, Greece, is the co-ordinator of the TROPOMI’s Total Ozone Column Validation (VALTOZ) team and in this work we present the validation results of almost one year of TROPOMI NRT and offline data against ground-based quality-assured Brewer and Dobson total ozone column (TOC) measurements deposited in the World Ozone and Ultraviolet Radiation Data Center (WOUDC) and the European Brewer Network (EUBREWNET). Additionally, comparisons to Brewer measurements from the Canadian Network are performed, as well as to twilight zenith-sky measurements obtained with ZSL-DOAS (Zenith Scattered Light Differential Optical Absorption Spectroscopy) instruments, that form part of the SAOZ network (Système d'Analyse par Observation Zénitale) of the Network for the Detection of Atmospheric Composition Change (NDACC). Through the comparison of the TROPOMI measurements to the total ozone ground-based measurements from stations that are distributed globally, as the background truth, the dependence of the new instrument on latitude, cloud properties, solar zenith and viewing angles, among others, is examined and the results are presented and commented. Preliminary validation results show that the mean and the standard deviation of the percentage difference between TROPOMI and QA ground TOC is within 3.5 – 5% and 1.6 – 2.5 %, respectively, which are the limits set in the ESA’s official “Sentinel-5P Level 2 Product Requirements”.
ESA Fundamental Data Records for Atmospheric Composition (FDR4ATMOS)
Brizzi, Gabriele (1); Dehn, Angelika (2); Albani, Mirko (2) - 1: Serco Italia SpA, Italy; 2: ESA/ESRIN, Italy
The preservation and valorisation of Earth Observation (EO) data assets has gained importance in Space Agencies’ programs, alongside the development of new and innovative research missions. The Fundamental Data Record for Atmospheric Composition (FDR4ATMOS) project is part of the ESA Long Term Data Preservation (LTDP+) Programme aimed at the generation of long-term records of calibrated and quality-controlled EO data. Following the successful ERS-2 and ENVISAT mission operations and data exploitation, the FDR4ATMOS project shall revisit the long-standing series of historical satellite observations from the atmospheric composition sensors GOME, MIPAS and SCIAMACHY, and build long-term data records (Level 1) applying recalibration for the individual systems, but also inter-satellite calibration. The resulting decadal-scale EO-based data records will contribute improving the performance of the ESA historical data series and ensure continuity towards current and future missions. Fundamental Earth System Data Records enhance the potential of building the necessary base for reliable science applications, even climate monitoring, extending beyond the limits of the individual datasets and allowing the generation of products of augmented accuracy and length where a quantified evidence of the environmental variability over long periods of time, including climatic trends, can be detected. This paper aims at presenting the objectives of the ESA FDR4ATMOS project, expected to be issued as an ESA Invitation To Tender (ITT) at the end of 2018.
The Boundary-layer Air Quality-analysis Using Network of Instruments (BAQUNIN) Super Site for Satellite Cal/Val and Urban Environment Studies
Casadio, Stefano (1); Iannarelli, Anna Maria (1); Mevi, Gabriele (1); Cacciani, Marco (2); Siani, Anna Maria (2); Campanelli, Monica (3); Bassani, Cristiana (4); Cadau, Enrico (5); Goryl, Philippe (6) - 1: SERCO spa, Italy; 2: Physics Department, Sapienza University of Rome, Italy; 3: CNR-ISAC Rome, Italy; 4: CNR-IIA Monterotondo, Italy; 5: Sardegna Clima Onlus, Italy; 6: ESA/ESRIN, Italy
During the last four years the ESA Sensor Performance, Products and Algorithms (SPPA) section
invested significant resources in setting-up an atmospheric probing super-site in the area of Rome, named "Boundary-layer Air Quality-analysis Using Network of Instruments" (BAQUNIN) infrastructure. Atmospheric physics and remote sensing experts of Sapienza University, CNR-IIA and CNR-ISAC, who are in charge of hosting and operating the instrumentations at their premises,
are supported and coordinated by SERCO team for what concerns instrument maintenance, data analysis, and specific satellite Cal/Val needs.
In BAQUNIN, the ground based active and passive remote sensing instruments are operating in synergy, in both a urban context (University of Rome Sapienza), and in rural (CNR-IIA) and semi-rural (CNR-ISAC) environments. This instrumental set-up allows for the acquisition of qualitative and quantitative information for a wide range of atmospheric parameters such as trace gases and aerosols. The list of the BAQUNIN instrumentation comprises:
- LIDAR Raman+elastic+depolarisation (aerosols, H2O, clouds),
- SODAR (wind profiles in PBL)
- MFRSR radiometer (aerosols, O3 ,H2O),
- POM 01 L Prede sun-sky radiometer (aerosols, H2O, http://www.euroskyrad.net/)
- Brewer spectrophotometer (O3, SO2, NO2, http://www.eubrewnet.org/cost1207/)
- Pandora Spectrometers (O3, NO2, H2O, HCOH, SO2, aerosols, http://pandonia.net/)
- CIMEL photometer (aerosols, H2O, https://aeronet.gsfc.nasa.gov/new_web/index.html)
- YES broad-band UV radiometer
- All-sky camera (clouds, potentially aerosols)
- EM 27 FTIR Spectrometer (greenhouse gases)
- Meteo-station (air pressure, temperature and relative humidity)
The passive instruments are operated continuously, with the exception of the FTIR spectrometer,
only activated for short term campaigns, and of the LIDAR, which is operated on demand, typically
in correspondence of satellite overpasses (when close to nadir looking),
or in occurrence of particularly significant phenomena, such as Saharan dust events.
Geophysical products from all instruments are harmonised in terms of content (naming conventions, units), underpass a quality screening and are stored in NetCDF-CF format.
To complement the instrumental suite, the Weather Research and Forecasting (WRF) Model,
installed and running at ESRIN, is operated on a daily basis at very high spatial resolution (1km),
providing atmospheric dynamic forecasts for trajectory calculations and allowing
a more thorough analysis of the acquired BAQUNIN data.
The products acquired during BAQUNIN lifetime will be made available to the scientific community,
and will actively contribute to the validation of the aerosol and tropospheric trace gases satellite estimates produced by the Copernicus Sentinel-5p, Sentinel-4 and Sentinel-5, by EarthCare and Aeolus, and by the ESA Third Party Missions (TPM), such as the Ozone Monitoring Experiment (OMI).
In this contribution we describe in details the BAQUNIN set-up and data production/flow, along with recent S5p validation results.
Evolution Of The Esa Atmospheric Validation Data Center
Castracane, Paolo (1); Dehn, Angelika (2); Kiernan, Paul (3); Carty, Shane (3); Fjaeraa, Ann Mari (4); Boyd, Ian (5); McKinstry, Alastair (6) - 1: RHEA c/o ESA-ESRIN, Italy; 2: ESA/ESRIN; 3: Skytek; 4: NILU; 5: BC Scientific Consulting LLC; 6: ICHEC
The ESA Atmospheric Validation Data Centre (EVDC) serves as a central, long-term repository for archiving and exchange of correlative data for validation of atmospheric composition products from satellite platforms. The EVDC builds on the previous ENVISAT Cal/Val database system in operation at NILU since the early 2000s and provides tools for extraction, conversion and archival. The objective of the current ESA funded project lead by Skytek  with the partnership of NILU  and ICHEC , is to provide an online information system that supports users in managing and exploiting campaign datasets for Earth Observation missions and applications.
Through the web portal https://evdc.esa.int users can access to a large variety of data from campaigns, in-situ ground-based measurements, aircraft, balloons and, in general, from a wide range of stations and measurements principles for validation of the satellite atmospheric composition products. An important aspect for the Cal/Val data is the standardization of the format to enhance the usability of correlative data and ensure an extensive quality control. With this aim the portal offers numerous conversion tools and specific support for conversion to the GEOMS format .
EVDC provides, moreover, access to satellite Level-2 products for specific missions in particular Sentinel-5P and ADM-AEOLUS. Some new features and tools are available online via the EVDC portal e.g: the Orbit Predictor Overpass Tool (OPOT) and the Sub-Setting tool. The OPOT is based on the TLEs (Two-Line Element set)  and uses the Simplified General Perturbation Model (SGP4)  to predict and store their future orbits. Given a location or a region of interest (defined as a polygon) the OPOT produces a list of overpasses for that region and satellite for a future time range. The Sub-Setting facility uses the HARP toolkit  as its backbone. Users searching for Sentinel-5P data, can choose to perform a sub-setting operation on the file instead of downloading the entire file, moreover the data extraction can be scheduled specifying location(s), temporal window, distance from spatial reference through a systematic service which make the data package available once the service job is completed.
 Skytek http://www.skytek.com/; firstname.lastname@example.org
 NILU Norwegian Institute for Air Research. http://www.nilu.no/; email@example.com.
 ICHEC Irish Centre for High-End Computing. https://www.ichec.ie/
 GEOMS documentation: http://evdc.esa.int/documentation/geoms/
 Two Line Element set format: https://www.celestrak.com/NORAD/documentation/tle-fmt.php
 Models for Propagation of NORAD Element Sets. F. R. Hoots R. L. Roehrich 1980. https://www.celestrak.com/NORAD/documentation/spacetrk.pdf
 HARP documentation: https://cdn.rawgit.com/stcorp/harp/master/doc/html/index.html
ESA’s Campaign Database – an Opportunity for Atmospheric Science
Fehr, Thorsten; Schuettemeyer, Dirk; Casal, Tania; Davidson, Malcolm - ESA/ESTEC, Noordwijk, The Netherlands
In the framework of its Earth Observation Programmes the European Space Agency (ESA) carries out ground based and airborne campaigns to support geophysical algorithm developments, calibration/validation activities, simulation of future space-borne Earth Observation missions, as well as application developments related to atmosphere, land, oceans, solid Earth and cryosphere.
ESA has conducted over 150 airborne and ground based measurement campaigns in the last 37 years, of which more than 80 were carried out since 2005. During this period a number of campaigns have supported the preparation of ESA’s atmospheric satellite missions. While these campaigns aim to provide fundamental information to address specific topics related to technology or satellite developments, the resulting datasets are also made available to the atmospheric science community as a whole for research and development activities.
In recent years a number of campaigns have specifically addressed atmospheric dynamics and composition topics in preparation of the Aeolus and Sentinel-5 Precursor missions.
A series of campaigns have been supporting the development of the Aeolus Doppler Wind Lidar mission. Key for these activities is DLR’s A2D instrument, an airborne demonstrator for the ATLID satellite instrument on-board of the DLR Falcon aircraft. A2D is working with the same laser frequency and has a similar optical and electronic design as the space-borne instrument, which is ideal for supporting the development of the hardware, calibration procedures and retrieval algorithms. Already two campaigns have been completed: (1) The WindVal I was performed from Iceland in May 2015 as a joint ESA/DLR/NASA airborne campaign with a total of four airborne Doppler wind lidars. (2) WindVal II was conducted in September/October 2016 from Iceland with three research aircrafts and in the Mediterranean region. After the successful launch of Aeolus in August 2018, WindVal III is planned for November 2018, before in 2019 two calibration and validation campaigns over central Europe and Iceland, respectively, will be performed. An additional dedicated campaign in the tropics is planned for 2020 to specifically address the importance of Aeolus wind observations in this region.
In support of the development for new atmospheric composition instruments, ESA has carried out the Airborne ROmanian Measurements of Aerosols and Trace gases (AROMAT) campaigns. This series of campaigns was implemented in Romania in September 2014, August 2015 and June 2016. In addition, the AROMAPEX campaign was carried out in Berlin in April 2016. Main target species were NO2, SO2, formaldehyde and aerosols measured in urban and industrial environments with the aim to support the preparation and validation of the atmospheric composition missions such as Copernicus Sentinel-5 Precursor, Sentinel-4 and Sentinel-5. Dedicated Sentinel-5 Precursor validation campaign activities are currently prepared for summer 2019 and beyond, building on the experience AROMAT and additional national and international projects.
The WindVal, AROMAT and other atmospheric datasets together with their project descriptions are available from ESA’s Earth Observation Campaigns Data web site: https://earth.esa.int/campaigns. Future campaigns supporting ESA’s atmospheric mission will further enrich the campaign database providing scientist opportunities to enhance their research.
Data Fusion and Consistency of Fusing Data
Ceccherini, Simone (1); Carli, Bruno (1); Tirelli, Cecilia (1); Zoppetti, Nicola (1); Del Bianco, Samuele (1); Cortesi, Ugo (1); Kujanpää, Jukka (2); Dragani, Rossana (3) - 1: Istituto di Fisica Applicata “Nello Carrara” del Consiglio Nazionale delle Ricerche, Via Madonna del Piano 10, 50019 Sesto Fiorentino, Italy; 2: Finnish Meteorological Institute, Earth Observation Unit, P.O. Box 503, FI-00101 Helsinki, Finland; 3: European Centre for Medium-Range Weather Forecasts, Shinfield Park, Reading, RG2 9AX, United Kingdom
Many remote sensing observations of vertical profiles of atmospheric variables are obtained with instruments operating on space-borne and airborne platforms, as well as from ground-based stations. When the same portion (or nearby portions) of atmosphere is observed more times by the same instrument or by different instruments the measurements can be combined in order to obtain a single vertical profile of improved quality with respect to that of the profiles retrieved from the single measurements. Recently, a new method of data fusion, referred to as Complete Data Fusion (CDF), was proposed for use in the combination of independent measurements of the same profile. This is an a posteriori method that uses standard retrieval products and with simple implementation requirements provides products equivalent to those of the simultaneous retrieval, which is considered to be the most comprehensive way of exploiting different observations of the same quantity.
As part of the AURORA project, we have applied the CDF method to ozone profiles obtained from simulated measurements in the ultraviolet and in the thermal infrared in the framework of the Sentinel 4 mission of the Copernicus programme.
We observe that the quality of the fused products is very good when we fuse consistent profiles, instead the quality is degraded when we fuse profiles that are either retrieved on different vertical grids or referred to different true profiles.
In order to address this shortcoming, a generalization of the CDF method, which takes into account interpolation and coincidence errors, was developed. We determine the expressions of these errors and show how they enter in the CDF formula. This upgrade overcomes the encountered problems and provides products of good quality also when the fusing profiles are both retrieved on different vertical grids and referred to different true profiles. The approach developed to account for the interpolation and coincidence errors can also be followed to include other error components, such as forward model errors.
Complete Data Fusion of Multi-target Retrieval Products
Tirelli, Cecilia; Ceccherini, Simone; Carli, Bruno; Zoppetti, Nicola; Del Bianco, Samuele; Cortesi, Ugo - Institute of Applied Physics "Nello Carrara" (IFAC) CNR, Via Madonna del Piano 10, Sesto Fiorentino (FI), Italy
Observations of the Earth’s atmosphere for the vertical profiling of atmospheric variables are provided by many space-borne missions, airborne and ground-based campaigns, aiming at global and continuous measurements which can highlight trends in the atmospheric species and provide the input to the physical and chemical models that are used to predict the evolution of the atmospheric status. In the last two decades, there has been a strong focus on the development of innovative techniques to exploit all the available information from measurements of the same portion of the atmosphere to retrieve the best vertical profile estimate. In this framework, a new method of data fusion, referred to as Complete Data Fusion (CDF), was proposed as a-posteriori algorithm to combine independent measurements of the same profile into a single estimate for a comprehensive and concise description of the atmospheric state. This method uses standard retrieval products and requires a simple implementation.
