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1. Transmission Spectroscopy with the ACE-FTS Infrared Spectral Atlas of Earth: A Model Validation and Feasibility Study

Author

Schreier, Franz, Städt, Steffen, Hedelt, Pascal, and Godolt, Mareike

Subjects
Astrophysics - Earth and Planetary Astrophysics
Abstract

Infrared solar occultation measurements are well established for remote sensing of Earth's atmosphere, and the corresponding primary transit spectroscopy has turned out to be valuable for characterization of extrasolar planets. Our objective is an assessment of the detectability of molecular signatures in Earth's transit spectra. To this end, we take a limb sequence of representative cloud-free transmission spectra recorded by the space-borne ACE-FTS Earth observation mission (Hughes et al., ACE infrared spectral atlases of the Earth's atmosphere, JQSRT 2014) and combine these spectra to the effective height of the atmosphere. These data are compared to spectra modeled with an atmospheric radiative transfer line-by-line infrared code to study the impact of individual molecules, spectral resolution, the choice of auxiliary data, and numerical approximations. Moreover, the study serves as a validation of our infrared radiative transfer code. The largest impact 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 best matching model has a mean residuum of 0.4 km and a maximum difference of 2 km to the measured effective height. For a quantitative estimate of visibility and detectability we consider the maximum change of the residual spectrum, the relative change of the residual norm, the additional transit depth, and signal-to-noise ratios for a JWST setup. In conclusion, our study provides a list of molecules that are relevant for modeling transmission spectra of Earth-like exoplanets and discusses the feasibility of retrieval., Comment: 25 pages, 15 figures, 3 tables

Published
2018
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2. An advanced spatial coregistration of cloud properties for the atmospheric Sentinel missions: application to TROPOMI.

Author

Argyrouli, Athina, Loyola, Diego, Romahn, Fabian, Lutz, Ronny, Molina García, Víctor, Hedelt, Pascal, Heue, Klaus-Peter, and Siddans, Richard

Subjects
REFLECTANCE measurement, METEOROLOGICAL satellites, INFRARED imaging, INFORMATION retrieval, ORBITS (Astronomy), ALBEDO
Abstract

The retrieval of cloud parameters from the atmospheric Sentinel missions requires Earth reflectance measurements from a set of spectral bands. The ground pixels of the involved spectral bands should be fully aligned, but when they are not, special treatment is required within the operational algorithms. This so-called inter-band spatial misregistration of passive spectrometers is present when the Earth reflectance measurements in different spectral bands are captured by different spectrometers. The cloud retrieval algorithm requires reflectance measurements in the UV(ultraviolet)–VIS (visible) band, where the first cloud parameter (i.e., radiometric cloud fraction) is retrieved from OCRA (Optical Cloud Recognition Algorithm). In addition, Earth reflectances in the NIR (near-infrared) band are needed for the retrieval of two additional cloud parameters (i.e., cloud height and cloud albedo or cloud-top height and optical thickness) from the ROCINN (Retrieval of Cloud Information using Neural Networks) algorithm. In the former TROPOMI (TROPOspheric Monitoring Instrument)/S5P (Sentinel-5 Precursor) retrieval, a coregistration scheme of the derived cloud parameters from the source band to the target band based on pre-calculated mapping weights from UV–VIS to NIR and vice versa is applied. In this paper we present a new scheme for the coregistration of the TROPOMI cloud parameters using collocated VIIRS (Visible Infrared Imaging Radiometer Suite)/SNPP (Suomi National Polar-orbiting Partnership) information. The new coregistration scheme based on the VIIRS data improves the TROPOMI cloud product quality and allows the addition of cloud information for the first (westernmost) TROPOMI UVIS ground pixel. In practice, the latter means that a significant number of valid data points are included in the TROPOMI cloud, total ozone, SO2 and HCHO product since 26 November 2023 (orbit 31705), when the new coregistration scheme became operational. From a comparison analysis between the two techniques, we found that the largest differences mainly appear for inhomogeneous scenes. From a validation exercise of TROPOMI against VIIRS in the across-track direction, we found that the old coregistration scheme tends to smooth out cloud structures along the scan line, whereas such structures can be maintained with the new scheme. The need to implement a similar inter-band spatial coregistration scheme is foreseen for the Sentinel-4/MTG-S (Meteosat Third Generation – Sounder) and Sentinel-5/MetOp-SG (Meteorological Operational Satellite – Second Generation) missions. In the case of the Sentinel-4 instrument, the external cloud information will originate from collocated data captured by the FCI (Flexible Combined Imager) on board the MTG-I (Meteosat Third Generation – Imager) satellite. [ABSTRACT FROM AUTHOR]

Published
2024
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3. Tropospheric NO2 retrieval algorithm for geostationary satellite instruments: applications to GEMS.

Author

Seo, Sora, Valks, Pieter, Lutz, Ronny, Heue, Klaus-Peter, Hedelt, Pascal, Molina García, Víctor, Loyola, Diego, Lee, Hanlim, and Kim, Jhoon

Subjects
GEOSTATIONARY satellites, STRATOSPHERIC chemistry, AIR masses, NITROGEN dioxide, SPATIAL resolution
Abstract

In this study, we develop an advanced retrieval algorithm for tropospheric nitrogen dioxide (NO2) from the geostationary satellite instruments and apply it to Geostationary Environment Monitoring Spectrometer (GEMS) observations. Overall, the algorithm follows previous heritage for the polar-orbiting satellites Global Ozone Monitoring Experiment-2 (GOME-2) and Tropospheric Monitoring Instrument (TROPOMI), but several improvements are implemented to account for specific features of geostationary satellites. The DLR GEMS NO2 retrieval employs an extended fitting window compared to the current fitting window used in GEMS operational v2.0 NO2 retrieval, which results in improved spectral fit quality and lower uncertainties. For the stratosphere–troposphere separation in GEMS measurements, two methods are developed and evaluated: (1) STRatospheric Estimation Algorithm from Mainz (STREAM) as used in the DLR TROPOMI NO2 retrieval and adapted to GEMS and (2) estimation of stratospheric NO2 columns from the Copernicus Atmosphere Monitoring Service (CAMS) Integrated Forecast System (IFS) cycle 48R1 model data, which introduce full stratospheric chemistry as it will be used in the operational Sentinel-4 NO2 retrieval. While STREAM provides hourly estimates of stratospheric NO2, it has limitations in describing small-scale variations and exhibits systematic biases near the boundary of the field of view. In this respect, the use of estimated stratospheric NO2 columns from the CAMS forecast model profile demonstrates better applicability by describing not only diurnal variation but also small-scale variations. For the improved air mass factor (AMF) calculation, sensitivity tests are performed using different input data. In our algorithm, cloud fractions retrieved from the Optical Cloud Recognition Algorithm (OCRA) adapted to GEMS level 1 data are applied instead of the GEMS v2.0 cloud fraction. OCRA is used operationally in TROPOMI and Sentinel-4. Compared to the GEMS level 2 cloud fraction which is typically set to around 0.1 for clear-sky scenes, OCRA sets cloud fractions close to or at 0. The OCRA-based cloud corrections result in increased tropospheric AMFs and decreased tropospheric NO2 vertical columns, leading to better agreement with results from existing TROPOMI observations. The effects of surface albedo on GEMS tropospheric NO2 retrievals are assessed by comparing the GEMS v2.0 background surface reflectance (BSR) and TROPOMI Lambertian-equivalent reflectivity (LER) climatology v2.0 product. The differences between the two surface albedo products and their impact on tropospheric AMF are particularly pronounced over snow/ice scenes during winter. A priori NO2 profiles from the CAMS forecast model, applied in the DLR GEMS algorithm, effectively capture variations in NO2 concentrations throughout the day with high spatial resolution and the advanced chemical mechanism, which demonstrates its suitability for geostationary satellite measurements. The retrieved DLR GEMS tropospheric NO2 columns show good capability for capturing hotspot signals at the scale of city clusters and describe spatial gradients from city centres to surrounding areas. Diurnal variations of tropospheric NO2 columns over Asia are well described through hourly sampling of GEMS. Evaluation of DLR GEMS tropospheric NO2 columns against TROPOMI v2.4 and GEMS v2.0 operational products shows overall good agreement. The uncertainty of DLR GEMS tropospheric NO2 vertical columns varies based on observation scenarios. In regions with low pollution levels such as open-ocean and remote rural areas, retrieval uncertainties typically range from 10 % to 50 %, primarily due to uncertainties in slant columns. For heavily polluted regions, uncertainties in tropospheric NO2 columns are mainly driven by errors in tropospheric AMF calculations. Notably, the total uncertainty in GEMS tropospheric NO2 columns is most significant in winter, particularly over heavily polluted regions with low-level clouds below or near the NO2 peak. [ABSTRACT FROM AUTHOR]

Published
2024
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6. Advanced retrieval of sulfur dioxide from TROPOMI using COBRA

Author

Theys, Nicolas, primary, Vlietinck, Jonas, additional, Yu, Huan, additional, De Smedt, Isabelle, additional, Fabris, Lorenzo, additional, Brenot, Hugues, additional, van Gent, Jeroen, additional, Niemeijer, Sander, additional, Romahn, Fabian, additional, Hedelt, Pascal, additional, Loyola, Diego, additional, and Van Roozendael, Michel, additional

Published
2024
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7. The Earth as an extrasolar transiting planet - II: HARPS and UVES detection of water vapor, biogenic O$_2$, and O$_3$

Author

Arnold, Luc, Ehrenreich, David, Vidal-Madjar, Alfred, Dumusque, Xavier, Nitschelm, Christian, Querel, Richard R., Hedelt, Pascal, Berthier, Jérôme, Lovis, Christophe, Moutou, Claire, Ferlet, Roger, and Crooker, David

Subjects
Astrophysics - Earth and Planetary Astrophysics
Abstract

The atmospheric composition of transiting exoplanets can be characterized during transit by spectroscopy. For the transit of an Earth twin, models predict that biogenic $O_2$ and $O_3$ should be detectable, as well as water vapour, a molecule linked to habitability as we know it on Earth. The aim is to measure the Earth radius versus wavelength $\lambda$ - or the atmosphere thickness $h(\lambda)$ - at the highest spectral resolution available to fully characterize the signature of Earth seen as a transiting exoplanet. We present observations of the Moon eclipse of 21-12-2010. Seen from the Moon, the Earth eclipses the Sun and opens access to the Earth atmosphere transmission spectrum. We used HARPS and UVES spectrographs to take penumbra and umbra high-resolution spectra from 3100 to 10400 Ang. A change of the quantity of water vapour above the telescope compromised the quality of the UVES data. We corrected for this effect in the data processing. We analyzed the data by 3 different methods. The 1st method is based on the analysis of pairs of penumbra spectra. The 2nd makes use of a single penumbra spectrum, and the 3rd of all penumbra and umbra spectra. Profiles $h(\lambda)$ are obtained with the three methods for both instruments. The 1st method gives the best result, in agreement with a model. The second method seems to be more sensitive to the Doppler shift of solar spectral lines with respect to the telluric lines. The 3rd method makes use of umbra spectra which bias the result, but it can be corrected for this a posteriori from results with the first method. The 3 methods clearly show the spectral signature of the Rayleigh scattering in the Earth atmosphere and the bands of H$_2$O, O$_2$, and O$_3$. Sodium is detected. Assuming no atmospheric perturbations, we show that the E-ELT is theoretically able to detect the $O_2$ A-band in 8~h of integration for an Earth twin at 10pc., Comment: Final version accepted for publication in A&A - 21 pages, 27 figures. Abstract above slightly shortened wrt the original. The ArXiv version has low resolution figures, but a version with full resolution figures is available here: http://www.obs-hp.fr/~larnold/publi_to_download/eclipse2010_AA_v5_final.pdf

Published
2014
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8. Global Ozone Monitoring Experiment-2 (GOME-2) daily and monthly level-3 products of atmospheric trace gas columns

Author

Environment Research and Technology Development Fund, Japan Society for the Promotion of Science, Ministry of Education, Culture, Sports, Science and Technology (Japan), #NODATA#, Heue, Klaus Peter [0000-0001-8823-7712], Hedelt, Pascal [0000-0002-1752-0040], Loyola, Diego [0000-0002-8547-9350], Pinardi, Gaia [0000-0001-5428-916X], Kumar, Vinod [0000-0002-8405-3470], Bais, Alkis [0000-0003-3899-2001], Takashima, Hisahiro [0000-0001-5267-0792], Frieß, Udo [0000-0001-7176-7936], Richter, Andreas [0000-0003-3339-212X], Ma, Jianzhong [0000-0002-9510-5432], Holla, Robert [0000-0002-6445-9510], Postylyakov, Oleg [0000-0003-4202-1945], Rivera Cárdenas, Claudia [0000-0002-8617-265X], Wenig, Mark [0000-0002-9255-083X], Chan, Ka Lok, Valks, Pieter, Heue, Klaus Peter, Lutz, Ronny, Hedelt, Pascal, Loyola, Diego, Pinardi, Gaia, Van Roozendael, Michel, Hendrick, François, Wagner, Thomas, Kumar, Vinod, Bais, Alkis, Piters, Ankie, Irie, Hitoshi, Takashima, Hisahiro, Kanaya, Yugo, Choi, Yongjoo, Park, Kihong, Chong, Jihyo, Cede, Alexander, Frieß, Udo, Richter, Andreas, Ma, Jianzhong, Benavent, Nuria, Holla, Robert, Postylyakov, Oleg, Rivera Cárdenas, Claudia, Wenig, Mark, Environment Research and Technology Development Fund, Japan Society for the Promotion of Science, Ministry of Education, Culture, Sports, Science and Technology (Japan), #NODATA#, Heue, Klaus Peter [0000-0001-8823-7712], Hedelt, Pascal [0000-0002-1752-0040], Loyola, Diego [0000-0002-8547-9350], Pinardi, Gaia [0000-0001-5428-916X], Kumar, Vinod [0000-0002-8405-3470], Bais, Alkis [0000-0003-3899-2001], Takashima, Hisahiro [0000-0001-5267-0792], Frieß, Udo [0000-0001-7176-7936], Richter, Andreas [0000-0003-3339-212X], Ma, Jianzhong [0000-0002-9510-5432], Holla, Robert [0000-0002-6445-9510], Postylyakov, Oleg [0000-0003-4202-1945], Rivera Cárdenas, Claudia [0000-0002-8617-265X], Wenig, Mark [0000-0002-9255-083X], Chan, Ka Lok, Valks, Pieter, Heue, Klaus Peter, Lutz, Ronny, Hedelt, Pascal, Loyola, Diego, Pinardi, Gaia, Van Roozendael, Michel, Hendrick, François, Wagner, Thomas, Kumar, Vinod, Bais, Alkis, Piters, Ankie, Irie, Hitoshi, Takashima, Hisahiro, Kanaya, Yugo, Choi, Yongjoo, Park, Kihong, Chong, Jihyo, Cede, Alexander, Frieß, Udo, Richter, Andreas, Ma, Jianzhong, Benavent, Nuria, Holla, Robert, Postylyakov, Oleg, Rivera Cárdenas, Claudia, and Wenig, Mark

Abstract

We introduce the new Global Ozone Monitoring Experiment-2 (GOME-2) daily and monthly level-3 product of total column ozone (O3), total and tropospheric column nitrogen dioxide (NO2), total column water vapour, total column bromine oxide (BrO), total column formaldehyde (HCHO), and total column sulfur dioxide (SO2) (daily products 10.15770/EUM-SAF-AC-0048, ; monthly products 10.15770/EUM-SAF-AC-0049, ). The GOME-2 level-3 products aim to provide easily translatable and user-friendly data sets to the scientific community for scientific progress as well as to satisfy public interest. The purpose of this paper is to present the theoretical basis as well as the verification and validation of the GOME-2 daily and monthly level-3 products. The GOME-2 level-3 products are produced using the overlapping area-weighting method. Details of the gridding algorithm are presented. The spatial resolution of the GOME-2 level-3 products is selected based on the sensitivity study. The consistency of the resulting level-3 products among three GOME-2 sensors is investigated through time series of global averages, zonal averages, and bias. The accuracy of the products is validated by comparison to ground-based observations. The verification and validation results show that the GOME-2 level-3 products are consistent with the level-2 data. Small discrepancies are found among three GOME-2 sensors, which are mainly caused by the differences in the instrument characteristic and level-2 processor. The comparison of GOME-2 level-3 products to ground-based observations in general shows very good agreement, indicating that the products are consistent and fulfil the requirements to serve the scientific community and general public.