Multi-target retrievals are frequently applied to the analysis of remote sensing observations to determine simultaneously atmospheric constituents reducing the systematic error caused by interfering species. It is thus crucial to adapt the CDF algorithm to fuse profiles obtained from multi-target retrievals, in order to extend its application to a greater number of remote sensing data.
In this work we present the results of the first application of the complete data fusion to multi-target retrieval products showing how the inputs of the CDF have to be modified to take into account that state vectors of the fusing measurements may contain only the same atmospheric variables or include different variables as well. We applied the method to simulated measurements in the thermal infrared and in the far infrared spectral ranges, considering the instrumental specifications and performances of IASI-NG and FORUM instruments, respectively.
The results obtained demonstrate that the CDF can deal with state vectors from multi-target retrievals both when they contain the same variables and when they have only a subset of variables in common, providing outputs of improved quality with respect to the input data.
Sentinel-5P/TROPOMI and S-NPP OMPS Data Support at GES DISC
Zeng, Jian (1); Vollmer, Bruce (2); Wei, Jennifer (2); Ostrenga, Dana (1); Johnson, James (1); Gerasimov, Irina (1) - 1: NASA GES DISC / Adnet Systems, Inc., United States of America; 2: NASA GES DISC, United States of America
The TROPspheric Monitoring Instrument (TROPOMI) on the Sentinel-5 Precursor (Sentinel-5P) is the first of the Atmospheric Composition Sentinels by the European Space Agency (ESA) that provides measurements of ozone, NO2, SO2, CH4, CO, formaldehyde, aerosols and cloud at high spatial, temporal and spectral resolutions. The early afternoon orbit of Sentinel-5P mission provides a strong synergy with the U.S. Suomi National Polar-orbiting Partnership (S-NPP) satellite, especially in that the S-NPP Ozone Monitoring and Profiling Suite (OMPS) facilitates high vertically resolved stratospheric and lower mesospheric ozone profiles.
The NASA Goddard Earth Sciences Data and Information Services Center (GES DISC) supports over a thousand data collections in the Focus Areas of Atmospheric Composition, Water & Energy Cycles, and Climate Variability and it is the Distributed Active Archive Center (DAAC) that is curating both offline Sentinel-5P TROPOMI and S-NPP OMPS Level-1B (L1B) and Level-2 (L2) products. Through its convenient and enhanced tools/services such as OPeNDAP and L2 Subsetting, GES DISC offers air quality remote sensing user communities facile solutions for complex Earth science data and applications.
This presentation will demonstrate TROPOMI and OMPS products including earthview radiance, solar irradiance, and currently available L2 datasets, as well as easy ways to access, visualize and subset data. The implementation of the End User License Agreement (EULA) between NASA GES DISC and all data users accessing data at GES DISC will be emphasized as well.
Agile Development of Atmosphere Science Products at the ICARE/AERIS Data and Services Center – Example of Data Processing and Services for CALIOP and Opportunities for the AEOLUS and EarthCare Missions.
Riedi, Jérôme; Pascal, Nicolas; Descloitres, Jacques; Neut, Sylvain; Focsa, Loredana; Vermeulen, Anne; Team, Icare - ICARE/AERIS, Université de Lille/CNRS, France
ICARE Data and Services Center has been estabished in 2005 to provide services to the science community and facilitate access to and utilization of satellites and ground-based observations of atmospheric aerosols and clouds properties, water cycle, and radiation. Its mission is to support research studies in atmospheric and climate sciences. ICARE is supported by the CNES and the Hauts-de-France Regional Council as part of a partnership with the University of Lille and the CNRS.
ICARE is one of the 4 data centers of AERIS, the French Atmospheric Data Infrastructure and contributes to numerous national and international collaborative projects (MACC, IAOOS, ORAURE, ROSEA, CaPPA, GEWEX, CHARMEX, ACTRIS, CCI, AEROCLUB, GAIA-CLIM, …).
ICARE partners with French and worldwide experts in the fields of atmospheric and climate sciences and with the international space agencies (CNES, NASA, ESA, EUMETSAT, ISRO, etc.). In particular, ICARE can support the development and exploitation of scientific ground segment for spaceborne missions related to atmospheric monitoring.
The main philosophy for development of science products at ICARE is to provide scientists and agencies with a flexible environment for implementation of science retrieval processors requiring minimal specifications while ensuring careful quality assessment and documentation of developped softwares and products. This relies partly on agile approach for interactions between scientists and ICARE development team and a robust and highly flexible production system that allows both massive reprocessing and near real time routine production for several on-going missions.
We will illustrate here the possibilities offered by ICARE/AERIS in terms of science products development and services through the example of the CALIPSO mission. Both standalone and synergistic CALIOP products developped within the A-Train mission will be illustrated. Potential opportunities for the support of Aeolus and EarthCARE missions will be discussed.
Atmospheric Mission Data Packaging - AMiDA
Natali, Stefano (1); Hirtl, Marcus (2); Triebnig, Gerhard (3); Aspetsberger, Michael (4); Cede, Alexander (5); Kreuter, Axel (6); Retscher, Christian (7) - 1: SISTEMA GmbH, Austria; 2: Zentralanstalt für Meteorologie und Geodynamik, Austria; 3: EOX IT Services GmbH, Austria; 4: Catalysts GmbH, Austria; 5: LuftBlick OG, Austria; 6: Innsbruck Medical University, Austria; 7: ESA ESRIN, Italy
The scientific and industrial communities are being confronted with a strong increase of Earth Observation (EO) satellite missions and related data. This is in particular the case for the Atmospheric Sciences communities, with the already launched Copernicus Sentinel-5 Precursor and the upcoming Sentinel-4, -5 and -3B, and ESA’s Earth Explorers scientific satellites ADM-Aeolus and EarthCARE. The challenge is not only to manage the large volume of data generated by each mission / sensor, to manage their variety. Tools are needed to be able to rapidly and trustfully identify, from all available datasets of a specific region for a specific timeframe, all available products for a selected field (e.g. Ozone, trace gases) and prepare these data into a format that is ready to be extracted and used /analysed (Analysis-Ready Data, ARD). Creating synergies among the different datasets will be key to exploit the full potential of the available information. In summary, there is a need of an “intelligent” packaging of subsets of the available data tailored to the users´ needs.
The scope of the “Atmospheric Mission Data Packaging” (AMiDA) project is to design, implement and demonstrate the functionalities of an infrastructure for access and distribution of a wide variety of EO data in the field of Atmospheric Sciences: heritage, current, and future missions will be managed by the platform, to allow the users accessing, visualizing and downloading a meaningful subset of this growing data stream.
The main AMiDA platform will be based on the existing TAMP platform (, ) that already allows accessing and manipulating a large variety of satellite, model and ground measurements data. The platform will be empowered with an effective spatial and temporal homogenization module and packaging module, that will allow creating, from heterogeneous data sources (e.g. SO2 total column data different satellites and numerical models) a single data structure (data cube) that will permit simultaneous exploitation of the various data sources. A product descriptor will be associated to the result keeping track of all original products and related metadata, processing parameters and results metadata. The resulting data cube can be exploited in platform (web application, Jupyter notebook) as well as being downloaded by the user.
A comprehensive demonstration campaign will be performed through five main use cases to demonstrate the capability of AMiDA to improve the usability of various satellite, model and ground measurement data.
Since the project is on its early stage, the scope of the contribution is to present the initiative and discuss with potential users their needs that can be successively integrated within the platform.
ESA Atmospheric Toolbox
Niemeijer, Sander (1); Fayt, Caroline (2); van Roozendael, Michel (2); Retscher, Christian (3) - 1: S[&]T, Netherlands, The; 2: BIRA-IASB, Belgium; 3: ESA/ESRIN, Frascati, Italy
The ESA Atmospheric Toolbox is one of the ESA Sentinel Toolboxes.
It consists of a set of software components to read, analyze, process and visualize a wide range of atmospheric data products. In addition to the Sentinel-5P mission it supports a wide range of other atmospheric data products, including those of previous ESA missions, ESA Third Party missions, Copernicus Atmosphere Monitoring Service (CAMS), ground based data, etc.
The toolbox consists of four main components that are called CODA, HARP, VISAN, and QDOAS
CODA provides interfaces for direct reading of data from earth observation data files. These interfaces consist of command line applications, libraries, direct interfaces to scientific applications (IDL and MATLAB), and direct interfaces to programming languages (C, Fortran, Python, and Java).
CODA provides a single interface to access data in a wide variety of data formats, including ASCII, binary, XML, netCDF, HDF4, HDF5, CDF, GRIB, RINEX, and SP3.
HARP is a toolkit for reading, processing and inter-comparing satellite remote sensing data, model data, in-situ data, and ground based remote sensing data.
The main goal of HARP is to provide easy access to data and to assist in the inter-comparison of datasets. By appropriately chaining calls to HARP command line tools one can pre-process datasets such that two datasets that need to be compared end up having the same temporal/spatial grid, same data format/structure, and same physical unit.
The toolkit comes with its own data format conventions, the HARP format, which is based on netCDF/HDF. Ingestion routines (based on CODA) allow conversion from a wide variety of atmospheric data products to this common format. In addition, the toolbox provides a wide range of operations to perform conversions on the data such as unit conversions, quantity conversions (e.g. number density to volume mixing ratios), regridding (including L2 to L3 gridding), vertical smoothing using averaging kernels, collocation of two datasets, etc.
VISAN is a cross-platform visualization and analysis application for atmospheric data and can be used to visualize and analyze the data that you retrieve using the CODA and HARP interfaces. The application uses the Python language as the means through which you provide commands to the application. The Python interfaces for CODA and HARP are included so you can directly ingest product data from within VISAN. Powerful visualization functionality for 2D plots and geographical plots in VISAN will allow you to directly visualize the ingested data.
QDOAS is a cross-platform application which performs DOAS retrievals of trace gases from spectral measurements (satellite, ground-based, mobile or aircraft-based instruments). This application already existed for many years but has recently been added to the toolbox as one of its components.
All components from the ESA Atmospheric Toolbox are Open Source and freely available.
Air Composition Services Based On Sentinel-5p Observations
Voors, Robert; de Vries, Johan; Ording, Barend; van der Meer, Arthur; van der Kooij, Matthijs - Airbus DS Netherlands, The Netherlands,
After the hardware and the testing phase and after delivering the fully calibrated TROPOMI instrument to ESA, Airbus DS in the Netherlands has started the development of air composition services that make use of the TROPOMI measurements. In this role of air composition information services provider we will play a pivotal role between current scientific development and commercial clients, where we make use of our instrument expertise as instrument prime for TROPOMI. We do this by maintaining close contact with numerous universities and institutes on the one hand and on the other hand, by developing relations with potential customers in order to better understand their needs. We have built mockups and demonstration models of the information services that we intend to provide in order to obtain direct feedback from the clients. In this paper we describe the status of the ongoing effort and we will highlight three specific cases. The three specific cases that we will describe in some details are  global monitoring service on atmospheric composition and emission allocation,  methane emission monitoring service (MEMS) and  Sulphur emission monitoring from ships. Air composition and meteorological data from satellites and local sensors are combined into a chemical transport model to build up or validate trace gas and particulate matter emission sources and their impact on air quality. The global monitoring service on atmospheric composition and emission allocation is using TROPOMI measurements to be able to quickly disclose new regions around the globe at low cost, as has been done for eastern Asia and the Indian continent. This yields a database of emission sources at a spatial resolution of about 3.5 km (and in the near future 1km) and provides daily observation data on regional and transboundary transport of pollutants. Target constituents are NO2, particulate matter, CH4, (tropospheric) ozone and SO2. For the methane emission monitoring service we are involved in a joint research project, which intends to develop methods for detection and quantification of localized CH4 emission sources. Key attention will be on gas leaks in the energy sector;other markets such as mining industry, agriculture and landfills will also be explored. For the Sulphur emission monitoring case TROPOMI measurements are expected to provide statistical information on potential offenders of current and future limits on the sulphur content in the exhaust. In this case, the TROPOMI data will be used as a stepping stone in the development of a service that will make use of more dedicated SO2 measurements.
08:30 - 10:20
AEROSAT/AEROCOM - Dialogue in the Satellite Aerosol Community and with Model Users
Popp, Thomas - DLR, Germany
Achievements of the ESA Aerosol_cci project
de Leeuw, Gerrit (2); Popp, Thomas (1); Pinnock, Simon (3) - 1: DLR, Germany; 2: FMI, Finland; 3: ESA/ESCAT, UK
In this paper we summarize the main achievements of the Aerosol_cci project within the ESA Climate Change Initiative (CCI) and discuss the future needs for
algorithm development (i. a. in the ESA CCI+ program). We also highlight the perspectives for routine dataset processing within the Copernicus Climate Change Service (C3S).
The main outcome of Aerosol_cci is as follows:
- substantial improvement of dataset quality
- consistent long-term records over 1-3 decades
- complementary parameters (Dust AOD, Fine Mode AOD, Total AOD, Absorbing AOD, stratospheric extinction) from different sensors AATSR, IASI, POLDER, MERIS, GOMOS
- demonstration of the information content for layer height (IASI), diurnal cycles (SEVIRI)
- establishment of a concept for pixel-level uncertainties
- establishment of AEROSAT as international forum
- integration and visibility of the European aerosol retrieval community
- evaluation of the usefulness of the datasets in 8 user case studies
- transfer of the routine tasks to C3S
- qualitative understanding of the reasons for differences between datasets processed with different algorithms (cloud masking, quality filtering – trade-off between accuracy and coverage)
- derivation of robust trends from different algorithms (with remaining biases)
Future algorithm work is needed for record extension (i. a. with Sentinel sensors), consolidation (e. g. propagation to gridded product uncertainties) and consistent integration of the various complementary datasets (e. g. ensembles, integrated products).
GRASP Aerosol and Surface Retrievals: Latest Application Results
Aspetsberger, Michael (1); Cobarzan, Petrut (1); Hangler, Andreas (1); Bindreiter, Lukas (1); Marth, Daniel (1); Wanzenböck, Moritz (1); Dubovik, Oleg (2); Lapyonok, Tatyana (2); Ducos, Fabrice (2); Fuertes, David (3); Litvinov, Pavel (3); Lopatin, Anton (3) - 1: Catalysts GmbH, Austria; 2: Laboratoire d’Optique Atmosphérique, CNRS, University of Lille 1, France; 3: GRASP-SAS, France
The GRASP (Generalized Retrieval of Aerosol and Surface Properties, Dubovik et al. 2011, 2014) algorithm is capable of deriving an extended set of aerosol and surface parameters including detailed particle size distribution, spectral refractive index, single scattering albedo and the fraction of non-spherical particles. Specifically, it uses the new multi-pixel concept - a simultaneous fitting of a large group of pixels with additional constraints limiting the time variability of surface properties and spatial variability of aerosol properties. This principle provides a possibility to improve the retrieval from multiple observations even if the observations are not exactly co-incident or co-located. All calculations are done on-line without using traditional look-up tables, with detailed aerosol and surface models and fully accounting for all multiple interactions of scattered solar light with aerosol, gases and the underlying surface.
We will present the latest results of the applications to Sentinel-5P/TROPOMI, Sentinel-3/OLCI, PARASOL/POLDER, ENVISAT/MERIS, TERRA/MISR, AQUA/MODIS, and the ongoing preparations for the Sentinel-4 mission. The lessons learned with each new mission has been consolidated into the GRASP Cloud. The wide range of applicability, from multi-angular polarimetric to single-view intensity only observations, from sun-synchronous to geostationary platforms, reflects the versatility of GRASP.
1. Dubovik, O., M. Herman, A. Holdak, T. Lapyonok, D. Tanré, J. L. Deuzé, F. Ducos, A. Sinyuk, and A. Lopatin, “Statistically optimized inversion algorithm for enhanced retrieval of aerosol properties from spectral multi-angle polarimetric satellite observations”, Atmos. Meas. Tech., 4, 975-1018, 2011.
2. Dubovik, O., T. Lapyonok, P. Litvinov, M. Herman, D. Fuertes, F. Ducos, A. Lopatin, A. Chaikovsky, B. Torres, Y. Derimian, X. Huang, M. Aspetsberger, and C. Federspiel “GRASP: a versatile algorithm for characterizing the atmosphere”, SPIE: Newsroom, DOI:10.1117/2.1201408.005558, Published Online: September 19, 2014. http://spie.org/x109993.xml.
Joint Retrieval of Aerosol Optical Depth and Surface Reflectance over Land Using Geostationary Satellite Data
Xue, Yong (1); Xie, Yanqing (2); Guang, Jie (2) - 1: University of Derby, United Kingdom; 2: RADI/CAS
Abstract — The Advanced Himawari Imager (AHI) aboard the Himawari-8 geostationary satellite provides high-frequency observations with broad coverage, multiple spectral channels, and high spatial resolution. In this study, AHI data were used to develop an algorithm for joint retrieval of aerosol optical depth (AOD) over land and land surface bidirectional reflectance. Instead of performing surface reflectance estimation before calculating AOD, the AOD and surface bidirectional reflectance were retrieved simultaneously using an optimal estimation method. The algorithm uses an atmospheric radiative transfer model coupled with a surface bidirectional reflectance factor (BRF) model. Based on the assumption that the surface bidirectional reflective properties are invariant during a short time period (i.e., a day), multiple temporal AHI observations were combined to calculate the AOD and surface BRF. The algorithm was tested over East Asia for year 2016, and the AOD retrieval results were validated against the AErosol RObotic NETwork (AERONET) sites observation and compared with the Moderate Resolution Imaging Spectroradiometer (MODIS) Collection 6.0 AOD product. The validation of the retrieved AOD with AERONET measurements using 14,713 colocation points in 2016 over East Asia shows a high correlation coefficient: R=0.88, RMSE=0.17, and approximately 69.9 % AOD retrieval results within the expected error of . A brief comparison between our retrieval and AOD product provided by Japan Meteorological Agency (JMA) is also presented. The comparison and validation demonstrates that the algorithm has the ability to estimate AOD with considerable accuracy over land.
Particle size distribution of stratospheric aerosols: from SCIAMACHY to ALTIUS
Rozanov, Alexei (1); Malinina, Elizaveta (1); Fussen, Didier (2); Burrows, John P. (1) - 1: University of Bremen, Germany; 2: INSTITUT D'AERONOMIE SPATIALE DE BELGIQUE, Brussels, Belgium
Stratospheric aerosols play an important role in the Earth system and in the climate. Through their scattering of solar radiation back to the space and by heating the stratosphere through the absorption of thermal infrared radiation upwelling from the troposphere for the case of strong aerosol loading, stratospheric aerosol directly impacts the radiative forcing and thus the energy balance of the Earth’s atmosphere. In addition, an indirect impact of stratospheric aerosols arises from providing a surface for heterogeneous chemical reactions, which release halogens and lead to the catalytic depletion of ozone. As the presence of the aerosol alters scattering properties of the atmosphere, a good knowledge of aerosol characteristics is also essential to achieve a high accuracy in the remote sensing of the atmospheric trace gases (e.g. ozone). In spite of the progress made since the discovery of the Junge layer, our current understanding of the sources and sinks of the stratospheric aerosols and our ability to predict how the stratospheric aerosol layer may be affected by future climate change, or how it impacts on climate change, are limited and not sufficient to meet the need of policymakers.
Valuable information to fill the gap in our knowledge is provided by the retrieval of global data sets of stratospheric aerosol particle size distribution parameters, gained from space borne passive remote sensing observations in the visible-NIR-SWIR spectral ranges. Recently, a data set of two parameters of the aerosol particle distribution (mode radius and distribution width) has been created at the University of Bremen using the measurements of the scattered solar light from Scanning Imaging Absorption Spectrometer for Atmospheric CHartographY (SCIAMACHY) instrument operated on board the European ENVISAT Satellite from August 2002 to April 2012. This data set has been used to investigate the seasonal and inter-annual variations in the stratospheric aerosol distributions and their response to the volcanic eruptions. The results of this study are summarized in this presentation.
As ENVISAT ceased its operation unexpected in 2012 and there is no European replacement, it is extremely important to look for alternative sources of information about stratospheric aerosols. Besides SAGE III/ISS instrument of NASA launched in 2017, only the ALTIUS instrument planned for launch in 2021 in the framework of the European Earth Watch Programme has a capability of providing information sufficient for a retrieval of two or more parameters of the stratospheric aerosol particle size distribution. As the measurements in the limb viewing geometry to be performed by ALTIUS and its wide spectral coverage (in particular NIR and SWIR ranges) are quite similar to those of SCIAMACHY, there is a high potential for a successful adaptation of the SCIAMACHY retrieval to ALTIUS. In the second part of this presentation we discuss the information potential of the measurements of the scattered solar light from ALTIUS with respect to the retrieval of the particle size distribution parameters of stratospheric aerosols.
Retrieval of Stratospheric Aerosol Particle Size Distribution from GOMOS using AerGOM
Bingen, Christine (1); Robert, Charles (1); Brühl, Christoph (2); Schallock, Jennifer (2); Vanhellemont, Filip (1); Mateshvili, Nina (1); Dekemper, Emmanuel (1); Fussen, Didier (1) - 1: BIRA-IASB, Brussels, Belgium; 2: Max-Planck Institute for Chemistry, Mainz, Germany
The retrieval of the particle size distribution of stratospheric aerosols, along with their derived microphysical and radiative properties remains an important challenge, as size information is of particular importance to characterize stratospheric aerosols and to understand their impact on climate.
In this work, we retrieve particle size information using data from GOMOS. The retrieval of the particle size distribution is based on the aerosol extinction coefficients at a set of wavelengths between 350 and 750nm provided by the AerGOM algorithm, which is optimized for the retrieval of aerosol properties.
While it is particularly efficient to provide a high measurement rate, the use of stars as light sources however implies a limited signal-to-noise ratio. Therefore, strategies have to be implemented to alleviate the impact of the varying and star-dependent measurement quality on the retrieval of extinction, and beyond that, on the additional inversion of extinction needed to retrieve the aerosol size parameters.
In this presentation, we’ll give the latest results of our work on the particle size distribution retrieval, and present the methodology used to derive size information. We’ll show our first time series (2002-2012) obtained for several size parameters and derived quantities, and a first evaluation of our dataset against results of simulations by the chemistry-climate model EMAC. In this respect, we will analyse the size information provided by GOMOS using EMAC time series of the contribution of the different modes (Aitken mode versus accumulation mode; simulation of volcanic and dust events) as diagnostic tools.
Characterization of Aerosol and Clouds in the Upper Troposphere and Lower Stratosphere using Infrared Limb Emission Measurements
Griessbach, Sabine (1); Dinelli, Bianca Maria (2); Gerber, Daniel (3); Höpfner, Michael (4); Hoffmann, Lars (1); Kahnert, Michael (5); Krämer, Martina (1); Maestri, Tiziano (6); Siddans, Richard (3); Spang, Reinhold (1); Ungermann, Jörn (1); Wu, Xue (7) - 1: Forschungszentrum Jülich GmbH, Germany; 2: ISAC-CNR, National Research Council of Italy, Bologna, Italy; 3: RSG, Rutherford Appleton Laboratory, Didcot, UK; 4: IMK-ASF, Karlsruhe Institute of Technology, Karlsruhe, Germany; 5: Swedish Meteorological and Hydrological Institute, Norrköping, Sweden; 6: DIFA, University of Bologna, Bologna, Italy; 7: Forschungszentrum Jülich GmbH, Germany; LAGEO IAP, Chinese Academy of Sciences, Beijing, China
The aim of the ESA study "Characterisation of particulates in the UTLS" was to investigate the cloud and aerosol measurement capabilities of a potential infrared limb sounding (IRLS) instrument. Therefore, we examined advanced available particle measurement techniques for MIPAS/Envisat and transferred them to the IRLS instrument specifications.
The investigated IRLS instrument has a coarser spectral resolution, but a higher spatial resolution than MIPAS. Despite the reduced spectral resolution we could show that the MIPAS detection methods are transferable to IRLS with a comparable sensitivity. For the IRLS the spatial information, e.g. cloud top height, was improved. Moreover, for cirrus clouds we demonstrated that the better spatial resolution of IRLS measurements allows for 3D retrievals of clouds. The comparison of the detection sensitivities and coverage with those of established instruments (e.g. SAGE II, CALIOP, OSIRIS, GOMOS) showed that infrared limb emission instruments can provide global information on a daily basis and hence, can fill measurement gaps in the horizontal and vertical coverage e.g. at high latitudes and in the UTLS, and in detection sensitivity e.g for sulfate aerosol.
The wealth of spectral information provided by infrared limb emission measurements allows for the retrieval of microphysical properties, e.g cloud/aerosol type, particle size, and extinction. For small ice cloud particles, a particle size distribution retrieval was demonstrated. For polar stratospheric clouds (PSC) the PSC type classification algorithm was demonstrated and the microphysical retrieval was advanced. For the aerosol detection the performance of the ice cloud filter was assessed, it was demonstrated that a reliable classification between volcanic ash and sulfate is feasible, and a retrieval scheme (radius, number, extinction) was developed.
For ice clouds, PSCs, and volcanic aerosol we found all MIPAS aerosol and cloud retrieval methods to be transferable to the IRLS and achieving a comparable or better sensitivity. Moreover, the spatial detection capabilities were significantly improved for the IRLS. From the transferability of the methods to the IRLS we conclude that they also will be applicable to existing infrared limb emission instruments, such as GLORIA, past instruments, such as CRISTA, and future instruments, such as ATMOSAT.
10:50 - 12:35
Quantifying the Impact of Volcanic and Industrial Emissions on Clouds
Povey, Adam Charles (1); Christensen, Matt W (2); McGarragh, Greg R (3); Thomas, Gareth E (4); Poulsen, Caroline R (4); Proud, Simon R (2); Grainger, Roy G (1) - 1: NCEO, University of Oxford, United Kingdom; 2: AOPP, University of Oxford, United Kingdom; 3: Cooperative Institute for Research in the Atmosphere, CO, USA; 4: RAL Space, harwell, United Kingdom
One of the greater uncertainties in climate observation and modelling is the means by which aerosols interact with clouds. Many mechanisms have been observed and theorised, producing both positive and negative radiative effects. However, the relative real-world importance of these is unclear, which complicates the parametrization of cloud processes within models. This presentation will outline a technique to quantify the variation of cloud micro- and macro-physical properties as a function of aerosol loading.
Satellite observations of localised aerosol sources, such as industrial areas or volcanoes, are used as a natural laboratory where fresh aerosols are injected into an otherwise homogeneous field. Perturbed and pristine conditions can be separated by aligning the retrievals with the local wind vector. Approximately 100 sites around the globe, covering a range of anthropogenic and natural aerosol sources, were analysed. The first indirect aerosol effect is clearly observed, with weaker evidence for cloud invigoration. Liquid water path effects are observed in some circumstances.
Operational Cloud Products In The UV-VIS-NIR: From Sentinel-5 Precursor Towards Sentinel-4 And Sentinel-5
Lutz, Ronny (1); Argyrouli, Athina (2,1); Romahn, Fabian (1); Loyola, Diego (1) - 1: German Aerospace Center (DLR), Remote Sensing Technology Institute; 2: Technical University of Munich (TUM), Department of Civil, Geo and Environmental Engineering
The Copernicus missions focused on atmospheric composition and trace gas retrieval operate in the UV/VIS/NIR/SWIR spectral region.
For an accurate trace gas retrieval, also a precise knowledge of the cloud properties in this wavelength region at each given scene is required.
In this work we present the algorithms for retrieving the operational cloud products from the low earth orbit (LEO) Sentinel-5 Precursor and Sentinel-5 missions and the geostationary (GEO) Sentinel-4 mission.
The cloud retrieval algorithms OCRA (Optical Cloud Recognition Algorithm) and ROCINN (Retrieval of Cloud Information using Neural Networks) have their heritage with GOME/ERS-2 and GOME-2 MetOp-A/B, where they have already been successfully implemented in an operational environment.
The ROCINN algorithm retrieves cloud height, cloud optical thickness and cloud albedo from NIR measurements in and around the oxygen A-band, taking as input the cloud fraction computed with the OCRA algorithm that is based on a broad-band UV/VIS/NIR color space approach.
This OCRA color space approach makes use of the assumption that clouds usually have a higher reflectivity than the surrounding surface and that the cloud reflectivity is almost wavelength independent across the UV/VIS/NIR region.
Assigning R, G and B colors to respective broad-band reflectances in the NIR, VIS and UV leads to clouds appearing white in the normalized RGB color space. The scene furthest away from the white point is the one where we expect the least possible amount of cloud contamination.
Joining all these scenes on a global grid allows to generate a cloud-free reflectance background composite map which, together with the measured reflectance, can be used to calculate a radiometric cloud fraction for any given measurement.
The cloud height, optical thickness and albedo retrieved by ROCINN are provided for two different cloud models. One which treats clouds more realistically as layers of scattering water droplets (clouds-as-layers, CAL) and one which treats clouds as simple Lambertian reflectors (clouds-as-reflecting boundaries, CRB).
Initial comparisons and validation results are shown for Sentinel-5P and perspectives are outlined for Sentinel-4.
Aerosol Mnitoring Over Vipava Valley Using Raman Polarization Lidar
Wang, Longlong (1); Stanič, Samo (1); Bergant, Klemen (1,2); Eichinger, William (3); Gregorič, Asta (1,4); Močnik, Griša (5); Drinovec, Luka (5) - 1: University of Nova Gorica, Slovenia; 2: Slovenian Environment Agency, Ljubljana, Slovenia; 3: The University of Iowa , Iowa City, IA, United States; 4: Aerosol d.o.o., Ljubljana, Slovenia; 5: Jožef Stefan Institute, Ljubljana, Slovenia
Vipava valley in southwest Slovenia is a representative hot-spot for complex mixtures of different aerosol types of both anthropogenic and natural origin in mountainous terrain. An investigation of aerosol properties throughout the troposphere in different atmospheric conditions was made possible by a deployment of a two-wavelength polarization Raman lidar system combining with in-situ measurements in the valley (in the town of Ajdovščina) from September 2017. Using its aerosol identification capabilities, which are based on particle depolarization ratio and lidar ratio measurements, it was possible to identify predominant aerosol types in the observed atmospheric structures, for example in different atmospheric layers in the case of the stratified atmosphere. Primary anthropogenic aerosols within the valley were found to be mainly emitted from two sources: individual domestic heating systems, which mostly use biomass fuel, and from traffic. A considerable fraction of natural aerosols (for example mineral dust and sea salt), transported over large distances, were observed both above and entering into the planetary boundary layer. According to the properties of different aerosol types, backscatter contribution of each aerosol type was evaluated and the corresponding extinction contribution was derived from lidar observations. Statistical analysis of the presence of different aerosol types was performed on the entire available dataset from 2017 and 2018.