Published
2023

9. Spectral features of Earth-like planets and their detectability at different orbital distances around F, G, and K-type stars

Author

Hedelt, Pascal, von Paris, Philip, Godolt, Mareike, Gebauer, Stefanie, Grenfell, John Lee, Rauer, Heike, Schreier, Franz, Selsis, Franck, and Trautmann, Thomas

Subjects
Astrophysics - Earth and Planetary Astrophysics
Abstract

We investigate the spectral appearance of Earth-like exoplanets in the HZ of different main sequence stars at different orbital distances. We furthermore discuss for which of these scenarios biomarker absorption bands may be detected during primary or secondary transit with near-future telescopes and instruments.We analyze the spectra taking into account different filter bandpasses of two photometric instruments planned to be mounted to the JWST. We analyze in which filters and for which scenarios molecular absorption bands are detectable when using the space-borne JWST or the ground-based telescope E-ELT. Absorption bands of CO2, H2O, CH4 and O3 are clearly visible in high-resolution spectra as well as in the filters of photometric instruments. However, only during primary eclipse bands of CO2, H2O and O3 are detectable for all scenarios when using photometric instruments and an E-ELT telescope setup. CH4 is only detectable at the outer HZ of the K star since here the atmospheric modeling results in very high abundances. Since the detectable CO2 and H2O bands overlap, separate bands need to be observed to prove their existence in the atmosphere. In order to detect H2O in a separate band, a S/N>7 needs to be achieved for E-ELT observations, e.g. by co-adding at least 10 transit observations. Using a spaceborne telescope like the JWST enables the detection of CO2 at 4.3mu, which is not possible for ground-based observations due to the Earth's atmospheric absorption. Hence combining observations of spaceborne and groundbased telescopes might allow to detect the presence of the biomarker molecule O3 and the related compounds H2O and CO2 in a planetary atmosphere. Other absorption bands using the JWST can only be detected for much higher S/Ns, which is not achievable by just co-adding transit observations since this would be far beyond the planned mission time of JWST.(abridged), Comment: 15 pages, 8 figures

Published
2013
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10. Atmospheric constraints for the CO2 partial pressure on terrestrial planets near the outer edge of the habitable zone

Author

von Paris, Philip, Grenfell, J. Lee, Hedelt, Pascal, Rauer, Heike, Selsis, Franck, and Stracke, Barbara

Subjects
Astrophysics - Earth and Planetary Astrophysics
Abstract

In recent years, several potentially habitable, probably terrestrial exoplanets and exoplanet candidates have been discovered. The amount of CO2 in their atmosphere is of great importance for surface conditions and habitability. In the absence of detailed information on the geochemistry of the planet, this amount could be considered as a free parameter. Up to now, CO2 partial pressures for terrestrial planets have been obtained assuming an available volatile reservoir and outgassing scenarios. This study aims at calculating the allowed maximum CO2 pressure at the surface of terrestrial exoplanets orbiting near the outer boundary of the habitable zone by coupling the radiative effects of the CO2 and its condensation at the surface. These constraints might limit the permitted amount of atmospheric CO2, independent of the planetary reservoir. A 1D radiative-convective cloud-free atmospheric model was used. CO2 partial pressures are fixed according to surface temperature and vapor pressure curve. Considered scenarios cover a wide range of parameters. Results show that for planets in the habitable zone around K-, G-, and F-type stars the allowed CO2 pressure is limited by the vapor pressure curve and not by the planetary reservoir. The maximum CO2 pressure lies below the CO2 vapor pressure at the critical point of pcrit =73.8 bar. For M-type stars, CO2 pressures above pcrit are possible for almost all scenarios considered across the habitable zone. This implies that determining CO2 partial pressures for terrestrial planets by using only geological models is probably too simplified and might over-estimate atmospheric CO2 towards the outer edge of the habitable zone. (abridged), Comment: accepted to Astronomy&Astrophysics, 9 pages, 9 figures, 1 table

Published
2012
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11. Spectroscopic characterization of the atmospheres of potentially habitable planets: GL 581 d as a model case study

Author

von Paris, Philip, Cabrera, Juan, Godolt, Mareike, Grenfell, J. Lee, Hedelt, Pascal, Rauer, Heike, Schreier, Franz, and Stracke, Barbara

Subjects
Astrophysics - Earth and Planetary Astrophysics
Abstract

(abridged) The Super-Earth candidate GL 581 d is the first potentially habitable extrasolar planet. Therefore, GL 581 d is used to illustrate a hypothetical detailed spectroscopic characterization of such planets. Atmospheric profiles from 1D radiative-convective model scenarios of GL 581 d were used to calculate high-resolution synthetic spectra. From the spectra, signal-to-noise ratios were calculated for a telescope such as the planned James Webb Space Telescope. The presence of the model atmospheres could be clearly inferred from the calculated synthetic spectra due to strong water and carbon dioxide absorption bands. Surface temperatures could be inferred for model scenarios with optically thin spectral windows. Dense, CO2-rich scenarios did not allow for the characterization of surface temperatures and to assess habitability. Degeneracies between CO2 concentration and surface pressure further complicated the interpretation of the calculated spectra, hence the determination of atmospheric conditions. Still, inferring approximative CO2 concentrations and surface pressures would be possible. In practice, detecting atmospheric signals is challenging. The SNR for a single transit was only larger than unity in some near-IR bands for transmission spectroscopy. Most interestingly, the false-positive detection of biomarker candidates such as methane and ozone could be possible in low resolution spectra due to the presence of CO2 absorption bands which overlap with biomarker spectral bands. This can be avoided however by observing all main CO2 IR bands instead of concentrating on, e.g., the 4.3 or 15 micron bands only. Furthermore, a masking of ozone signatures by CO2 absorption bands is shown to be possible. Simulations imply that such a false-negative detection of ozone would be possible even for rather large ozone concentrations of up to 1E-5., Comment: accepted in Astronomy and Astrophysics, 14 pages, 12 figures, 3 tables

Published
2011
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12. Sensitivity of Biomarkers to Changes in Chemical Emissions in the Earth's Proterozoic Atmosphere

Author

Grenfell, John Lee, Gebauer, Stefanie, von Paris, Philip, Godolt, Mareike, Hedelt, Pascal, Patzer, Beate, Stracke, Barbara, and Rauer, Heike

Subjects
Astrophysics - Earth and Planetary Astrophysics
Abstract

The search for life beyond the Solar System is a major activity in exoplanet science. However, even if an Earth-like planet were to be found, it is unlikely to be at a similar stage of evolution as the modern Earth. It is therefore of interest to investigate the sensitivity of biomarker signals for life as we know it for an Earth-like planet but at earlier stages of evolution. Here, we assess biomarkers i.e. species almost exclusively associated with life, in present-day and in 10% present atmospheric level oxygen atmospheres corresponding to the Earth's Proterozoic period. We investigate the impact of proposed enhanced microbial emissions of the biomarker nitrous oxide, which photolyses to form nitrogen oxides which can destroy the biomarker ozone. A major result of our work is regardless of the microbial activity producing nitrous oxide in the early anoxic ocean, a certain minimum ozone column can be expected to persist in Proterozoic-type atmospheres due to a stabilising feedback loop between ozone, nitrous oxide and the ultraviolet radiation field. Atmospheric nitrous oxide columns were enhanced by a factor of 51 for the Proterozoic "Canfield ocean" scenario with 100 times increased nitrous oxide surface emissions. In such a scenario nitrous oxide displays prominent spectral features, so may be more important as a biomarker than previously considered in such cases. The run with "Canfield ocean" nitrous oxide emissions enhanced by a factor of 100 also featured additional surface warming of 3.5K. Our results suggest that the Proterozoic ozone layer mostly survives the changes in composition which implies that it is indeed a good atmospheric biomarker., Comment: 27 pages, 5 Figures, 4 Tables

Published
2010
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13. An advanced spatial co-registration of cloud properties for the atmospheric Sentinel missions: Application to TROPOMI.

Author

Argyrouli, Athina, Loyola, Diego, Romahn, Fabian, Lutz, Ronny, García, Víctor Molina, Hedelt, Pascal, Heue, Klaus-Peter, and Siddans, Richard

Subjects
REFLECTANCE measurement, ALBEDO, METEOROLOGICAL satellites, INFRARED imaging, SPECTRAL imaging, INFORMATION retrieval, ORBITS (Astronomy)
Abstract