Enhancing The KNMI Aerosol Layer Height Algorithm's Computational Speed: A Use Case Of Machine Learning For Substituting Line By Line Radiative Transfer Models
Nanda, Swadhin (1,2); Veefkind, Pepijn (1,2); de Graaf, Martin (1) - 1: KNMI (Royal Netherlands Meteorological Institute), The Netherlands; 2: Department of Geoscience and Remote Sensing, Delft University of Technology, The Netherlands
The KNMI aerosol layer height algorithm is planned to be installed into the Level-2 processors of the Sentinel-4/5 missions and is already operationally processing Sentinel-5P/TROPOMI spectra. Currently, the algorithm uses a forward model that computes top of atmosphere reflectance and its derivatives using line-by-line radiative transfer calculations for the oxygen A-band. In total of 3980 calculations per iteration in the optimal estimation retrieval framework have to be done. Depending on the operational hardware, these calculations can take up to 60 seconds per iteration per pixel, with a minimum of 3 iterations for convergence (over the ocean). Due to this, the near real time and the offline aerosol layer height product is severely hindered in its output capacity.
Another significant issue with retrieving aerosol layer height in the near infrared region is the brightness of vegetated surface, which makes land much brighter and consequently reduces the signal aerosols contribute to the top of atmosphere reflectance. As a result, retrievals over land are less reliable than over land, where the background scene is dark enough to allow aerosol signals to be interpreted by the retrieval algorithm unhindered. The Level-2 processor suffers from wasting valuable computational time retrieving inaccurate aerosol layer height values over land.
There are two problems to solve here: a) improve the algorithm's performance over land, thereby improving the computational efficiency of the algorithm, and b) improve the algorithm's speed per iteration. In this presentation, two methods are introduced in order to overcome these issues:
1. The dynamic scaling method has been designed to force the optimal estimation framework to refocus the retrieval algorithm's attention away from surface photon contribution to the aerosol contribution in the top of atmosphere reflectance. This method is a simple augmentation of the existing KNMI aerosol layer height retrieval framework, requiring very simple changes to the code.
2. The line-by-line calculations of the top of atmosphere reflectance and its derivative with respect to model parameters has been replaced by neural networks. This reduces the number of calculations per iteration from 3980 to less than 5 per iteration, thereby significantly improving the algorithm's speed. This method can calculate forward model outputs in a vectorised fashion, computing 100,000 forward model calculations in 12 seconds.
This oral presentation highlights the recent breakthroughs in the aerosol layer height algorithm, which will cement it to be an operational success in the near future.
The Updated Mineral Aerosols Profiling From Infrared Radiances (MAPIR) Retrieval Algorithm: Dust 3D Retrievals From IASI
Callewaert, Sieglinde; Vandenbussche, Sophie; De Mazière, Martine - BIRA-IASB, Belgium
Windblown desert dust is the most prominent type of aerosol in the low troposphere. It affects the radiation directly through absorption, scattering and emission of light, and indirectly, through interactions with clouds. All radiative effects of dust depend on the horizontal and vertical distribution of that aerosol in the troposphere. The dust vertical distribution is not yet well characterized, at least not enough to allow studying the interactions between dust and clouds or the effect on atmospheric circulation.
The Royal Belgian Institute for Space Aeronomy (BIRA-IASB) has developed a strategy to retrieve dust aerosol vertical profiles from thermal infrared radiances measured by the IASI instrument onboard the Metop satellite series (Vandenbussche et al., 2013). This strategy, based on the optimal estimation formalism, is entitled Mineral Aerosol Profiling from Infrared Radiances (MAPIR) and has been used under ESA’s Climate Change Initiative aerosols project to produce 9 years of dust 3D distributions (Popp et al, 2016). The validation has shown an AOD overestimation but a good mean aerosol altitude (Kylling et al., 2017). Over desert surfaces with low emissivity, there were however frequently convergence issues with MAPIR v3, which lead to a loss of valuable data.
To cope with those weaknesses and to make the processing less costly, current research lead to an updated strategy, MAPIR v4. The algorithm is improved by replacing the radiative transfer code from Lidort (Spurr et al. 2008) to RTTOV (ECMWF NWPSAF) and by making some structural changes in the retrieval method. The better convergence was mainly achieved by implementing the Levenberg-Marquardt modification to the Gauss-Newton iteration technique (Rodgers, 2000). A new dataset of 11 years of dust 3D distributions is currently produced with MAPIR v4 and will be presented. This data set will become available through the Copernicus Climate Change Services.
In this talk, we will describe the updated algorithm, show results of the reprocessing and compare them with Aeronet and CALIOP measurements.
The Composition Of The Asian Monsoon Upper Troposphere: A Synergy Of Satellite And Airborne Remote Sounding
Höpfner, Michael (1); Ungermann, Jörn (2); Spang, Reihnold (2); Johansson, Sören (1); Friedl-Vallon, Felix (1); Orphal, Johannes (1); Riese, Martin (2); Stiller, Gabriele (1); Stroh, Fred (2); Bucci, Silvia (3); Legras, Bernard (3); Wohltmann, Ingo (4) - 1: Institute of Meteorology and Climate Research, Karlsruhe Institute of Technology, Karlsruhe, Germany; 2: Institute of Energy and Climate Research, Stratosphere, Forschungszentrum Jülich, Jülich, Germany; 3: Laboratoire de Météorologie Dynamique, UMR8539, IPSL, UPMC/ENS/CNRS/Ecole Polytechnique, Paris, France; 4: Alfred Wegener Institute for Polar and Marine Research, Potsdam, Germany
Strong convection within the Asian monsoon system quickly transports polluted air masses from the boundary layer into the upper troposphere. The physical and chemical processes within this different environment and the fate of the air is subject of current research. The main sources of altitude-resolved observational data from this region stem from satellite limb and lidar observations, like MIPAS on Envisat, CRISTA on SPAS, MLS on Aura, ACE-FTS on SCISAT, and CALIOP on CALIPSO. StratoClim, the first high-altitude aircraft field campaign in the core of the Asian monsoon, took place from Kathmandu, Nepal, in July and August 2017. During this campaign, we operated the GLORIA (Gimballed Limb Observer for Radiance Imaging of the Atmosphere) infrared limb-imaging spectrometer on board the Geophysica airplane. Two-dimensional cross-sections of various trace gases (e.g. ozone, water vapour, nitric acid, PAN, ethane, ammonia) and aerosol information along the flight paths over Nepal and India have been retrieved from the limb spectra covering an altitude range between about 10 and 20 km with spatial resolutions of 0.5-1 km vertically and 3 km horizontally along track. We analyse this airborne dataset with the help of temporally and locally connected satellite data of nadir-pointing instruments like IASI, to infer the underlying composition in the lower and middle troposphere, and geostationary satellites to deduce the presence of convective influence. Further, the GLORIA observations will be linked to the global context and temporal development by utilizing measurements of limb-sounders like CRISTA and MIPAS.
New Reflectance Background Maps for the Accurate Retrieval of MICRU Effective Cloud Fractions in the UV/Vis Wavelength Region
Sihler, Holger (1); Richter, Andreas (2); Beirle, Steffen (1); Hörmann, Christoph (1,3); Gutenstein-Penning de Vries, Marloes (1,4); Wagner, Thomas (1) - 1: Max Planck Institute for Chemistry, Germany; 2: Institute of Environmental Physics, University of Bremen, Bremen, Germany; 3: now at: Volume Graphics GmbH, Heidelberg, Germany; 4: now at: Deutscher Wetterdienst, Offenbach, Germany
The accuracy of satellite retrievals of tropospheric trace gases (e.g., NO2, HCHO) strongly depends on the accuracy of the corresponding cloud fraction, particularly for small cloud fractions. The main goal of the newly developed MICRU (Mainz Iterative Cloud Retrieval Utilities) algorithm is, therefore, to improve the accuracy of small cloud fractions by improving the retrieval of background reflectance maps. The approach is applicable to various UV/vis satellite cloud retrievals.
The most important feature of our approach is the derivation of the minimum reflectance map for a certain satellite sensor and wavelength range from the measurements themselves. A particular advantage of our algorithm is that it integrates measurements of the entire instrument swath. The algorithm builds on the assumption that the surface is dark compared to clouds. Therefore, it is limited to regions not permanently covered by clouds, ice or snow. The algorithm transforms measured reflectances to Lambertian Equivalent Reflectances (LER), thereby removing the viewing-angle dependent contribution of Rayleigh scattering, yet minimum LER values are found to significantly depend on viewing zenith angle (VZA), time, scattering angle, and reflection angle - mainly due to systematic effects like instrument degradation and surface BRDF effects. Therefore, our approach features a minimum LER parametrised by time, VZA, scattering angle, and reflection angle. The comparison between different MICRU channels suggests that the resulting mean standard error of small effective cloud fractions (CF<20%) retrieved in the wavelength range between 375 and 757nm is smaller than 4%. Moreover, cloud fractions retrieved using different instrument channels are consistent over the entire swath.
In this presentation, reflectance background maps and effective cloud fractions are derived from radiance measurements by GOME-2A between 2007 and 2013. Mean cloud fractions are discussed as well as systematic differences to two operational products of the effective cloud fraction: FRESCO and OCRA. Systematic differences (VZA dependence, coast contrasts, biases) between all three algorithms are investigated. Finally, the potential of applying MICRU effective cloud fractions for the retrieval of nitrogen dioxide (NO2) is illustrated based on the QA4ECV data set.
14:05 - 15:50
The Diurnal Cycles of Cloud Profiles and Water Vapor over Land and Ocean seen by the CATS Spaceborne Lidar and Megha-Tropiques Sensors
Noel, Vincent (1); Chepfer, Helene (2); Chiriaco, Marjolaine (3); Brogniez, Helene (3); Yorks, John (4); Raberanto, Patrick (5) - 1: Laboratoire d'Aérologie, CNRS, France; 2: Laboratoire de Météorologie Dynamique, Univ. Pierre et Marie Curie, France; 3: Laboratoire Atmosphères, Milieux, Observations Spatiales, Univ. Versailles Saint Quentin, Guyancourt, France; 4: NASA GSFC, Greenbelt, Maryland, USA; 5: Laboratoire de Météorologie Dynamique, CNRS, France
We document, for the first time, how detailed vertical profiles of cloud fraction change diurnally between 51°S and 51°N, by taking advantage of 15 months of measurements from the Cloud-Aerosol Transport System (CATS) lidar on the non-sun-synchronous International Space Station (ISS). In the Tropics, we compare CATS observations to the diurnal cycles of water vapor profiles and top-of-the-atmosphere radiation revealed by the several sensors onboard the Megha-Tropiques low-orbiting platform.
We explore the diurnal cycles of low-level and high-level clouds over the course of the day globally and in several large regions during the boreal summer. We find distinct behaviours for high clouds over the tropical ocean, for mid-level clouds over tropical land, and for the omnipresent low and high level clouds over the Southern Ocean. Over all continental areas, we see boundary layer clouds develop upwards following sunlight activation and reach maximum occurrence at about 2.5km a.s.l. early in the afternoon.
We find that the cloud profiles derived from CATS measurements at local times of 01:30 and 13:30 are consistent with those observed from CALIPSO at similar times. Our results suggest that CALIPSO measurements, always sampled at local times of 01:30 and 13:30, document the daily extremes of the cloud fraction profiles, most accurately over ocean. These findings are applicable to other instruments with similar local overpass times, including all the other A-Train instruments and the upcoming EarthCARE mission.
Finally, two robust behaviours in tropical regions dominated by subsidence are explained by comparison with Megha-Tropiques measurements: 1) over ocean, a positive anomaly of opaque clouds in the lower atmosphere grows from sunset to sunrise, dampening the diurnal variation of oceanic surface temperature. 2) over land, a positive relative moisture anomaly near the surface at sunrise turns into a positive anomaly of opaque clouds in the free troposphere in the early afternoon, and into a near-tropopause thin clouds positive anomaly early at night, before vanishing with sunrise. This results in a strong surface temperature diurnal variation (17K).
Leveraging Upcoming 355-nm Channels in Space Lidars for Cloud Science: Comparison With 532-nm and Case Studies from the IPRAL Ground-Based Lidar
Chiriaco, Marjolaine (1); Chepfer, Hélène (1); Noël, Vincent (2); Pietras, Christophe (1) - 1: IPSL, France; 2: LA, France
After ten years of CALIPSO lidar record, there are now no doubt that lidar is one of the most powerful tool to study cloud physics. Recent study (Chepfer et al. 2018) also shows that providing a long enough time series, lidar allows studying cloud trends. CALIPSO which works at 532 nm is at the end of life, but other lidar mission with 355-nm laser are planned or just launched: ADM-Aeolus, while not designed for clouds (only few vertical levels) could be very useful (among others) to make junction between CALIPSO and future other lidar missions, EarthCare, and other future lidar missions that are under study in the agencies and institutes. It is then necessary to study how continuity can be ensured between CALIPSO cloud products and upcoming space lidars that have different wavelengths, and what is the added value of this new wavelength for clouds.
Here, the objective is then to study how leveraging upcoming 355-nm channels in space lidars for cloud science.
To address this question, we use IPRAL lidar located in the SIRTA ground-based observatory (near Paris, France): IPRAL is a high-performance backscatter lidar that works at three wavelengths including 532- and 355-nm channels. It crosses atmosphere from ground to 20 km at a 15-m vertical resolution. We will present work on: (i) the creation of the equivalent of GOCCP CALIPSO cloud product from IPRAL 532-nm channel, and the adaptation of the method for the IPRAL 355-nm channel in order to make them as consistent as possible; (ii) comparison to CALIPSO for some collocated cases study in order to qualify and quantify the limits of a possible 532/355 continuity cloud product; (iii) new diagnostics relevant for cloud science based on the 355-nm IPRAL signal analysis.
Towards a new scientific data product of H2O/HDO vertical columns from TROPOMI 2.3 μm reflectance measurements
Schneider, Andreas (1); Borsdorff, Tobias (1); aan de Brugh, Joost (1); Birk, Manfred (2); Wagner, Georg (2); Landgraf, Jochen (1) - 1: SRON Netherlands Institute for Space Research, The Netherlands; 2: DLR-IMF German Aerospace Center, Remote Sensing Technology Institute, Oberpfaffenhofen, Germany
In this study, the Shortwave Infrared CO Retrieval (SICOR) algorithm is deployed on reflectance measurements in the 2.3 μm spectral range from the Tropospheric Monitoring Instrument (TROPOMI) on ESA's Sentinel 5-P mission to simultaneously retrieve vertical column abundances of H2O and HDO. Information about the isotopic fractionation in the atmosphere allows to conclude on the atmospheric transport of air parcels and by that is highly relevant, for example, for investigations of the hydrological cycle. We present first results of TROPOMI H2O/HDO retrievals and a comparison with ground based measurements of the Total Carbon Column Observing Network (TCCON). Furthermore, we discuss the relevance of recent developments in spectroscopical databases for water vapour isotopologues. This contribution is the first step towards a scientific H2O/HDO TROPOMI data product which will enable new research possibilities.
Total Column Water Vapour Results from Sentinel-5P derived by the AMC-DOAS Method
Küchler, Tobias; Noël, Stefan; Bovensmann, Heinrich; Burrows, John - University of Bremen, Germany
Water vapour is a key component of the hydrological cycle. It is also the most important natural greenhouse gas and plays a key role in tropospheric chemistry, as source of the hydroxyl radical, OH, and as a third body in key reactions of hydroperoxyl radical, HO2. Its amount is highly variable and is also affected by anthropogenic global warming. To investigate these effects, long time series of global water vapour amount and distribution are required.
The Air Mass Corrected Differential Optical Absorption Spectroscopy (AMC-DOAS) approach to derive global water vapour vertical columns was originally developed for Global Ozone Monitoring Experiment (GOME) on ERS-2, but has been applied also to measurements of the SCIAMACHY instrument on ENVISAT and the GOME-2 instruments on METOP-A and METOP-B. An application of the AMC-DOAS method to TROPOMI data on Sentinel-5P is currently under development.
In this presentation, we show first promising results from our research. These include comparisons with independent data sets to assess the quality of the derived data. Since there is currently no operational water vapour product from Sentinel-5P, the new AMC-DOAS product will provide a valuable addition to the Sentinel 5P project. In combination with GOME, SCIAMACHY and GOME-2 data it will be possible to produce a consistent long term time series of AMC-DOAS global water vapour amounts from which e.g. global and local trends can be derived.
Total Column Water Vapour (TCWV) in the Visible „Blue“ Spectral Range: Validation and Comparisons Between GOME-2, OMI, and TROPOMI
Borger, Christian; Beirle, Steffen; Dörner, Steffen; Sihler, Holger; Wagner, Thomas - Satellite Remote Sensing Group, Max Planck Institute for Chemistry, Germany
Atmospheric water plays a key role for the Earth's energy budget and temperature distribution via radiative effects (clouds and vapour) and latent heat transport and the distribution and transport of water vapour is closely linked to atmospheric dynamics on all scales. In this context, global monitoring of the water vapour distribution is essential for numerical weather prediction, climate modeling and the understanding of climate feedbacks.
Total column water vapour (TCWV) was first retrieved using Differential Optical Absorption Spectroscopy (DOAS) analysis in the „red“ spectral range (620-670nm) as implemented in the GOME Data Processor GDP, because of the relatively strong water vapour absorption in that spectral range. However, this method has some limitations: several post-corrections e.g. due to non-linear effects (for strong water vapour absorptions) have to be applied and the low ocean surface albedo leads to low sensitivity for near-surface layers. In addition some of the new satellite sensors do not cover the red spectral range, e.g. TROPOMI on board ESA's Sentinel 5 Precursor.
Here, we apply a new approach using the spectral absorption structures of H2O in the „blue“ spectral range (430-450nm). It has the advantage that nonlinear effects are negligible. Also, this spectral window shows a higher sensitivity for near-surface layers over ocean and in general a smoother spatial distribution of the surface albedo compared to the red spectral range.
The retrieval uses a linear least-squares fit and is performed on a single spectral window, which enables a fast and robust processing of large data sets. In the retrieval spectral absorption by NO2, O3, O4 and the Ring effect are considered in addition to H2O. Furthermore, changes of the instrument spectral resolution function (ISRF) along the satellite‘s orbit are accounted for using a linearized treatment of ISRF parameters as pseudo-absorbers.
We use this new algorithm for retrieving TCWV from TROPOMI spectra and compare these results with TCWVs retrieved from OMI and GOME-2 spectra. In addition we show first results of a validation study using a variety of different reference data sets.
Total Water Vapour Retrieval from Sentinel 3a/b OLCI Measurements
Fischer, Juergen; Preusker, Rene - Free University Berlin, Germany
Total Column Water Vapour (TCWV) retrievals from measurements of the polar orbiting, sun-synchronous satellite spectrometers OLCI (Ocean and Land Colour Instrumenton board Sentinel-3) enable observations of high spatial resolution and accuracy over land surfaces on a global scale. We have validated the TCWV product as retrieved from OLCI measurements by means of GNSS (PGS), MW (Micro-Wave), and AERONET observations of TCWV.
A high agreement could be found between ground-based and satellite measurements, however, a wet-bias of up to 10% of the OLCI TCWV retrievals have been identified. This finding has to be further analysed with respect to failures in the spectroscopy and stray-light correction.
The Direct Inversion of the Continuity Equation: A Climatology of Middle Atmospheric Circulation
von Clarmann, Thomas; Grabowski, Udo; Glatthor, Norbert; Kellmann, Sylvia; Stiller, Gabriele - KIT, Germany
We use the method of the direct inversion of the continuity equation to infer 2D-fields of middle atmospheric circulation vectors (von Clarmann and Grabowski, Atmos. Chem. Phys., 16, 14563-14584, 2016) from MIPAS measurements of SF6, CFC-11, CFC-12, HCFC-22, CCl4, CH4, N2O, CO and H2O. This novel method avoids the well-known problems associated with the use of the age of stratospheric air as a diagnostic of the intensity of the Brewer-Dobson circulation, because no age spectra are needed; subsidence of mesospheric air depleted in the target species is properly accounted for by an observational upper boundary condition; and the analysis of the circulation is well resolved in space and time. Resulting circulation patterns show the variability of the Brewer Dobson Circulation and the mesospheric overturning circulation in unprecedented detail. We present multi-annual monthly mean circulation patterns along with their inter-annual variabilities and discuss prominent features of the circulation.
16:20 - 18:10
Aeolus Products for Atmospheric Dynamics
Stoffelen, Ad - KNMI, The Neatherlands
With the successful launch of Aeolus, expectations are raised with respect to high-quality Aeolus products and their beneficial application in weather forecasting, climate research and atmospheric sciences. In the presentation the planned Aeolus product development and Cal/Val will be briefly described and put in the context of the global observing system and of atmospheric modelling capabilities, in particular with respect to weather, atmospheric circulation, transport and clouds.
Expected Impact of the Aeolus Line-Of-Sight Winds in Limited-Area Models Over Europe
Šavli, Matic; Žagar, Nedjeljka - University of Ljubljana, Slovenia
The potential impact of the Aeolus horizontal line-of-sight (HLOS) winds has been extensively studied by using the global ECMWF variational data assimilation system. In preparation for the use of HLOS winds in mesoscale NWP systems in Europe, we have developed a mesoscale ensemble Kalman filter (EnKF) data assimilation system nested in the 50-member operational ECMWF ensemble prediction system (ENS). The applied Weather Research and Forecast model (WRF) and the ensemble adjustment Kalman filter (DART/WRF) over Europe and North Atlantic was used to carry out a series of the observing system simulation experiments (OSSEs) with the HLOS winds.
The impact of HLOS winds in the assimilation depends on the direction of sight with respect to the observed flow and on the assimilation methodology which spreads the impact of HLOS observations to the two wind components and other analyzed variables using the background-error covariances.
The comparison of OSSE experiments with a single wind component and full wind information and temperature data showed that the information content of HLOS winds is on average divided linearly between the zonal and meridional wind components depending on the observation azimuth. The assimilation of wind information in terms of the HLOS component may produce better analysis than the assimilation of the zonal and meridional winds in individual cases of interest for mesoscale prediction, as demonstrated in the case for fronts in the Northern Atlantic. Multivariate aspects of EnKF also provide significant analysis increments, especially if the HLOS observation is aligned along the front.
Aeolus does not provide horizontally high resolution observations, but the processing software Level-2B allows tuning of the accumulation length which controls the accumulation of measurements at about 3 km resolution to a single HLOS profile observation. Extensive sensitivity experiments both the Rayleigh and Mie retrieval suggest a promising impact of the Mie retrieval with reduced accumulation length for the purpose of mesoscale model assimilation.
Interaction and Propagation Characteristics of Gravity Waves from Different Sources Observed by Airborne and Spaceborne Infrared Sounders
Krisch, Isabell (1); Preusse, Peter (1); Strube, Cornelia (1); Ern, Manfred (1); Ungermann, Jörn (1); Hoffmann, Lars (2); Friedl-Vallon, Felix (3); Riese, Martin (1) - 1: Institute for Energy and Climate Research - Stratosphere, Forschungszentrum Jülich, Germany; 2: Jülich Supercomputing Centre, Forschungszentrum Jülich, Germany; 3: Institut für Meteorologie und Klimaforschung, Karlsruher Institut für Technologie, Karlsruhe, Germany
Gravity waves are oscillations in wind velocity and temperature with buoyancy as a restoring force. They transport energy and momentum through the atmosphere. In this way, they couple different compartments with each other and influence prominent circulation patterns in the stratosphere and mesosphere. Within the ESA study GWEX (Gravity Wave Experiment), an aircraft campaign has been performed in winter 2015/2016 to study the propagation of gravity waves. During this campaign, the first 3D tomographic measurements of gravity waves were taken with the infrared limb imager GLORIA (Gimballed Limb Observer for Radiance Imaging of the Atmosphere). The 3-D nature of the GLORIA measurements enables the determination of 3-D wave vectors, including the horizontal directions and orientation resolved momentum fluxes. This full wave characterization enables the use of ray-tracing models to identify the gravity wave sources and study their propagation.
A gravity wave event above southern Scandinavia has been probed with GLORIA on the 28 January 2016. This event is characterized by a complex situation where gravity waves from two different source mechanisms, orography and jet excitation, propagate through each other. This crossing of the waves is investigated using the GLORIA measurements, ray-tracing studies and ERA5 reanalysis data. The mountain waves propagate more or less straight upwards, whereas the jet-generated waves propagate more horizontal. The linear ray-tracing results show an excellent agreement with ERA5.
In the middle stratosphere, the results of both models are compared to measurements of the Atmospheric Infrared Sounder (AIRS) satellite instrument. Due to the relatively short vertical wavelengths of less than 15 km at 35 km altitude and the coarse vertical resolution of nadir viewing satellite instruments, the wave signatures are strongly suppressed in AIRS temperatures. However, not only the amplitudes of the waves are underestimated, also the vertical wavelengths are overestimated. Only by including an extended observational filter for the AIRS instrument into the comparison good agreements to the models are achieved.
Atmospheric Gravity Waves Observed by the GLORIA Limb Imager in the Frame of GWEX
Preusse, Peter; Krisch, Isabell; Ungermann, Joern; Ern, Manfred - Forschungszentrum Juelich GmbH, Germany
The Gimballed Limb Observer for Radiance Imaging of the Atmosphere (GLORIA) was deployed in January 2016 on board of the German research aircraft HALO to observe gravity waves. Two research flights dedicated to investigate gravity waves were conducted in the frame of the ESA study GWEX (Gravity Wave EXperiment). GLORIA observes thermal infrared emissions and has the unique capability to view the same volume of air under different angles. In this way, the 3D temperature structure of the atmosphere can be recovered using tomographic retrievals. These 3D temperature fields are used to identify gravity waves inside the measurement volume and determine the 3D wave vector, infer gravity wave momentum flux and conduct propagtion studies. The first event investigated during GWEX was a complex superposition of mountain waves above Iceland, measured on 25-January-2016. Unexpected strong oblique propagation was observed. The second event occured on 28-January-2016 above Scandinavia and encompasses gravity waves from orography as well as from spontaneous imbalance. The waves propagated into the upper stratosphere, where they also could be observed by the AIRS nadir sounder, however with much reduced amplitudes and too long vertical wavelengths due to the observational filter of the nadir viewing geometry. For both events we compare the gravity wave signatures deduced from the temperatures with in situ wind measurements taken by the HALO on-board sensor system. In particular the second event is a text-book case for the polarization relations connecting the temperature and wind signatures in a gravity wave. Both cases, however, also highlight the challenges that are encountered in inferring gravity waves from wind observations. Temperature structures emphasize in particular mesoscale gravity waves, whereas vertical winds emphasize waves of very short horizotal wavelengths. In order to compare the two observations, vertical winds have to be filtered accordingly. The challenge for the horizontal wind is the separation between gravity wave signatures and the structure of the background flow in the UTLS region. The implications of these findings for analyzing global wind observations from Aeolus will be discussed.
Dealing with the Influence of Differences in Measurement Time, Space and Addressd Air Volume of Satellite and Reference Measurements on Validation Results: Presentation of an Internet-based Tool
Wüst, Sabine (1); Wendt, Verena (2); Bittner, Michael (1,3); Yee, Jeng-Hwa (4); Mlynczak, Martin G. (5); Russell III, James M. (6) - 1: DLR Oberpfaffenhofen, Germany; 2: formerly at: Environmental Research Station Schneefernerhaus, Germany; 3: University of Augsburg, Germany; 4: Applied Physics Laboratory, The Johns Hopkins University, Laurel, USA; 5: NASA Langley Research Center, Hampton, USA; 6: Center for Atmospheric Sciences, Hampton, USA
In most cases, satellite validation is based on statistical comparison with reference data. However, satellite and reference measurements do neither exactly match in time and space (mistime and misdistance) nor address the same volume of air (misintegration). Therefore, the natural atmospheric variability leads to differences between both data sets. These differences must not be interpreted in terms of a satellite’s malfunction.
Based on ECMWF ERA-40 temperature data, the expected differences due to mistime and misdistance are quantified depending on location, height and season. The results are compared to satellite and radiosonde based results. Regions of lower atmospheric variability which are optimal for satellite validation are identified.
The misintegration effect is shown for stratospheric gravity waves which are extracted from satellite and radiosonde based temperature measurements over Europe. We point out how this effect can be used for the extraction of additional information about the horizontal orientation of gravity waves in the future.
At least, an internet based tool is presented which allows the user to retrieve information about the mean differences due to mistime and misdistance for his specific location. This tool is integrated in the Alpine Data Analysis Centre (AlpenDAC) which is currently under construction and will be available via the environmental station Schneefernerhaus (UFS, www.schneefernerhaus.de), Germany.
Long-term changes of planetary waves and their impact on ozone streamer events in Europe
Küchelbacher, Lisa (1,2); Wüst, Sabine (1); Bittner, Michael (1,2) - 1: DLR, Germany; 2: Universität Augsburg
Planetary waves (PW) are global scale waves in the atmosphere, which are well-known to considerably impact weather patterns in the middle latitudes. It is widely accepted that climate change leads to a change of the meridional temperature gradient. This should, in turn, change the planetary wave activity (PW-activity); the mid-latitudinal weather patterns are therefore expected to change. Moreover, planetary waves redistribute ozone in the stratosphere and wave breaking can lead to ozone streamer events. As such streamers are characterized by significantly reduced ozone column concentrations. They do not only impact the UV-radiation intensity which reaches the surface and which has consequences for human health. The reduced absorption of UV radiation also impacts the solar heating of the atmosphere which in turn has consequences for atmospheric dynamics.
In order to find out if the PW-activity has already changed and to observe streamer events, we use satellite based ozone total column measurements (GOME) and ERA–Interim temperature data (0 and 65 km height). We derive a measure for the PW-activity, the so-called dynamical activity index (DAI).
A general increase of the PW-activity in the stratosphere is evident from our analysis. Using the empirical mode decomposition (EMD) we are able to extract nonstationary signals of the time series. We find that longer term oscillations (QBO, ENSO, solar cycles) have a noticeable impact on the wave activity variability in all considered heights. This long-term modulation affects the overall trend of planetary wave activity. First preliminary results indicate that planetary waves favor breaking at the North Atlantic / European region. Accompanied, we observe a high frequency of ozone-streamer events in this area. As a consequence of the increase of PW-activity, the streamer frequency should also have changed.
Aeolus wind measurements will help to further study planetary wave breaking and characterize the impact on the European ozone concentration in unprecedented detail.