The retrieval of cloud parameters from the atmospheric Sentinel missions require Earth reflectance measurements from a set of spectral bands. Frequently, the ground pixel footprints of the involved spectral bands are not fully aligned and therefore, special treatment is required within the operational algorithms. This so-called inter-band spatial mis-registration of passive spectrometers is present when the Earth reflectance measurements in different spectral bands are captured by different spectrometers. The cloud retrieval algorithm requires reflectance measurements in the UV (ultraviolet)/VIS (visible) band, where the first cloud parameter (i.e., radiometric cloud fraction) is retrieved from the OCRA (Optical Cloud Recognition Algorithm) algorithm. In addition, Earth reflectances in the NIR (near-infrared) band are needed for the retrieval of two additional cloud parameters (i.e., cloud height and cloud albedo or cloud-top height and optical thickness) from the ROCINN (Retrieval of Cloud Information using Neural Networks) algorithm. In the former TROPOMI (TROPOspheric Monitoring Instrument)/S5P (Sentinel-5 Precursor) retrieval, a co-registration scheme of the derived cloud parameters from the source band to the target band based on pre-calculated mapping weights from UV/VIS to NIR, and vice versa, is applied. In this paper we present a new scheme for the co-registration of the TROPOMI cloud parameters using collocated VIIRS (Visible Infrared Imaging Radiometer Suite)/SNPP (Suomi National Polar-orbiting Partnership) information. A great benefit of the new co-registration scheme based on the VIIRS data is that it improves the overall quality of the TROPOMI cloud products and, in addition, it allows the re-construction of the cloud parameters on the first UV/VIS detector pixel, which was impossible with the former scheme based on the static mapping tables. The latter practically means that a significant number of valid data points are added to the TROPOMI cloud, total ozone, SO2 and HCHO product since November 26th 2023 (orbit 31705), when the UPAS version 2.6 with the new co-registration scheme was activated operationally. From a comparison analysis between the two techniques, we found that the largest differences mainly appear for inhomogeneous scenes. From a validation exercise of TROPOMI against VIIRS in the across-track flight direction, we found that the old co-registration scheme tends to smooth out cloud structures along the scanline, whereas such structures can be maintained with the new scheme. The need to implement a similar inter-band spatial co-registration scheme is foreseen for the Sentinel-4/MTG-S (Meteosat Third Generation - Sounder) and Sentinel-5/MetOp-SG (Meteorological Operational Satellite - Second Generation) missions. In the case of Sentinel-4 instrument, the external cloud information will originate from collocated FCI (Flexible Combined Imager) data, on board the MTG-I (Meteosat Third Generation - Imager) satellite. [ABSTRACT FROM AUTHOR]

Published
2024
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14. Emissions of Sulphur Dioxide (SO2) from Coal-Fired Power Plants in Serbia and Bosnia-Herzegovina: First Attempts of a Validation of TROPOMI Satellite Products with Airborne In Situ Measurements

Author

Huntrieser, Heidi, primary, Klausner-Harlaß, Theresa, primary, Aufmhoff, Heinfried, primary, Baumann, Robert, primary, Fiehn, Alina, primary, Hedelt, Pascal, primary, Gottschaldt, Klaus-Dirk, primary, Lutz, Ronny, primary, Mrazovac Kurilić, Sanja, primary, Podraščanin, Zorica, primary, Ilić, Predrag, primary, Theys, Nicolas, primary, Jöckel, Patrick, primary, Loyola, Diego, primary, Makroum, Ismail, primary, Mertens, Mariano, primary, and Roiger, Anke, primary

Published
2023
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16. Global Ozone Monitoring Experiment-2 (GOME-2) Daily and Monthly Level 3 Products of Atmospheric Trace Gas Columns

Author

Chan, Ka Lok, primary, Valks, Pieter, additional, Heue, Klaus-Peter, additional, Lutz, Ronny, additional, Hedelt, Pascal, additional, Loyola, Diego, additional, Pinardi, Gaia, additional, Van Roozendael, Michel, additional, Hendrick, François, additional, Wagner, Thomas, additional, Kumar, Vinod, additional, Bais, Alkis, additional, Piters, Ankie, additional, Irie, Hitoshi, additional, Kanaya, Yugo, additional, Takashima, Hisahiro, additional, Choi, Yongjoo, additional, Park, Kihong, additional, Chong, Jihyo, additional, Cede, Alexander, additional, Frieß, Udo, additional, Richter, Andreas, additional, Ma, Jianzhong, additional, Benavent, Nuria, additional, Holla, Robert, additional, Postylyakov, Oleg, additional, Rivera Cárdenas, Claudia, additional, and Wenig, Mark, additional

Published
2022
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19. Volcanic SO2layer height by TROPOMI/S5P: evaluation against IASI/MetOp and CALIOP/CALIPSO observations

Author

Koukouli, M., Michailidis, Konstantinos, Hedelt, Pascal, Taylor, Isabelle I.A., Inness, Antje, Clarisse, Lieven, Balis, Dimitris, Efremenko, Dmitry D.S., Loyola, Diego, Grainger, Roy Gordon, Retscher, Christian, Koukouli, M., Michailidis, Konstantinos, Hedelt, Pascal, Taylor, Isabelle I.A., Inness, Antje, Clarisse, Lieven, Balis, Dimitris, Efremenko, Dmitry D.S., Loyola, Diego, Grainger, Roy Gordon, and Retscher, Christian

Abstract

Volcanic eruptions eject large amounts of ash and trace gases such as sulfur dioxide (SO2) into the atmosphere. A significant difficulty in mitigating the impact of volcanic SO2 clouds on air traffic safety is that these gas emissions can be rapidly transported over long distances. The use of space-borne instruments enables the global monitoring of volcanic SO2 emissions in an economical and risk-free manner. Within the European Space Agency (ESA) Sentinel-5p+ Innovation project, the S5P SO2 layer height (S5P+I: SO2LH) activities led to the improvements of the retrieval algorithm and generation of the corresponding near real-time S5P SO2 LH products. These are currently operationally provided, in near real-time, by the German Aerospace Center (DLR) within the framework of the Innovative Products for Analyses of Atmospheric Composition (INPULS) project. The main aim of this paper is to present its extensive verification, accomplished within the S5P+I: SO2LH project, over major recent volcanic eruptions, against collocated space-borne measurements from the IASI/Metop and CALIOP/CALIPSO instruments as well as assess its impact on the forecasts provided by the Copernicus Atmospheric Monitoring Service (CAMS). The mean difference between S5P and IASI observations for the Raikoke 2019, the Nishinoshima 2020 and the La Soufrière-St Vincent 2021 eruptive periods is g-1/4 0.5 ± 3 km, while for the Taal 2020 eruption, a larger difference was found, between 3 ± 3 km and 4 ± 3 km. The comparison of the daily mean SO2 LH further demonstrates the capabilities of this near real-time product, with slopes between 0.8 and 1 and correlation coefficients ranging between 0.6 and 0.8. Comparisons between the S5P SO2 LH and the CALIOP/CALIPSO ash plumes revealed an expected bias at -2.5 ± 2 km, considering that the injected SO2 and ash plume locations do not always coincide over an eruption. Furthermore, the CAMS assimilation of the S5P SO2 LH product led to much improved model output aga, SCOPUS: ar.j, info:eu-repo/semantics/published

Published
2022

20. Global Ozone Monitoring Experiment-2 (GOME-2) daily and monthly level-3 products of atmospheric trace gas columns.

Author

Chan, Ka Lok, Valks, Pieter, Heue, Klaus-Peter, Lutz, Ronny, Hedelt, Pascal, Loyola, Diego, Pinardi, Gaia, Van Roozendael, Michel, Hendrick, François, Wagner, Thomas, Kumar, Vinod, Bais, Alkis, Piters, Ankie, Irie, Hitoshi, Takashima, Hisahiro, Kanaya, Yugo, Choi, Yongjoo, Park, Kihong, Chong, Jihyo, and Cede, Alexander

Subjects
TRACE gases, OZONE, AIR pollutants, WATER vapor, TROPOSPHERIC ozone, NITROGEN dioxide, SCIENTIFIC community
Abstract

We introduce the new Global Ozone Monitoring Experiment-2 (GOME-2) daily and monthly level-3 product of total column ozone (O 3), total and tropospheric column nitrogen dioxide (NO 2), total column water vapour, total column bromine oxide (BrO), total column formaldehyde (HCHO), and total column sulfur dioxide (SO 2) (daily products 10.15770/EUM_SAF_AC_0048, ; monthly products 10.15770/EUM_SAF_AC_0049,). The GOME-2 level-3 products aim to provide easily translatable and user-friendly data sets to the scientific community for scientific progress as well as to satisfy public interest. The purpose of this paper is to present the theoretical basis as well as the verification and validation of the GOME-2 daily and monthly level-3 products. The GOME-2 level-3 products are produced using the overlapping area-weighting method. Details of the gridding algorithm are presented. The spatial resolution of the GOME-2 level-3 products is selected based on the sensitivity study. The consistency of the resulting level-3 products among three GOME-2 sensors is investigated through time series of global averages, zonal averages, and bias. The accuracy of the products is validated by comparison to ground-based observations. The verification and validation results show that the GOME-2 level-3 products are consistent with the level-2 data. Small discrepancies are found among three GOME-2 sensors, which are mainly caused by the differences in the instrument characteristic and level-2 processor. The comparison of GOME-2 level-3 products to ground-based observations in general shows very good agreement, indicating that the products are consistent and fulfil the requirements to serve the scientific community and general public. [ABSTRACT FROM AUTHOR]

Published
2023
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25. Evaluating the assimilation of S5P/TROPOMI near real-time SO<sub>2</sub> columns and layer height data into the CAMS integrated forecasting system (CY47R1), based on a case study of the 2019 Raikoke eruption

Author

Inness, Antje, primary, Ades, Melanie, additional, Balis, Dimitris, additional, Efremenko, Dmitry, additional, Flemming, Johannes, additional, Hedelt, Pascal, additional, Koukouli, Maria-Elissavet, additional, Loyola, Diego, additional, and Ribas, Roberto, additional

Published
2022
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26. Volcanic SO2 Layer Height by TROPOMI/S5P; validation against IASI/MetOp and CALIOP/CALIPSO observations

Author

Koukouli, Maria-Elissavet, Michailidis, Konstantinos, Hedelt, Pascal, Taylor, Isabelle A., Inness, Antje, Clarisse, Lieven, Balis, Dimitris, Efremenko, Dmitry, Loyola, Diego, Grainger, Roy G., and Retscher, Christian

Abstract

Volcanic eruptions eject large amounts of ash and trace gases such as sulphur dioxide (SO2) into the atmosphere. A significant difficulty in mitigating the impact of volcanic SO2 clouds on air traffic safety is that these gas emissions can be rapidly transported over long distances. The use of space-borne instruments enables the global monitoring of volcanic SO2 emissions in an economical and risk-free manner. Within the European Space Agency (ESA) Sentinel-5p+ Innovation project, the S5P SO2 Layer Height (S5P+I: SO2 LH) activities led to the improvements on the retrieval algorithm and generation of the corresponding near-real-time S5P SO2 LH products. These are currently operationally provided, in near-real-time, by the German Aerospace Center (DLR) in the framework of the Innovative Products for Analyses of Atmospheric Composition, INPULS, project. The main aim of this paper is to present its extensive verification, accomplished within the S5P+I: SO2 LH project, over major recent volcanic eruptions, against collocated space-born measurements from the IASI/Metop and CALIOP/CALIPSO instruments, as well as assess its impact on the forecasts provided by the Copernicus Atmospheric Monitoring Service, CAMS. The mean difference between S5P and IASI observations for the Raikoke 2019, the Nishinoshima 2020 and the La Soufrière-St Vincent, 2021 eruptive periods is ~0.5 ± 3 km, while for the Taal 2020 eruption, a larger difference was found, between 3 and 4 ± 3 km. The comparison of the daily mean SO2 layer heights further demonstrates the capabilities of this near-real-time product, with slopes between 0.8 and 1 and correlations ranging between 0.6 and 0.8. Comparisons between the S5P+I: SO2 LH and the CALIOP/CALIPSO ash plume height are also satisfactory at −2.5 ± 2 km, considering that the injected SO2 and ash plumes’ locations do not always coincide over an eruption. Furthermore, the CAMS assimilation of the S5P+I: SO2 LH product led to much improved model output against the non-assimilated IASI layer heights, with a mean difference of 1.5 ± 2 km compared to the original CAMS analysis, and improved the geographical spread of the Raikoke volcanic plume following the eruptive days.

Published
2021

27. S5P+I SO2 Layer Height Product User Manual

Author

Hedelt, Pascal

Subjects
Sentinel-5 precursor, SO2 layer height, SO2, TROPOMI, Volcanic eruptions
Abstract

This Product User Manual (PUM) describes the technical characteristics of the S5p/TROPOMI SO2 LH L2 geophysical data product that is needed for efficient and correct use of the data contained and the structure of the L2 datafile is described. A description of the related retrieval SO2 layer height algorithm can be found in the S5P+I SO2LH ATBD.

Published
2021
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28. The CAMS volcanic forecasting system utilizing near-real time data assimilation of S5P/TROPOMI SO2 retrievals

Author

Inness, Antje, Ades, Melanie, Balis, Dimitris, Efremenko, Dmitry, Flemming, Johannes, Hedelt, Pascal, Koukouli, Maria-Elissavet, Loyola, Diego, and Ribas, Roberto

Abstract

The Copernicus Atmosphere Monitoring Service (CAMS), operated by the European Centre for Medium-Range Weather Forecasts on behalf of the European Commission, provides daily analyses and 5-day forecasts of atmospheric composition, including forecasts of volcanic sulphur dioxide (SO2) in near-real time. CAMS currently assimilates total column SO2 retrievals from the GOME-2 instruments on MetOp-B and -C and the TROPOMI instrument on Sentinel-5P which give information about the location and strength of volcanic plumes. However, the operational TROPOMI and GOME-2 retrievals do not provide any information about the height of the volcanic plumes and therefore some prior assumptions need to be made in the CAMS data assimilation system about where to place the resulting SO2 increments in the vertical. In the current operational CAMS configuration, the SO2 increments are placed in the mid-troposphere, around 550 hPa or 5 km. While this gives good results for the majority of volcanic emissions, it will clearly be wrong for eruptions that inject SO2 at very different altitudes, in particular exceptional events where part of the SO2 plume reaches the stratosphere. A new algorithm, developed by DLR for GOME-2 and TROPOMI and optimized in the frame of the ESA-funded Sentinel-5P Innovation–SO2 Layer Height Project, the Full-Physics Inverse Learning Machine (FP_ILM) algorithm, retrieves SO2 layer height from TROPOMI in NRT in addition to the SO2 column. CAMS is testing the assimilation of these data, making use of the NRT layer height information to place the SO2 increments at a retrieved altitude. Assimilation tests with the TROPOMI SO2 layer height data for the Raikoke eruption in June 2019 show that the resulting CAMS SO2 plume heights agree better with IASI plume height retrievals than operational CAMS runs without the TROPOMI SO2 layer height information and that making use of the additional layer height information leads to improved SO2 forecasts than when using the operational CAMS configuration. By assimilating the SO2 layer height data the CAMS system can predict the overall location of the Raikoke SO2 plume up to 5 days in advance for about 20 days after the initial eruption.

Published
2021

29. S5P+I SO2 Layer Height Validation Report

Author

Koukouli, Maria Elissavet, Michailidis, Konstantinos, Balis, and Hedelt, Pascal

Subjects
Sulfur dioxide, SO2 Layer Height, Volcanoes, TROPOMI
Abstract

This is the Validation Report describing the validation operations of the S5P+I SO2 Layer Height Level-2 products based on Sentinel-5P/TROPOMI measurements &nbsp

Published
2021
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30. Algorithm Theoretical Basis Document (ATBD) for the S5p+I: SO2 Layer Height product

Author

Hedelt, Pascal and Koukouli, Maria Elissavet

Subjects
Sentinel-5 precursor, SO2 Layer Height, Sulfur Dioxide, Radiative transfer, SO2, TROPOMI, Volcanic eruptions
Abstract

This is the Algorithm Theoretical Basis Document (ATBD) describing the theoretical basis and the implementation of the S5p+I SO2 Layer Height product from Sentinel-5P/TROPOMI measurements. The purpose of the document is to give detailed mathematical description of the algorithm and to discuss the necessary input and auxiliary data, and the output that will be generated. In addition, information about the expected size of the product, expected calculation times, and the expected accuracy are provided. The document is part of the ESA S5p+I SO2LH project. &nbsp

Published
2021
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32. Volcanic SO2 Layer Height by TROPOMI/S5P; validation against IASI/MetOp and CALIOP/CALIPSO observations

Author

Koukouli, Maria-Elissavet, primary, Michailidis, Konstantinos, additional, Hedelt, Pascal, additional, Taylor, Isabelle A., additional, Inness, Antje, additional, Clarisse, Lieven, additional, Balis, Dimitris, additional, Efremenko, Dmitry, additional, Loyola, Diego, additional, Grainger, Roy G., additional, and Retscher, Christian, additional

Published
2021
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33. Supplementary material to "Volcanic SO<sub>2</sub> Layer Height by TROPOMI/S5P; validation against IASI/MetOp and CALIOP/CALIPSO observations"

Author

Koukouli, Maria-Elissavet, primary, Michailidis, Konstantinos, additional, Hedelt, Pascal, additional, Taylor, Isabelle A., additional, Inness, Antje, additional, Clarisse, Lieven, additional, Balis, Dimitris, additional, Efremenko, Dmitry, additional, Loyola, Diego, additional, Grainger, Roy G., additional, and Retscher, Christian, additional

Published
2021
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34. A sulfur dioxide Covariance-Based Retrieval Algorithm (COBRA): application to TROPOMI reveals new emission sources