Wind Tracing From Observations of Atmospheric Composition
Zaplotnik, Žiga; Žagar, Nedjeljka - University of Ljubljana, Slovenia
A growing concern about the global air quality, as well as the risks connected to the changing climate has led to a large increase in satellite remote sensing of atmospheric composition which provides observations of the vertical aerosol profiles (in form of aerosol extinction coefficients). The amount of data will be further increased with the recent launch of the Aeolus satellite and the forthcoming launch of EarthCARE satellite. Meanwhile, the weather prediction problem has changed from forecasting the basic meteorological variables to predicting also the atmospheric composition that requires description of aerosol dynamics in the NWP models. These two factors provide a strong motivation to explore the potential of tropospheric aerosols as the carriers of wind information.
We present a new model of intermediate complexity to simulate the aerosol, moisture, temperature and wind interactions in 4D-Var. The model has been employed for studying the wind tracing using aerosol data using the OSSE type of experiments. We shall present numerical modelling results that provide the upper bound of estimated usefulness of the aerosol observations in the wind tracing. It is shown that the wind tracing in 4D-Var strongly depends on the spatial density and accuracy of the tracer observations as well as the frequency of observation update and the assimilation window length. The first two are needed to describe the spatial gradients of tracers and the last two provide information about the advection. In the case of linear flow, the observation spatial sampling is much more important than their update frequency. For the nonlinear flow, the opposite applies. The desired spatial resolution of observations is mainly a function of the flow properties; the faster the flow, the less dense tracer observations are needed to deduce the winds.
An important goal of further research is to estimate the wind tracing potential in the case of unknown (unrepresented) sources. First results reveal a linear dependence of the wind analysis accuracy on the ratio of the local tracer source rate and the strength of the advection.
Furthermore, ongoing research deals with the wind tracing in a saturated atmosphere. We illustrate how nonlinearities of moist processes near saturation in the combination with the aerosol wet deposition and couplings between the aerosol, moisture and dynamics have a detrimental impact on wind tracing from aerosol data.
08:30 - 10:05
Living up to Full Potential - How Combined Earth Observation-model Approaches Advance SPARC/IGAC Science
Hegglin, Michaela - University of Reading, United Kingdom
Over the past decades, the increasing capabilities of Earth observation (EO) satellites have unleashed opportunities for improved global observations of key parameters governing Earth system processes. However, the full scientific exploitation of this capability requires continued efforts both to bring observational products to full maturity and to develop suitable Earth-system models that can help with the exploitation of the available data sets. Enhanced collaboration between the modelling and observing communities are thereby key to the success of these endeavours. The World Climate Research Programme’s SPARC and Future Earth’s IGAC core projects seek to foster such collaboration and advance our knowledge of chemistry-climate interactions in the stratosphere and the troposphere based on both models and observations. Some examples are shown from ESA/SPARC’s SPIN collaboration, the SPARC Data Initiative, the SPARC Chemistry-Climate Model Initiative, and the new ESA Water_Vapour_cci to illustrate the potential of such approaches.
ALTIUS Earth Watch Element: Project Implementation and Status
Navarro Reyes, Daniel (1); Bernaerts, Dirk (1); Montrone, Luciana (1); Santandrea, Stefano (1); Sarna, Karolina (1); Wehr, Tobias (1); Frommknecht, Bjoern (2); Fussen, Didier (3) - 1: ESA/ESTEC, The Netherlands; 2: ESA/ESRIN, Italy; 3: BISA, Belgium
ALTIUS is a limb sounder mission for the monitoring of the distribution and evolution of stratospheric ozone at high vertical resolution in support of operational services and long term trend monitoring. The ALTIUS mission will provide detailed stratospheric ozone profiles information at high vertical resolution, which adds valuable information to total column ozone used for data assimilation systems by operational centres based on nadir sounders.
The ALTIUS data will also be of high importance for the atmospheric modelling community, for use as input to climate models and their validation. It will reduce a gap in high-resolution limb observation data. It has the potential to contribute to the GCOS (Global Climate Observing System) ozone profile ECV (Essential Climate Variable). Off-line ALTIUS products are relevant for the validation of the Copernicus Atmosphere Monitoring Service (CAMS) model.
The preparation and implementation of the design, development, and validation phases (B2/C/D) of ALTIUS are currently being performed as part of the ALTIUS Element in the Earth Watch Programme with participation of Belgium, Canada, Luxembourg and Romania. The activities of this ALTIUS Earth Watch Element will end with the successful conclusion of the ALTIUS Flight Acceptance Review of the Space Segment and the Ground Segment Acceptance Review, with the following objectives:
Launch, in-orbit commission and routine operation are subject of a future project proposal to be approved by the participating states.
A Mission Advisory Group (MAG) has been established with independent advisors from data users and scientific institutes to advice the project team.
The paper will present the details of the Project, its implementation and status.
Sensitivity of FORUM/EE9 to trace gases, ice clouds and surface properties
Dinelli, Bianca Maria (1); Maestri, Tiziano (2); Del Bianco, Samuele (3); Di Roma, Alessio (2); Palchetti, Luca (4); Ridolfi, Marco (2,4); Castelli, Elisa (1); Cossich, William (2) - 1: ISAC-CNR, Bologna, Italy; 2: DFA-Universita' di Bologna - Italy; 3: IFAC-CNR, Sesto Fiorentino (FI) - Italy; 4: INO-CNR, Sesto Fiorentino (FI) - Italy
The instrument FORUM (Far-infrared Outgoing Radiation Understanding and Monitoring), has been selected to compete for the next Earth Explorer 9 mission. The primary goal of the FORUM mission is the characterization of the Outgoing Longwave Radiation in the far-infrared and in the middle infrared regions, from 100 to 1600 cm-1. During the preparatory stage of the proposal, several studies have been performed to address the capability of the proposed instrument to provide information on important climate variables like surface temperature and emissivity, vertical distributions of humidity, Temperature, trace gases, and ice clouds. Here we summarize the results of these sensitivity studies.
Stratospheric Ozone Trend Assessments : Results and Lessons Learned by LOTUS
Hubert, Daan (1); Petropavlovskikh, Irina (2,3); Godin-Beekmann, Sophie (4); Damadeo, Robert (5); Hassler, Birgit (6,7); Sofieva, Viktoria (8); Frith, Stacey (9); Tourpali, Kleareti (10) - 1: Royal Belgian Institute for Space Aeronomy (BIRA-IASB), Brussels, Belgium; 2: Cooperative Institute for Research in Environmental Sciences (CIRES), University of Colorado, Boulder, CO, USA; 3: NOAA Earth System Research Laboratory, Global Monitoring Division (GMD), Boulder, CO, USA; 4: LATMOS, Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Centre National de la Recherche Scientifique (CNRS), Guyancourt, France; 5: NASA Langley Research Center, Hampton, VA, USA; 6: Bodeker Scientific, Alexandra, New Zealand; 7: German Aerospace Center (DLR), Institute of Atmospheric Physics, Oberpfaffenhofen, Weßling, Germany; 8: Finnish Meteorological Institute, Helsinki, Finland; 9: Science Systems and Applications Inc., Lanham, Maryland, USA; 10: Lab. of Atmospheric Physics, Aristotle University of Thessaloniki, Greece
WMO/UNEP Scientific Assessments of Ozone Depletion require accurate evaluations of long-term ozone trends and their uncertainty and attribution. Detailed studies of observations and model data allow to evaluate the success of the Montreal Protocol with regards to the recovery of the ozone layer and to make realistic projections of atmospheric ozone into the next decades. The 2014 Ozone Assessment concluded that observations showed a statistically significant recovery in the upper stratosphere. In 2015, the SI2N initiative reported –based on different data records and different analysis methods and assumptions– that upper stratospheric recovery was not necessarily significant. This apparent tension inspired a new coordinated activity endorsed by SPARC, IO3C and WMO (GAW) named LOTUS (Long-term Ozone Trends and Uncertainties in the Stratosphere). It aimed primarily at gathering the profile ozone community to reach a wide consensus on the significance of stratospheric ozone trends prior to the 2018 Ozone Assessment. LOTUS succeeded in this goal, taking advantage of state-of-the-art profile ozone Climate Data Records and chemistry-climate models and analysis tools to not only estimate ozone trends but also to establish best practices for data handling/merging and for regression analyses. We present the methodologies applied for this effort and summarize the main conclusions related to stratospheric ozone recovery between 2000 and 2016. We also look forward and emphasize lessons learned by LOTUS and in particular the challenges for ozone CDR developers and providers such as ESA’s Climate Change Initiative and EC’s Copernicus Climate Change Service.
Assessment of Quality of MIPAS ESA V8 Products Before Full Mission Reprocessing
Raspollini, Piera (1); Barbara, Flavio (1); Bianchini, Massimo (2); Birk, Manfred (3); Castelli, Elisa (4); Ceccherini, Simone (1); Dehn, Angelika (5); Gai, Marco (1); Dinelli, Bianca Maria (4); Dudhia, Anu (6); Flaud, Jean-Marie (7); Hoepfner, Michael (8); Hubert, Daan (9); Keppens, Arno (9); Kiefer, Michael (8); Kleinert, Anne (8); Moore, David (10); Papandrea, Enzo (4,11); Perron, Gaetan (12); Piro, Alessandro (11); Lopez-Puertas, Manuel (13); Oelhaf, Hermann (8); Pettinari, Paolo (4); Remedios, John (10); Ridolfi, Marco (14,15); Sgheri, Luca (16); Wagner, Georg (3); Wetzel, Gerald (8); Zoppetti, Nicola (1) - 1: IFAC-CNR, Florence, Italy; 2: ISC-CNR, Florence, Italy; 3: DLR, Germany; 4: ISAC-CNR, Bologna, Italy; 5: ESA/ESRIN, Frascati, Italy; 6: Oxford University, Oxford, UK; 7: LISA-CNRS, Univ.Paris 12 et 7, France; 8: KIT-IMK, Karlsruhe, Germany; 9: BIRA-IASB, Belgium; 10: University of Leicester, UK; 11: SERCO SpA c/o ESA/ESRIN, Frascati, Italy; 12: ABB Inc., Quebec, Canada; 13: IAA-CSIC, Granada, Spain; 14: INO-CNR, Florence, Italy; 15: University of Bologna, Bologna, Italy; 16: IAC-CNR, Florence, Italy
The Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) is a limb-viewing infrared Fourier transform spectrometer that operated from 2002 to 2012 onboard the ENVISAT satellite. The maintenance and the upgrade of both L1 and L2 ESA processors are accomplished by the Quality Working Group, where a fruitful collaboration among Level 1, Level 2 and validation teams can be exploited. Recently both ESA L1 and L2 processors have been updated, as well as the spectroscopic database and some absorption cross-sections. In addition to the products already present in the current release (V7) of ESA MIPAS data (temperature and the VMR of H2O, O3, HNO3, CH4, N2O, NO2, CFC-11, CFC-12, N2O5, ClONO2, HCFC-22, COF2, CF4, HCN and CCl4), the VMR of six additional species (OCS, CH3Cl, HDO, C2H2, C2H6, COCl2) will be provided in V8 dataset. In preparation of V8 full mission reprocessing, three Diagnostic Datasets have been generated to check the performances of all L1, L2 processors and the new auxiliary data.
The analysis of these Diagnostic Datasets and the comparison with previous full mission dataset V7 will be used to perform a first assessment of the quality of the new V8 products. In the paper special focus will be given to the new species.
10:35 - 12:25
Current state-of-play of the Copernicus Atmospheric Monitoring Service (CAMS)
Peuch, Vincent-Henri - ECMWF, United Kingdom
CAMS is one of the six thematic services of Copernicus (http://atmosphere.copernicus.eu). It delivers operationally consistent and quality-controlled air quality forecasts at the global and regional (Europe) scales, as well detailed information related to air pollution, solar energy, greenhouse gases, surface emissions and climate forcing. CAMS is a truly European effort: it is implemented by ECMWF on behalf of the European Union and involves over 130 entities from 28 countries through about 50 contracts.
The CAMS global forecasting system is using ECMWF's Integrated Forecasting System (IFS), which is used for Numerical Weather Prediction and has been extended with modules for atmospheric chemistry, aerosols and greenhouse gases. The CAMS system assimilates observations from more than 70 satellite sensors to constrain both the meteorology and the atmospheric composition species. The system is continuously developed to provide the best possible products to the users: current efforts on model developments an on improving the data assimilation system for satellite observations of atmospheric composition will be discussed.
The presentation will especially focus on two topics illustrating the current state-of-play with CAMS. The CAMS reanalysis covering the period 2003-2016 has been released in last September; we’ll illustrate some aspects of the production and of the validation of this dataset, which is expected to be used by several thousand users worldwide. Second, we’ll provide some information about the uptake in CAMS of Sentinel-5P’s key data products (ozone, NO2, SO2, CO, CH4, HCHO) discussing in particular the synergies that have been at play with the developers of the different retrievals and facilitated speedy development, release and uptake of the operational products.
Finally, the success of CAMS is through the uptake of the products and the success of its users. We’ll describe a few success stories, such as the selection of CAMS air quality outputs by The Weather Chanel for its web & mobile platforms as well as for the default weather application of Apple iOS 12, which was released at the end of September. This, together with European Air Quality bulletins broadcast several times daily on Euronews, allows CAMS products reaching an audience of several tens of millions.
Towards 1 x 1 km2 High Resolution Air Quality and Emission Monitoring from Space: Current and Future Potential of Satellite Instruments like OMI, TROPOMI and TROPOLITE
Levelt, Pieternel Felicitas (1,2); Veefkind, Joris Pepijn (1,2); Aben, Ilse (3); Joiner, Joanna (4); Tamminen, Johanna (5); Bhartia, Pawan (4) - 1: KNMI, Netherlands, The; 2: University of Technology Delft; 3: SRON; 4: NASA GSFC; 5: FMI
The growth of human population and the industrialization in the 19th and 20th century has led to dramatic changes in the Earth atmosphere. Especially the chemical composition of the atmosphere is rapidly changing as a result of human activities. We entered the “anthropogenic” epoch, where the activities of humans play a key role in the further development of the ozone layer, air quality and climate change.
The rapid development of megacities and the strong development in the Asian countries are clear examples of the large changes that effected the atmosphere in the last decades and will continue to do so in future. In the coming decades air pollution in megacities will continue to be a major area of concern and the need for timely, high resolution information on emissions will increase. With the Paris climate agreement, the mitigation paragraph of climate change was put on the agenda, and ways to assess globally the effectiveness of emission control policy measures become more and more important, for as well land as ship emissions.
Measurements from space are therefore urgently needed to help society to deal with the challenges we have to overcome in the air quality and climate domain. The current instrumentation will make it possible to really make this step towards society, not only on the global and regional domain, but even on the local domain. In order to understand sentinel 5p/TROPOMI’s measurements and trends, we will need to lay contact with local scientists and scientific and governmental organizations residing in the area’s measured, since a detailed understanding of the emission sources and changes, local atmospheric circumstances etc. will often be needed for the correct interpretation of the data. TROPOMI will therefore be a game changer for our field, it will enable the step towards use of satellite data for the challenges society has in order to control its emissions.
In this presentation the possibilities satellite data can provide society to help overcoming its challenges in the next decades in the air quality and climate domain will be presented, using clear examples of the OMI instrument and the first amazing results of the sentinel 5 precursor/TROPOMI instrument. An outlook will be presented on what new satellite instrumentation going towards a 1 x 1 km2 spatial resolution could bring.