Author

Theys, Nicolas, primary, Fioletov, Vitali, additional, Li, Can, additional, De Smedt, Isabelle, additional, Lerot, Christophe, additional, McLinden, Chris, additional, Krotkov, Nickolay, additional, Griffin, Debora, additional, Clarisse, Lieven, additional, Hedelt, Pascal, additional, Loyola, Diego, additional, Wagner, Thomas, additional, Kumar, Vinod, additional, Innes, Antje, additional, Ribas, Roberto, additional, Hendrick, François, additional, Vlietinck, Jonas, additional, Brenot, Hugues, additional, and Van Roozendael, Michel, additional

Published
2021
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35. EUNADICS-AV early warning system dedicated to supporting aviation in the case of a crisis from natural airborne hazards and radionuclide clouds

Author

Brenot, Hugues, primary, Theys, Nicolas, additional, Clarisse, Lieven, additional, van Gent, Jeroen, additional, Hurtmans, Daniel R., additional, Vandenbussche, Sophie, additional, Papagiannopoulos, Nikolaos, additional, Mona, Lucia, additional, Virtanen, Timo, additional, Uppstu, Andreas, additional, Sofiev, Mikhail, additional, Bugliaro, Luca, additional, Vázquez-Navarro, Margarita, additional, Hedelt, Pascal, additional, Parks, Michelle Maree, additional, Barsotti, Sara, additional, Coltelli, Mauro, additional, Moreland, William, additional, Scollo, Simona, additional, Salerno, Giuseppe, additional, Arnold-Arias, Delia, additional, Hirtl, Marcus, additional, Peltonen, Tuomas, additional, Lahtinen, Juhani, additional, Sievers, Klaus, additional, Lipok, Florian, additional, Rüfenacht, Rolf, additional, Haefele, Alexander, additional, Hervo, Maxime, additional, Wagenaar, Saskia, additional, Som de Cerff, Wim, additional, de Laat, Jos, additional, Apituley, Arnoud, additional, Stammes, Piet, additional, Laffineur, Quentin, additional, Delcloo, Andy, additional, Lennart, Robertson, additional, Rokitansky, Carl-Herbert, additional, Vargas, Arturo, additional, Kerschbaum, Markus, additional, Resch, Christian, additional, Zopp, Raimund, additional, Plu, Matthieu, additional, Peuch, Vincent-Henri, additional, Van Roozendael, Michel, additional, and Wotawa, Gerhard, additional

Published
2021
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36. Volcanic SO2 Effective Layer Height Retrieval for OMI Using a Machine Learning Approach

Author

Fedkin, Nikita M., Li, Can, Krotkov, Nickolay A., Hedelt, Pascal, Loyola, Diego G., Dickerson, Russell R., and Spurr, Robert

Subjects
SO2 Layer height, Machine learning, Volcanoes, SO2, Atmosphärenprozessoren
Abstract

Information about the height and loading of sulfur dioxide (SO2) plumes from volcanic eruptions is crucial for aviation safety and for assessing the effect of sulfate aerosols on climate. While SO2 layer height has been successfully retrieved from backscattered Earthshine ultraviolet (UV) radiances measured by the Ozone Monitoring Instrument (OMI), previously demonstrated techniques are computationally intensive and not suitable for near real-time applications. In this study, we introduce a new OMI algorithm for fast retrievals of effective volcanic SO2 layer height. We apply the Full Physics Inverse Learning Machine (FP_ILM) algorithm to OMI radiances in the spectral range of 310–330 nm. This approach consists of a training phase that utilizes extensive radiative transfer calculations to generate a large dataset of synthetic radiance spectra for geophysical parameters representing the OMI measurement conditions. The principal components of the spectra from this dataset in addition to a few geophysical parameters are used to train a neural network to solve the inverse problem and predict the SO2 layer height. This is followed by applying the trained inverse model to real OMI measurements to retrieve the effective SO2 plume heights. The algorithm has been tested on several major eruptions during the OMI data record. The results for the 2008 Kasatochi, 2014 Kelud, 2015 Calbuco, and 2019 Raikoke eruption cases are presented here and compared with volcanic plume heights estimated with other satellite sensors. For the most part, OMI-retrieved effective SO2 heights agree well with the lidar measurements of aerosol layer height from Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) and thermal infrared retrievals of SO2 heights from the infrared atmospheric sounding interferometer (IASI). The errors in OMI retrieved SO2 heights are estimated to be 1–1.5 km for plumes with relatively large SO2 signals (> 40 DU). The algorithm is very fast and retrieves plume height in less than 10 min for an entire OMI orbit. This approach offers a promising prospect of using physics-based machine learning applications to other instruments.

Published
2021

37. Volcanic SO2 effective layer height retrieval for the Ozone Monitoring Instrument (OMI) using a machine-learning approach

Author

Fedkin, Nikita M., Li, Can, Krotkov, Nickolay A., Hedelt, Pascal, Loyola, Diego G., Dickerson, Russell R., and Spurr, Robert

Abstract

Information about the height and loading of sulfur dioxide (SO2) plumes from volcanic eruptions is crucial for aviation safety and for assessing the effect of sulfate aerosols on climate. While SO2 layer height has been successfully retrieved from backscattered Earthshine ultraviolet (UV) radiances measured by the Ozone Monitoring Instrument (OMI), previously demonstrated techniques are computationally intensive and not suitable for near-real-time applications. In this study, we introduce a new OMI algorithm for fast retrievals of effective volcanic SO2 layer height. We apply the Full-Physics Inverse Learning Machine (FP_ILM) algorithm to OMI radiances in the spectral range of 310–330 nm. This approach consists of a training phase that utilizes extensive radiative transfer calculations to generate a large dataset of synthetic radiance spectra for geophysical parameters representing the OMI measurement conditions. The principal components of the spectra from this dataset in addition to a few geophysical parameters are used to train a neural network to solve the inverse problem and predict the SO2 layer height. This is followed by applying the trained inverse model to real OMI measurements to retrieve the effective SO2 plume heights. The algorithm has been tested on several major eruptions during the OMI data record. The results for the 2008 Kasatochi, 2014 Kelud, 2015 Calbuco, and 2019 Raikoke eruption cases are presented here and compared with volcanic plume heights estimated with other satellite sensors. For the most part, OMI-retrieved effective SO2 heights agree well with the lidar measurements of aerosol layer height from Cloud–Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) and thermal infrared retrievals of SO2 heights from the infrared atmospheric sounding interferometer (IASI). The errors in OMI-retrieved SO2 heights are estimated to be 1–1.5 km for plumes with relatively large SO2 signals (>40 DU). The algorithm is very fast and retrieves plume height in less than 10 min for an entire OMI orbit.

Published
2021

38. Global Ozone Monitoring Experiment-2 (GOME-2) Daily and Monthly Level 3 Products of Atmospheric Trace Gas Columns.

Author

Ka Lok Chan, Valks, Pieter, Heue, Klaus-Peter, Lutz, Ronny, Hedelt, Pascal, Loyola, Diego, Pinardi, Gaia, Van Roozendael, Michel, Hendrick, François, Wagner, Thomas, Kumar, Vinod, Bais, Alkis, Piters, Ankie, Hitoshi Irie, Hisahiro Takashima, Yugo Kanaya, Yongjoo Choi, Kihong Park, Jihyo Chong, and Cede, Alexander

Subjects
COLUMNS, TRACE gases, OZONE, WATER vapor, NITROGEN dioxide, TROPOSPHERIC ozone, AIR pollutants
Abstract

We introduce the new GOME-2 daily and monthly level 3 product of total column ozone (O3), total and tropospheric column nitrogen dioxide (NO2), total column water vapour, total column bromine oxide (BrO), total column formaldehyde (HCHO) and total column sulphur dioxide (SO2). The GOME-2 level 3 products are aimed to provide easily translatable and userfriendly data sets to the scientific community for scientific progress as well as satisfying public interest. The purpose of this paper is to present the theoretical basis as well as the verification and validation of the GOME-2 daily and monthly level 3 products. The GOME-2 level 3 products are produced using the overlapping area weighting method. Details of the gridding algorithm are presented. The spatial resolution of the GOME-2 level 3 products is selected based on sensitivity study. The consistency of the resulting level 3 products among three GOME-2 sensors is investigated through time series of global averages, zonal averages, and bias. The accuracy of the products is validated by comparing to ground-based observations. The verification and validation results show that the GOME-2 level 3 products are consistent with the level 2 data. Small discrepancies are found among three GOME-2 sensors, which are mainly caused by the differences in instrument characteristic and level 2 processor. The comparison of GOME-2 level 3 products to ground-based observations in general shows very good agreement, indicating the products are consistent and fulfil the requirements to serve the scientific community and general public. [ABSTRACT FROM AUTHOR]

Published
2022
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40. Comparative assessment of TROPOMI and OMI formaldehyde observations and validation against MAX-DOAS network column measurements