Increasing the Societal Impact of Satellite-Based Observations for Air Pollution Monitoring: Preparing for TROPOMI/S5P Data Exploitation
Ialongo, Iolanda; Virta, Henrik; Sundström, Anu-Maija; Hakkarainen, Janne - Finnish Meteorological Institute, Finland
Monitoring the effect of human activity on the atmospheric composition has become more and more important for protecting both environment and human health. Satellite observations have been extensively used to monitor air quality because of their mapping capability and availability with global coverage. They are particularly important over areas where ground-based measurements are not performed or not publicly available. For example, satellite observations are suitable for monitoring the changes in polluting emissions from different kind of sources, such as car traffic, industry, ships and energy production. Furthermore, satellite observations are freely available and offer an opportunity to build financially sustainable services.
This work presents several successful applications of satellite-based data for air quality monitoring to support both public and private sector, with particular focus on Finnish society. The activities are implemented as pilot projects, based on the interaction between researchers and identified users. The results are mostly based on the space-based observations of atmospheric concentrations of nitrogen and sulfur dioxide.
Some of the topics covered in these applications are: (1) Satellite-based air quality monitoring in Helsinki area for local environmental authorities and oil sector company operating in the area. (2) Satellite-based SO2 emission monitoring to support Finnish Cleantech companies operating in the metal smelting industry sector. (3) Satellite-based air pollution observations as background information and training material in FMI international cooperation project with developing countries.
Also, we will present the most recent results from TROPOMI/S5P observations in Helsinki, including their comparison with ground-based measurements and their potential for societal applications. Also, we will show how the experience gained in users’ engagement will be useful for future applications, e.g. using TROPOMI data and in preparation for planned anthropogenic CO2 missions.
These activities are funded under of the Key project funding by the Academy of Finland “Forging ahead with research” through the ILMApilot project. The goal is to boost the societal impact of research by promoting scientific research and its application. The research activities have been also supported by ESA, via the Living Planet fellowship programme.
Downscaling Satellite-based Air Quality Products
Schneider, Philipp (1); Stebel, Kerstin (1); Ajtai, Nicolae (2) - 1: NILU - Norwegian Institute for Air Research, Norway; 2: Faculty of Environmental Science and Engineering, Babeş-Bolyai University, Cluj-Napoca
Operational satellite-based Earth Observation products for air quality applications tend to have a relatively coarse spatial resolution on the order of several kilometers to tens of kilometers. While the Sentinel-5P/TROPOMI instrument with its 7 km x 3.5 km footprint at nadir provides significantly improved spatial detail compared to previous satellite instruments, it is not yet sufficient for air quality applications within a city, where spatial gradients are often sharp and citizen exposure to air pollution varies significantly from street to street.
In order to address this issue we have developed a spatial downscaling technique for satellite-based air quality products. This was carried out as part of the ESA-funded project SAMIRA (“SAtellite based Monitoring Initiative for Regional Air quality”). The method applies geostatistics and a temporally static or dynamic high-resolution proxy dataset to downscale the satellite information from the original Level-2 pixel geometry to any arbitrary (usually regular) high-resolution pixel geometry. The method applies a combination of area-to-point kriging and regression and essentially combines a high-resolution but often biased proxy dataset with the coarse-resolution but assumed to be unbiased satellite observations, and as such adds value to both datasets. The method can be used directly on Level-2 swath data without the need for prior gridding. It is further capable of providing pixel-level uncertainty estimates taking into account the original product uncertainty and the uncertainty introduced by the downscaling.
We demonstrate the methodology with data from Aura/OMI and Sentinel-5/TROPOMI. We focus here primarily on nitrogen dioxide (NO2), but the algorithm is generic and can be used for other species as well. As spatial proxy datasets we use high-resolution output from the EPISODE and WRF-Chem models as temporally dynamic proxy data, as well as long-term average high-resolution NO2 maps for Europe as time-invariant proxy information. We demonstrate the algorithm for selected regions in Europe with significant air quality issues (Po Valley, Ruhr area, Silesia, Warsaw, and others).
Initial results indicate that the method is capable of providing qualitatively realistic high-resolution maps (e.g. 100 m), for which the absolute values are provided by the satellite observations and the sub-grid spatial patterns are inherited from the fine-scale spatial proxy dataset. Re-aggregating the downscaled results to the original satellite pixel geometry reproduces the original values. Quantitatively, a comparison against stations observations of NO2 shows that the correlation for the downscaled maps increases significantly compared to the correlation between the original satellite dataset and the station data. Overall, the method is a first step towards exploiting the Sentinel-5P/TROPOMI data for applications at the urban scale.
Estimating air pollutant concentrations from space over China
Qin, Kai (1); Xu, Jian (2) - 1: China University of Mining & Technology, China; 2: German Aerospace Center, Germany
Due to its large spatial coverage, satellite remote sensing provides opportunities to monitor the large-scale variabilities of ground-level air quality. China is suffering from serious air pollution dominated with aerosol particles in autumn and winter, and Ozone in summer that adversely affects human health. China has built near 1500 ambient monitoring stations over 367 cities to supervise air quality improvement in China. Hourly average concentrations of air pollutants including PM2.5, NO2, SO2, and O3 from these stations are available in the National air quality publishing platform. This gives us an unprecedented opportunity to improve the space-borne estimation of air quality over China. In this presentation, aerosol optical depth (AOD) data from Moderate Resolution Imaging Spectroradiometer (MODIS) and Geostationary Ocean Color Imager (GOCI) are used to estimate ground-level PM2.5 concentration. Tropospheric NO2 and O3 columns from Ozone Monitoring Instrument (OMI) are used to estimate ground-level NO2 and O3 concentrations. In addition, meteorological variables including planetary boundary layer height, relative humidity, wind speed, air pressure, and temperature, Normalized Difference Vegetation Index (NDVI), Digital Elevation Model (DEM) and Multi-resolution Emission Inventory for China are included. Geographically and temporally weighted regression (GTWR) model and deep learning method are constructed to build the relationship between satellite products and ground measurements. Much improved estimations are achieved with large coefficient of determination (R2) and small root mean square error (RMSE). The results have profounding implication for improving our understanding of human exposure to air pollutant.
A decade of satellite-derived maritime NOx emissions over Chinese Seas
van der A, Ronald; Ding, Jieying - KNMI, Netherlands, The
Using the inversion algorithm DECSO, developed within the GlobEmission project, we derived monthly NOx emissions on a 0.25 x 0.25 degree resolution over East Asia for an 11-year period (2007 to 2017) based on OMI observations. We used these emissions to analyse trends and seasonal cycle of maritime emissions over Chinese seas. No effective regulations on NOx emissions have been implemented for ships in China, which is reflected in the trend analysis of maritime emissions. The effect of maritime emissions on the air quality over land will be discussed. Simulations by an atmospheric chemistry transport model show a notable influence of maritime emissions on air pollution over coastal areas, especially in summer. The satellite-derived spatial distribution and the magnitude of maritime emissions over Chinese seas are in good agreement with bottom-up studies based on the Automatic Identification System of ships. We will further show how the new high resolution observations of TROPOMI on Sentinel 5p are expected to enhance the accuracy of maritime emissions in the future.
IASI Measurements Of Hazardous Air Pollution Due To The Exceptional 2015 Fires In Equatorial Asia
Moore, David P; Harrison, Jeremy J; Remedios, John J - NCEO, United Kingdom
Forest fires in Indonesia are a seasonal occurrence, largely due to the agricultural practice of slash and burn in which land is cleared for new planting by cutting back vegetation and setting it on fire. During late 2015, the agricultural fires were particularly severe, due to it being an El-Niño year, impacting regional air quality.
The land in Indonesia contains a lot of peat, which easily burns to emit a variety of trace gases including hydrogen cyanide (HCN). Satellite limb instruments such as the Atmospheric Chemistry Experiment Fourier Transform Spectrometer (ACE-FTS) instrument and Microwave Limb Sounder (MLS) have revealing an unprecedented amount of HCN emitted from Southeast Asia during September–November 2015 which had been transported into the upper troposphere and lower stratosphere.
Here we present nadir observations of HCN total columns derived from the Infrared Atmospheric Sounding Interferometer (IASI) during September–November 2015. IASI observations of carbon monoxide (CO) using the University of Leicester IASI Retrieval Scheme (ULIRS) are used to calculate enhancement ratios of HCN relative to CO and ultimately derive new emission factors for Indonesian peatland which will be used to improve chemical transport models. These satellite-derived data are compared to those already in emission databases such as GFED.
13:55 - 15:25
Monitoring Airborne Hazards for Aviation Using TROPOMI Satellite Data
Stammes, Piet (1); de Laat, Jos (1); Apituley, Arnoud (1); Som de Cerff, Wim (1); Wagenaar, Saskia (1); Kok, Suzanne (1); Wotawa, Gerhard (2); Hirtl, Marcus (2); Lipok, Florian (3); Mona, Lucia (4); Sofiev, Mikhail (5); Theys, Nicolas (6); Plu, Matthieu (7); Rokitansky, Carl-Herbert (8); EUNADICS-AV Team, The (9) - 1: KNMI, Netherlands, The; 2: ZAMG, Austria; 3: BRIMATECH, Austria; 4: CNR, Italy; 5: FMI, Finland; 6: BIRA/IASB, Belgium; 7: Meteo-France, France; 8: PLUS, Austria; 9: www.eunadics.eu
Airborne hazards like volcanic plumes, desert dust clouds, and smoke from wildfires, pose a risk for aviation. Information on the location, height, type, and mass density of these aerosol plumes is important to assess the risks and warrant air safety. Remote sensing by satellites and ground-based instruments is used to provide the required observational data. The timely distribution of the information to the aviation sector is a challenge, but crucial for early warning and flight (re-)planning. In the EUNADICS-AV project an information system is being set up, as a demonstrator, consisting of observations from satellite, ground and airplane, combined with atmospheric transport modelling, to provide this information to the aviation sector.
EUNADICS-AV stands for European Natural Airborne Disaster Information and Coordination System for Aviation. The main objective of this European project is closing the significant gap in European-wide data and information availability during airborne hazards. Aviation is one of the most critical ways of transport in this century. Even short interruptions in flight schedules can cause major economic damage. Therefore, information from observations are crucial for decision making. Several satellite data sources are considered in the EUNADICS-AV project, especially from the European Meteosat (SEVIRI) and Metop (GOME-2 and IASI) satellites. Also, the Sentinel satellites which recently became available, Sentinel-3 (SLSTR) and Sentinel-5P (TROPOMI), are used as data sources.
It appears that the TROPOMI L2 data products are very useful for hazard monitoring for several reasons. First of all, TROPOMI has true daily global coverage, so all sources of events, like volcanoes, are observed daily. Secondly, the relatively high spatial resolution of 3.5x7 km2 is useful to outline the plumes accurately. Thirdly, the instrument has a high sensitivity for the presence of gases relevant to detection of airborne hazards, like NO2, SO2 and CO. Moreover, the simultaneous detection of several aerosol and trace gas products for the same area helps to identify the type of aerosols. We find that the combination of the TROPOMI L2 products: Aerosol Index, SO2, CO, and cloud/aerosol height (using the O2 A-band) leads to a strong synergy and enables discrimination of important aerosol types. We present several cases of hazardous events where the TROPOMI data products are useful for selecting the types of aerosols and estimate the plume heights.
The EUNADICS-AV project has received funding from the European Union’s Horizon 2020 research programme for Societal challenges - smart, green and integrated transport under grant agreement no. 723986.
Can we do Science with One Day of S5p-TROPOMI Data?
Beirle, Steffen; Borger, Christian; Dörner, Steffen; Wagner, Thomas - Max-Planck-Institut für Chemie, Germany
Since two decades, satellite instruments like GOME(-2), SCIAMACHY, and OMI allow the global retrieval of tropospheric NO2, with increasing spatial resolution. By temporal averaging, spatial patterns of anthropogenic sources can be clearly identified. In these averaged maps, the effective NOx lifetimes and emissions can even be quantified from the NO2 decay downwind from large NOx sources.
TROPOMI offers a high spatial resolution of 3.5 km times 7 km, which is more than 10 times better than OMI (nadir). This allows to detect also weaker sources and to partly resolve the spatial distribution of NOx sources within a megacity or urban areas. In addition, TROPOMI offers a high signal to noise ratio, leading to low noise in daily maps of tropospheric NO2, such that emission plumes from cities and large power plants are clearly visible. Thus, methods that have been applied to long-term means in the past can now be applied to daily measurements as well.
Single day measurements generally provide much higher contrast compared to temporal means, as upwind columns are lower than the mean, while downwind columns are far higher than the mean. From the upwind measurements, constraints on spatial extent of sources can be derived. From the downwind decay, a combined lifetime/emission fit can be performed on daily basis rather than for temporal means as done in previous studies. From multiple days, thus statistical analysis of the mean and variability of both NOx emissions and lifetime can be performed, allowing to investigate the consistency of the methodology and to infer temporal changes of emissions and potentially also the NO2 lifetime on daily basis.
Here we present first results of the analysis of lifetime/emission fits on daily basis, focussing on the Saudi-Arabian capital Riyadh.
The potential for synergistic Multi-Instrument Validation of TROPOMI/S5P air quality products over Thessaloniki, Greece.
Koukouli, Maria-Elissavet (1); Drosoglou, Theano (1); Siomos, Nikos (1); Gkertsi, Fani (1); Boudouri, Kelly (1); Garane, Katerina (1); Balis, Dimitris (1); Bais, Alkis (1); Loyola, Diego (2); Heue, Klaus-Peter (2); Xu, Jian (2); Zimmer, Walter (2); Romahn, Fabian (2); Pedergnana, Mattia (2); Lerot, Christophe (3); Van Roozendael, Michel (3); Desmedt, Isabelle (3); Pinardi, Gaia (3); Eskes, Henk (4); van Geffen, Jos (4); Boersma, Folkert (4); Apituley, Arnoud (4); de Graaf, Martin (4); Nanda, Swadhin (4); Veefkind, Pepijn (4) - 1: Laboratory of Atmospheric Physics, Aristotle University of Thessaloniki, Greece; 2: Deutsches Zentrum für Luft- und Raumfahrt (DLR), Institut für Methodik der Fernerkundung (IMF), Germany; 3: Royal Belgian Institute for Space Aeronomy, (BIRA-IASB), Belgium; 4: Royal Netherlands Meteorological Institute, (KNMI), De Bilt, The Netherlands
Operational monitoring of atmospheric gaseous and particular species of both tropospheric as well as stratospheric provenance sensed by satellite instruments are performed routinely in the Laboratory of Atmospheric Physics, Thessaloniki, Greece, using a suite of different ground based instruments. These include both a single and double Brewer spectrophotometer, multiple MAX-DOAS instruments, a Raman aerosol Lidar as well as a NILU-UV sun photometer, a CIMEL photometer, among others. Most of the data records provided by these instruments span the better part of two decades. In the following we will focus on validating TROPOMI/S5P total ozone columns, total, stratospheric and tropospheric NO2 and HCHO using the MAX-DOAS instruments and absorbing aerosol height using the Raman Lidar system. The high spatial resolution of the TROPOMI/S5P TOCs will permit the investigation on the effect of the temporal difference between the measurements, as well as other contributing factors.
A MAX-DOAS system has been operating since 2011 on the rooftop of the Physics Department in the Aristotle University of Thessaloniki at the Laboratory of Atmospheric Physics (LAP), which is located in the city center of Thessaloniki, Greece. A second MAX-DOAS system is operating since 2016 at the Center of Interdisciplinary Research and Innovation (CIRI) of AUTH located at the suburbs of the city, about 10 km to the South-East. The combined monitoring ability at both an urban and suburban location can prove to be extremely informative in identifying urban gradients in NO2 and HCHO loading and thus allowing their verification from high spatial resolution space-born observations, as well as possible features in the daily variability of the ozone content over the city.
A Raman Lidar system is co-located in LAP, operating since 2000 as part of the European Aerosol Research Lidar Network (EARLINET) and will be employed to examine the variability of the aerosol load via its verification to the TROPOMI/S5P Absorbing Layer Height for cases of elevated aerosol layers such as Saharan dust events and biomass burning episodes. Routine, dedicated Raman lidar measurements during such episodes, like those performed in EARLINET, are important to study the sensitivity of the newly developed S5P/ALH product for different aerosol types.
Total and Tropospheric NO2 Column Retrieval for GOME-2 and TROPOMI
Liu, Song (1); Valks, Pieter (1); Pinardi, Gaia (2); De Smedt, Isabelle (2); Yu, Huan (2); Beirle, Steffen (3); Richter, Andreas (4) - 1: German Aerospace Center (DLR), Germany; 2: Belgian Institute for Space Aeronomy (IASB-BIRA), Belgium; 3: Max Planck Institute for Chemistry (MPI-C), Germany; 4: University of Bremen, Germany
Nitrogen dioxide (NO2) plays a key role in both stratospheric and tropospheric chemistry. This contribution focuses on the algorithm development and refinement for the retrieval of NO2 columns for the GOME-2 satellite instrument. Furthermore, the improved algorithm is adapted to measurements from the TROPOMI instrument with a spatial resolution as high as 7*3.5 km2.
A larger 425-497 nm wavelength fitting window is used in the differential optical absorption spectroscopy (DOAS) retrieval of the NO2 slant column density, with corrections for the GOME-2 slit function variations over time and along orbit. The STRatospheric Estimation Algorithm from Mainz (STREAM) is optimized for the determination of the NO2 stratospheric column density. To calculate the tropospheric AMF, a new directional surface albedo database based on GOME-2 observations is used to account for bidirectional reflectance distribution function (BRDF) effect. In addition, the new version 3.0 OCRA/ROCINN cloud parameters using the more realistic Clouds-As-Layers model are applied, in which clouds are treated as optically uniform layers of light-scattering particles (water droplets).
We present the improvements in the NO2 retrieval algorithm for GOME-2 and we show validations of the GOME-2 NO2 data using ground-based MAX-DOAS measurements. We present the first results from TROPOMI and we show verifications of the TROPOMI NO2 data using GOME-2 measurements.
Satellite Based Monitoring Initiative For Regional Air Quality (SAMIRA)
Stebel, Kerstin (1); Schneider, Philipp (1); Ajtai, Nicolae (2); Stefanie, Horatiu (2); Botezan, Camelia (2); Diamandi, Andrei (3); Dumitrache, Rodica (3); Horálek, Jan (4); Ďoubalová, Jana (4); Juras, Roman (4); Benešová, Nina (4); Vlček, Ondrej (4); Nemuc, Anca (5); Boldeanu, Mihai (5); Nicolae, Doina (5); Nicolae, Victor (5); Stachlewska, Iwona S. (6); Zawadzka, Olga (6); Novotný, Petr (7); Vaněk, Lumír (7); Zehner, Claus (8) - 1: NILU - Norwegian Institute for Air Research, Kjeller, Norway; 2: Babes-Bolyai University, Cluj, Romania; 3: National Meteorological Administration of Romania, Bucharest, Romania; 4: Czech Hydrometeorological Institute, Prague, The Czech Republic; 5: INOE - National Institute of Research and Development for Optoelectronics, Margurele, Romania; 6: Institute of Geophysics, Faculty of Physics, University of Warsaw, Poland; 7: IDEA-ENVI, Prague, The Czech Republic; 8: ESA/ESRIN, Frascati, Italy
Nowadays a vast amount of operational satellite-based Earth Observations (EO) products are available, many of which have the potential to be useful for air quality applications. In order to better exploit these data, a three-year ESA funded project Satellite based Monitoring Initiative for Regional Air quality (SAMIRA) was established in 2016. The overall goal of SAMIRA is to improve regional and local air quality monitoring through synergetic use of satellite data, output from chemical transport models and data from in situ air quality monitoring networks. This is a collaborative effort of a team located in four countries (Poland, Romania, The Czech Republic, and Norway), where the capitals, the Gorj county in Romania, and the Silesia region, the border area between Poland and The Czech Republic, periodically suffer from air pollution.
We present an overview of results obtained in the first half of the project. While SAMIRA is ultimately intended as a NRT demonstration, we first concentrated on work with historical datasets, which cover the period June to September 2014. For this period WRF-Chem output was generated on a 1 km x 1 km local grid for the particular polluted areas mentioned above and on a 5 km x 5 km European grid for improved PM forecasts using in situ data assimilation.
A first activity is the further development of an algorithm for the retrieval of aerosol optical depth (AOD) from the Spinning Enhanced Visible and InfraRed Imager (SEVIRI). Visualisation of SEVIRI AOD 15 min maps and their respective uncertainties are shown for the four countries. In a next step particulate matter (PM₂.₅) is derived from SEVIRI AOD using micro-physical properties from GADS/OPAC and mass mixing ratios of aerosol species from WRF-Chem model. Look-up tables (LUT) with extinction efficiencies for a range of possible mixtures of aerosols and different humidity conditions are generated. We show hourly PM₂.₅ maps obtained with this method and present comparisons with in situ air quality station data. Data fusion techniques are employed to utilize satellite products of atmospheric composition for European- and National scale air quality mapping. The additional benefit of satellite-based monitoring over existing monitoring techniques (in situ, models) is tested by combining hourly, daily and annual data using geostatistical methods and demonstrated for nitrogen dioxide (NO₂), sulphur dioxide (SO₂), and AOD/PM for rural and urban areas. Air quality applications, in particular within a city, require very high spatial resolutions, which are not yet available from satellites. In order to address this issue we have developed a spatial downscaling technique for satellite-based air quality products. The method applies a combination of area-to-point kriging and regression and essentially combines a high-resolution but often biased proxy dataset with the coarse-resolution but assumed to be unbiased satellite observations (from Aura/OMI and Sentinel-5/TROPOMI). In a final step we summarize the validation efforts for evaluating the quality of the generated products and activities linking to interested users.
High-Resolution Nitrogen Dioxide Retrievals From S5P/TROPOMI
van Geffen, Jos (1); Eskes, Henk (1); Boersma, Folkert (1,2); Sneep, Maarten (1); ter Linden, Mark (3); van der A, Ronald (1); Veefkind, Pepijn (1,4) - 1: KNMI, De Bilt, The Netherlands; 2: Wageningen University, Wageningen, The Netherlands; 3: Science and Technology Corporation, Delft, The Netherlands; 4: Delft University of Technology, Delft, The Netherlands
The TROPOspheric Monitoring Instrument (TROPOMI) spectrometer aboard the Copernicus Sentinel-5P (S5P) satellite, launched on 13 Oct. 2017, measures several trace gases as well as some aerosol and cloud properties with a resolution of 7 x 3.5 km2 at nadir, achieving global coverage each day.
TROPOMI nitrogen dioxide (NO2) tropospheric columns are retrieved using a DOAS algorithm combined with an integrated modelling/retrieval-assimilation approach based on the TM5-MP chemistry-transport model (operating at 1x1 degree resolution), to derive air-mass factors and to estimate stratospheric columns. Developments from the EU QA4ECV project (www.qa4ecv.eu) have been included in the retrieval to ensure consistency.
This contribution describes the components of the TROPOMI NO2 tropospheric and vertical column retrieval, focussing on data quality issues and the latest improvements in the operational algorithm, as well as prospects for future developments and use of the data for monitoring NO2 sources and air quality.
Off-line NO2 data of the operational (E2) phase, started 30 April 2018, and near-real time (NRT) data as of 3 July 2018 are available from the Copernicus Open Access Hub (s5phub.copernicus.eu).
15:55 - 16:40
ESA FRM4DOAS: Towards a Quality-Controlled MAXDOAS Centralized Processing System in Support of Air Quality Satellite Sensors Validation
Hendrick, François (1); Fayt, Caroline (1); Friedrich, Martina (1); Beirle, Steffen (2); Friess, Udo (3); Richter, Andreas (4); Boesch, Tim (4); Kreher, Karin (5); Piters, Ankie (6); Wagner, Thomas (2); Tirpitz, Jan-Lukas (3); Cede, Alexander (7); Spinei, Elena (8); Dehn, Angelika (9); von Bismarck, Jonas (9); Casadio, Stefano (9); Fehr, Thorsten (10); Van Roozendael, Michel (1) - 1: Royal Belgian Institute for Space Aeronomy (BIRA-IASB), Belgium; 2: Max Planck Institute for Chemistry, Mainz, Germany; 3: Institute for Environmental Physics, University of Heidelberg, Heidelberg, Germany; 4: Institute for Environmental Physics, University of Bremen, Bremen, Germany; 5: BK Scientific, Mainz, Germany; 6: Royal Netherlands Meteorological Institute, De Bilt, The Netherlands; 7: LuftBlick, Mutters, Austria; 8: NASA-Goddard, Greenbelt, Maryland, USA; 9: ESA/ESRIN, Frascati, Italy; 10: ESA/ESTEC, Noordwijk, The Netherlands
In order to ensure that products delivered by air quality satellite sensors meet user requirements in terms of accuracy, precision and fitness for purpose, it is essential to develop a robust validation strategy relying on well-established and traceable reference measurements. In this context, the ESA Fiducial Reference Measurements for Ground-Based DOAS Air-Quality Observations (FRM4DOAS) project is aiming at further harmonizing MAXDOAS measurements. Since it provides vertically-resolved information on atmospheric gases at an horizontal scale approaching the one from nadir backscatter satellite sensors, the ground-based MAXDOAS technique has been recognized as a valuable source of correlative data for validating space-borne observations of atmospheric species such as NO2, HCHO, SO2, O, etc.
In this presentation we describe the FRM4DOAS harmonization effort which includes three main activities: (1) the specification of best practices for MAXDOAS instrument operation, (2) the selection of state-of-the art retrieval algorithms, procedures, and settings, (3) the demonstration of a centralised rapid-delivery (6-24h latency) processing system for MAXDOAS instruments, to be operated within the international Network for the Detection of Atmospheric Composition Change (NDACC). The first phase of the project, which will end in November this year, focusses on the development of 3 key products: NO2 vertical profiles, total O3 columns, and tropospheric HCHO profiles. Demonstrated at 11 MAXDOAS pilot stations operated by project partners, the system is designed to allow seamless upscaling in terms of stations and data products. These activities will contribute to guarantee that homogenous, fully traceable, and quality-controlled datasets are generated from reference ground-based UV-vis instruments. The availability of such Fiducial Reference Measurements for air quality observations is critical for the validation of present and future satellite missions like atmospheric Sentinels (5p, 4, 5) in Europe, GEMS in Asia, and TEMPO in the US.
Assimilation Of Fused Atmospheric Sentinels Data: First Results From Science To Applications
Cortesi, Ugo (1); Ceccherini, Simone (1); Del Bianco, Samuele (1); Gai, Marco (1); Tirelli, Cecilia (1); Zoppetti, Nicola (1); Bonazountas, Marc (2); Argyridis, Argyros (2); Loenen, Edo (3); Arola, Antti (4); Kujanpää, Jukka (4); Lipponen, Antti (4); van der A, Ronald (5); van Peet, Jacob (5); Tuinder, Olaf (5); Masini, Andrea (6); Simeone, Emilio (6); Dragani, Rossana (7); Keppends, Arno (8); Van Roozendael, Michel (8); Verberne, Koen (9) - 1: Istituto di Fisica Applicata Nello Carrara del Consiglio Nazionale delle Ricerche (IFAC-CNR); Italy; 2: Epsilon International SA; 3: Science and Technology B.V.; 4: Finnish Meteorological Institute (FMI); 5: Royal Netherlands Meteorological Institute (KNMI); 6: Flyby, S.r.l.; 7: European Centre for Medium-rangeWeather Forecasts, Reading (ECMWF); 8: Royal Belgian Institute for Space Aeronomy (BIRA-IASB); 9: Datacraft
Synergistic exploitation of simultaneous and independent measurements of atmospheric composition acquired by future mission Sentinel-4 and Sentinel-5, as well as from the Sentinel-5 precursor already launched on October 13th, 2017, is the focus of the AURORA (Advanced Ultraviolet Radiation and Ozone Retrieval for Application) study, a three year project funded by the Horizon 2020 framework program of the European Union.
AURORA investigates the potential of a novel approach for the combination of complementary information from multiple sources about atmospheric Ozone vertical distribution from the surface to the top of the atmosphere and for subsequent calculation of associated products, such as tropospheric partial columns and ultraviolet surface radiation. For the first time to our knowledge, the study examines the outcome of Data Assimilation Systems ingesting Ozone vertical profiles obtained by applying an innovative a posteriori data fusion method, the so called Complete Data Fusion, to synthetic datasets simulating the operational retrieval products expected from Low Earth Orbit and Geostationary Orbit measurements of the atmospheric Sentinels missions of the Copernicus Program.
First results from a series of assimilation experiments, which according to the AURORA plans are executed using the TM5 and the IFS data assimilation systems and adopting an incremental approach, are now available. The presentation will provide a synthetic summary of the AURORA activities and will be focusing on the results of the comparison between the assimilation of fused data and the assimilation of standard retrieval products from observations of a virtual atmospheric scenario, as resulting from the outcome of assimilation experiments conducted with TM5.
The assimilation experiments, currently on-going with TM5 and IFS data assimilation system, are including a run for assimilation of standard Ozone profiles retrieved from measurements by TEMPO (Tropospheric Emission Monitoring of Pollution) over North America and by GEMS (Geostationary Environment Monitoring Spectrometer) over Asia-Pacific. This is to check the impact of air mases outside the geographical coverage of Sentinel-4 onto the outcome of the assimilation systems.
We will be finally reporting the preliminary results will also be reported of the key aspect of the project aimed to link the scientific achievements of the AURORA study to applications and services. Examples of applications capable to use the advanced quality data for tropospheric Ozone and ultraviolet radiation at the surface produced by AURORA will be presented in some details.
Exploring synergistic tools from NASA Satellite Data for Air Quality
Wei, Jennifer (1); Boller, Ryan (2); Zeng, Jian (1,3); Johnson, James (1,3); Meyer, David (1) - 1: NASA GSFC GES DISC, USA; 2: NASA GSFC, USA; 3: Adnet Systems Inc., USA
Space-borne earth observation has been important to monitor the earth condition and played a critical role in validating other instruments or modeling’s outputs. However, the data from satellite earth observation are usually very complex in terms of science contents, formats, and spatiotemporal granularities, making them difficult to use from many aspects. NASA Goddard Earth Sciences Data and Information Services Center (GES DISC), one of the 12 official NASA data centers, archives and distributes rich collections of data from multiple satellite missions and model results. The GES DISC is also the official archive center for data from the Ozone Monitoring Instrument (OMI) aboard NASA's Aura mission since 2004. Recently, the GES DISC has been evolving and improving its data management and services in order to promote NASA data to be easily discovered and accessed, as well as to facilitate interoperability. We’ll show in this presentation how to explore and analyze NASA earth observation data for air quality through a suite of user-friendly tools - from Worldview to Giovanni, demonstrating in using this set of tools prepares us to serve the Sentinel 5P TROPOMI to the community.
16:40 - 18:15
Retscher, Christian - ESA/ESRIN, Italy
Session Summaries and Reccomendations