Author

De Smedt, Isabelle, primary, Pinardi, Gaia, additional, Vigouroux, Corinne, additional, Compernolle, Steven, additional, Bais, Alkis, additional, Benavent, Nuria, additional, Boersma, Folkert, additional, Chan, Ka-Lok, additional, Donner, Sebastian, additional, Eichmann, Kai-Uwe, additional, Hedelt, Pascal, additional, Hendrick, François, additional, Irie, Hitoshi, additional, Kumar, Vinod, additional, Lambert, Jean-Christopher, additional, Langerock, Bavo, additional, Lerot, Christophe, additional, Liu, Cheng, additional, Loyola, Diego, additional, Piters, Ankie, additional, Richter, Andreas, additional, Rivera Cárdenas, Claudia, additional, Romahn, Fabian, additional, Ryan, Robert George, additional, Sinha, Vinayak, additional, Theys, Nicolas, additional, Vlietinck, Jonas, additional, Wagner, Thomas, additional, Wang, Ting, additional, Yu, Huan, additional, and Van Roozendael, Michel, additional

Published
2021
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41. First airborne in situ SO2 observations of two coal-fired power plants in Serbia and Bosnia-Herzegovina: Potential for top-down emission estimate and satellite validation

Author

Klausner, Theresa, Huntrieser, Heidi, Aufmhoff, Heinfried, Hedelt, Pascal, Loyola, Diego, Mertens, Mariano, Jöckel, Patrick, Makroum, Ismail, Kurilic, Sanja Mrazovac, Podrascanin, Zorica, Ilic, Predrag, Baumann, Robert, Gottschaldt, Klaus-Dirk, Fiehn, Alina, and Roiger, Anke-Elisabeth

Subjects
satellite validation, sulphur dioxide, air quality
Published
2021

42. EUNADICS-AV early warning system dedicated to supporting aviation in the case of a crisis from natural airborne hazards and radionuclide clouds

Author

Brenot, Hugues, Theys, Nicolas, Clarisse, Lieven, van Gent, Jeroen, Hurtmans, Daniel R., Vandenbussche, Sophie, Papagiannopoulos, Nikolaos, Mona, Lucia, Virtanen, Timo, Uppstu, Andreas, Sofiev, Mikhail, Bugliaro, Luca, Vazquez-Navarro, Margarita, Hedelt, Pascal, Parks, Michelle Maree, Barsotti, Sara, Coltelli, Mauro, Moreland, William, Scollo, Simona, Salerno, Giuseppe, Arnold-Arias, Delia, Hirtl, Marcus, Peltonen, Tuomas, Lahtinen, Juhani, Sievers, Klaus, Lipok, Florian, Rufenacht, Rolf, Haefele, Alexander, Hervo, Maxime, Wagenaar, Saskia, de Cerff, Wim Som, de Laat, Jos, Apituley, Arnoud, Stammes, Piet, Laffineur, Quentin, Delcloo, Andy, Robertson, Lennart, Rokitansky, Carl-Herbert, Vargas, Arturo, Kerschbaum, Markus, Resch, Christian, Zopp, Raimund, Plu, Matthieu, Peuch, Vincent-Henri, Van Roozendael, Michel, Wotawa, Gerhard, Brenot, Hugues, Theys, Nicolas, Clarisse, Lieven, van Gent, Jeroen, Hurtmans, Daniel R., Vandenbussche, Sophie, Papagiannopoulos, Nikolaos, Mona, Lucia, Virtanen, Timo, Uppstu, Andreas, Sofiev, Mikhail, Bugliaro, Luca, Vazquez-Navarro, Margarita, Hedelt, Pascal, Parks, Michelle Maree, Barsotti, Sara, Coltelli, Mauro, Moreland, William, Scollo, Simona, Salerno, Giuseppe, Arnold-Arias, Delia, Hirtl, Marcus, Peltonen, Tuomas, Lahtinen, Juhani, Sievers, Klaus, Lipok, Florian, Rufenacht, Rolf, Haefele, Alexander, Hervo, Maxime, Wagenaar, Saskia, de Cerff, Wim Som, de Laat, Jos, Apituley, Arnoud, Stammes, Piet, Laffineur, Quentin, Delcloo, Andy, Robertson, Lennart, Rokitansky, Carl-Herbert, Vargas, Arturo, Kerschbaum, Markus, Resch, Christian, Zopp, Raimund, Plu, Matthieu, Peuch, Vincent-Henri, Van Roozendael, Michel, and Wotawa, Gerhard

Published
2021
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43. Comparative assessment of TROPOMI and OMI formaldehyde observations and validation against MAX-DOAS network column measurements

Author

De Smedt, Isabelle, Pinardi, Gaia, Vigouroux, Corinne, Compernolle, Steven, Bais, Alkis, Benavent, Nuria, Boersma, Folkert, Chan, Ka Lok, Donner, Sebastian, Eichmann, Kai Uwe, Hedelt, Pascal, Hendrick, François, Irie, Hitoshi, Kumar, Vinod, Lambert, Jean Christopher, Langerock, Bavo, Lerot, Christophe, Liu, Cheng, Loyola, Diego, Piters, Ankie, Richter, Andreas, Rivera Cárdenas, Claudia, Romahn, Fabian, Ryan, Robert George, Sinha, Vinayak, Theys, Nicolas, Vlietinck, Jonas, Wagner, Thomas, Wang, Ting, Yu, Huan, Van Roozendael, Michel, De Smedt, Isabelle, Pinardi, Gaia, Vigouroux, Corinne, Compernolle, Steven, Bais, Alkis, Benavent, Nuria, Boersma, Folkert, Chan, Ka Lok, Donner, Sebastian, Eichmann, Kai Uwe, Hedelt, Pascal, Hendrick, François, Irie, Hitoshi, Kumar, Vinod, Lambert, Jean Christopher, Langerock, Bavo, Lerot, Christophe, Liu, Cheng, Loyola, Diego, Piters, Ankie, Richter, Andreas, Rivera Cárdenas, Claudia, Romahn, Fabian, Ryan, Robert George, Sinha, Vinayak, Theys, Nicolas, Vlietinck, Jonas, Wagner, Thomas, Wang, Ting, Yu, Huan, and Van Roozendael, Michel

Abstract

The TROPOspheric Monitoring Instrument(TROPOMI), launched in October 2017 on board the Sentinel-5 Precursor (S5P) satellite, monitors the composition of the Earth's atmosphere at an unprecedented horizontal resolution as fine as 3.5×5.5 km2. This paper assesses the performances of the TROPOMI formaldehyde(HCHO) operational product compared to its predecessor, the OMI (Ozone Monitoring Instrument) HCHO QA4ECV product, at different spatial and temporal scales. The parallel development of the two algorithms favoured the consistency of the products, which facilitates the production of long-term combined time series. The main difference between the two satellite products is related to the use of different cloud algorithms, leading to a positive bias of OMI compared to TROPOMI of up to 30% in tropical regions. We show that after switching off the explicit correction for cloud effects, the two datasets come into an excellent agreement. For medium to large HCHO vertical columns(larger than 5×1015 molec. cm-2) the median bias between OMI and TROPOMI HCHO columns is not larger than 10% (<0.4×1015 molec. cm-2). For lower columns, OMI observations present a remaining positive bias of about 20% (<0.8×1015 molec. cm-2) compared to TROPOMI in midlatitude regions. Here, we also use a global network of 18 MAX-DOAS (multi-axis differential optical absorption spectroscopy) instruments to validate both satellite sensors for a large range of HCHO columns. This work complements the study by Vigouroux et al. (2020), where a global FTIR(Fourier transform infrared) network is used to validate the TROPOMI HCHO operational product. Consistent with the FTIR validation study, we find that for elevated HCHO columns, TROPOMI data are systematically low (-25% for HCHO columns larger than 8 × 1015 molec. cm-2), while no significant bias is found for medium-range column values. We further show that OMI and TROPOMI data present equivalent biases for large HCHO levels. However, TROPOMI significantly i

Published
2021

44. A sulfur dioxide Covariance-Based Retrieval Algorithm (COBRA): application to TROPOMI reveals new emission sources

Author

Theys, Nicolas, Fioletov, Vitali, Li, Can, De Smedt, Isabelle, Lerot, Christophe, McLinden, Chris C.A., Krotkov, Nickolay, Griffin, Debora, Clarisse, Lieven, Hedelt, Pascal, Loyola, Diego, Wagner, Thomas, Kumar, Vinod, Innes, Antje, Ribas, Roberto, Hendrick, François, Vlietinck, Jonas, Brenot, Hugues, Van Roozendael, Michel, Theys, Nicolas, Fioletov, Vitali, Li, Can, De Smedt, Isabelle, Lerot, Christophe, McLinden, Chris C.A., Krotkov, Nickolay, Griffin, Debora, Clarisse, Lieven, Hedelt, Pascal, Loyola, Diego, Wagner, Thomas, Kumar, Vinod, Innes, Antje, Ribas, Roberto, Hendrick, François, Vlietinck, Jonas, Brenot, Hugues, and Van Roozendael, Michel

Abstract

Sensitive and accurate detection of sulfur dioxide (SO2) from space is important for monitoring and estimating global sulfur emissions. Inspired by detection methods applied in the thermal infrared, we present here a new scheme to retrieve SO2 columns from satellite observations of ultraviolet back-scattered radiances. The retrieval is based on a measurement error covariance matrix to fully represent the SO2-free radiance variability, so that the SO2 slant column density is the only retrieved parameter of the algorithm. We demonstrate this approach, named COBRA, on measurements from the TROPOspheric Monitoring Instrument (TROPOMI) aboard the Sentinel-5 Precursor (S-5P) satellite. We show that the method reduces significantly both the noise and biases present in the current TROPOMI operational DOAS SO2 retrievals. The performance of this technique is also benchmarked against that of the principal component algorithm (PCA) approach. We find that the quality of the data is similar and even slightly better with the proposed COBRA approach. The ability of the algorithm to retrieve SO2 accurately is further supported by comparison with ground-based observations. We illustrate the great sensitivity of the method with a high-resolution global SO2 map, considering 2.5 years of TROPOMI data. In addition to the known sources, we detect many new SO2 emission hotspots worldwide. For the largest sources, we use the COBRA data to estimate SO2 emission rates. Results are comparable to other recently published TROPOMI-based SO2 emissions estimates, but the associated uncertainties are significantly lower than with the operational data. Next, for a limited number of weak sources, we demonstrate the potential of our data for quantifying SO2 emissions with a detection limit of about 8 kt yr-1, a factor of 4 better than the emissions derived from the Ozone Monitoring Instrument (OMI). We anticipate that the systematic use of our TROPOMI COBRA SO2 column data set at a global scale will a, SCOPUS: ar.j, info:eu-repo/semantics/published

Published
2021

45. Volcanic SO2 Layer Height from UV/Vis sensors; inter-comparisons and validation

Author

ESA ATMOS 2021, Koukouli, Mariliza, Michailidis, Konstantinos, Hedelt, Pascal, Fedkin, Nikita, Clarisse, Lieven, Balis, Dimitris, Li, Can, Krotkov, Nickolay, Loyola, Diego, ESA ATMOS 2021, Koukouli, Mariliza, Michailidis, Konstantinos, Hedelt, Pascal, Fedkin, Nikita, Clarisse, Lieven, Balis, Dimitris, Li, Can, Krotkov, Nickolay, and Loyola, Diego

Abstract

info:eu-repo/semantics/published

Published
2021

46. Comparative assessment of TROPOMI and OMI formaldehyde observations and validation against MAX-DOAS network column measurements

Author

European Space Agency, Belgian Science Policy Office, Royal Belgian Institute for Space Aeronomy, German Centre for Air and Space Travel, University of Bremen, Max Planck Institute for Chemistry, Wageningen University and Research Centre, Environmental Restoration and Conservation Agency (Japan), Smedt, Isabelle de, Pinardi, Gaia, Vigouroux, Corinne, Compernolle, Steven, Bais, Alkis, Benavent, Nuria, Boersma, Folkert, Chan, K.L., Donner, Sebastian, Eichmann, K.U., Hedelt, Pascal, Hendrick, Francois, Irie, Hitoshi, Kumar, Vinod, Lambert, J. C., Langerock, Bavo, Lerot, C., Liu, Cheng, Loyola, Diego, Piters, Ankie, Richter, Andreas, Rivera Cárdenas, Claudia, Romahn, Fabian, Ryan, Robert G., Sinha, V., Theys, Nicolas, Vlietinck, Jonas, Wagner, Thomas, Wang, Teng, Yu, Huan, Van Roozendael, M., European Space Agency, Belgian Science Policy Office, Royal Belgian Institute for Space Aeronomy, German Centre for Air and Space Travel, University of Bremen, Max Planck Institute for Chemistry, Wageningen University and Research Centre, Environmental Restoration and Conservation Agency (Japan), Smedt, Isabelle de, Pinardi, Gaia, Vigouroux, Corinne, Compernolle, Steven, Bais, Alkis, Benavent, Nuria, Boersma, Folkert, Chan, K.L., Donner, Sebastian, Eichmann, K.U., Hedelt, Pascal, Hendrick, Francois, Irie, Hitoshi, Kumar, Vinod, Lambert, J. C., Langerock, Bavo, Lerot, C., Liu, Cheng, Loyola, Diego, Piters, Ankie, Richter, Andreas, Rivera Cárdenas, Claudia, Romahn, Fabian, Ryan, Robert G., Sinha, V., Theys, Nicolas, Vlietinck, Jonas, Wagner, Thomas, Wang, Teng, Yu, Huan, and Van Roozendael, M.

Abstract

The TROPOspheric Monitoring Instrument(TROPOMI), launched in October 2017 on board the Sentinel-5 Precursor (S5P) satellite, monitors the composition of the Earth's atmosphere at an unprecedented horizontal resolution as fine as 3.5×5.5 km2. This paper assesses the performances of the TROPOMI formaldehyde(HCHO) operational product compared to its predecessor, the OMI (Ozone Monitoring Instrument) HCHO QA4ECV product, at different spatial and temporal scales. The parallel development of the two algorithms favoured the consistency of the products, which facilitates the production of long-term combined time series. The main difference between the two satellite products is related to the use of different cloud algorithms, leading to a positive bias of OMI compared to TROPOMI of up to 30% in tropical regions. We show that after switching off the explicit correction for cloud effects, the two datasets come into an excellent agreement. For medium to large HCHO vertical columns(larger than 5×1015 molec. cm-2) the median bias between OMI and TROPOMI HCHO columns is not larger than 10% (<0.4×1015 molec. cm-2). For lower columns, OMI observations present a remaining positive bias of about 20% (<0.8×1015 molec. cm-2) compared to TROPOMI in midlatitude regions. Here, we also use a global network of 18 MAX-DOAS (multi-axis differential optical absorption spectroscopy) instruments to validate both satellite sensors for a large range of HCHO columns. This work complements the study by Vigouroux et al. (2020), where a global FTIR(Fourier transform infrared) network is used to validate the TROPOMI HCHO operational product. Consistent with the FTIR validation study, we find that for elevated HCHO columns, TROPOMI data are systematically low (-25% for HCHO columns larger than 8 × 1015 molec. cm-2), while no significant bias is found for medium-range column values. We further show that OMI and TROPOMI data present equivalent biases for large HCHO levels. However, TROPOMI significantly i

Published
2021

49. Supplementary material to "A Sulfur Dioxide Covariance-Based Retrieval Algorithm (COBRA): application to TROPOMI reveals new emission sources"

Author

Theys, Nicolas, primary, Fioletov, Vitali, additional, Li, Can, additional, De Smedt, Isabelle, additional, Lerot, Christophe, additional, McLinden, Chris, additional, Krotkov, Nickolay, additional, Griffin, Debora, additional, Clarisse, Lieven, additional, Hedelt, Pascal, additional, Loyola, Diego, additional, Wagner, Thomas, additional, Kumar, Vinod, additional, Innes, Antje, additional, Ribas, Roberto, additional, Hendrick, François, additional, Vlietinck, Jonas, additional, Brenot, Hugues, additional, and Van Roozendael, Michel, additional

Published
2021
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50. Comparative assessment of TROPOMI and OMI formaldehyde observations against MAX-DOAS network column measurements

Author

De Smedt, Isabelle, primary, Pinardi, Gaia, additional, Vigouroux, Corinne, additional, Compernolle, Steven, additional, Bais, Alkis, additional, Benavent, Nuria, additional, Boersma, Folkert, additional, Chan, Ka-Lok, additional, Donner, Sebastian, additional, Eichmann, Kai-Uwe, additional, Hedelt, Pascal, additional, Hendrick, François, additional, Irie, Hitoshi, additional, Kumar, Vinod, additional, Lambert, Jean-Christopher, additional, Langerock, Bavo, additional, Lerot, Christophe, additional, Liu, Cheng, additional, Loyola, Diego, additional, Piters, Ankie, additional, Richter, Andreas, additional, Rivera Cárdenas, Claudia Inés, additional, Romahn, Fabian, additional, Ryan, Robert George, additional, Sinha, Vinayak, additional, Theys, Nicolas, additional, Vlietinck, Jonas, additional, Wagner, Thomas, additional, Wang, Ting, additional, Yu, Huan, additional, and Van Roozendael, Michel, additional

Published
2021
Full Text
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