Search

Your search keyword '"Romahn, Fabian"' showing total 21 results
Start Over Author "Romahn, Fabian" Publication Year Range Last 3 years
21 results on '"Romahn, Fabian"'

2. 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
Full Text
View/download PDF

3. 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
Full Text
View/download PDF

4. Comparison of Cloud Parameters from GOME-2 and Assessment of Cloud Impact on Tropospheric NO2 and HCHO Retrievals

Author

Argyrouli, Athina, primary, Lutz, Ronny, additional, Romahn, Fabian, additional, Molina García, Víctor, additional, Loyola, Diego, additional, Seo, Sora, additional, Valks, Pieter, additional, De Smedt, Isabelle, additional, Boersma, Folkert, additional, Tilstra, Lieuwe Gijsbert, additional, Stammes, Piet, additional, and Compernolle, Steven, additional

Published
2023
Full Text
View/download PDF

6. Assessing the quality of the Sentinel-5p TROPOMI cloud products and their reprocessing using ground-based Cloudnet data

Author

Compernolle, Steven, primary, Argyrouli, Athina, additional, Lutz, Ronny, additional, Sneep, Maarten, additional, Lambert, Jean-Christopher, additional, Fjaeraa, Ann Mari, additional, Granville, José, additional, Hubert, Daan, additional, Keppens, Arno, additional, Loyola, Diego, additional, O'Connor, Ewan, additional, Pinardi, Gaia, additional, Rasson, Olivier, additional, Romahn, Fabian, additional, Stammes, Piet, additional, Verhoelst, Tijl, additional, and Wang, Ping, additional

Published
2023
Full Text
View/download PDF

9. Air quality impacts of COVID-19 lockdown measures detected from space using high spatial resolution observations of multiple trace gases from Sentinel-5P/TROPOMI

Author

Levelt, Pieternel F., primary, Stein Zweers, Deborah C., additional, Aben, Ilse, additional, Bauwens, Maite, additional, Borsdorff, Tobias, additional, De Smedt, Isabelle, additional, Eskes, Henk J., additional, Lerot, Christophe, additional, Loyola, Diego G., additional, Romahn, Fabian, additional, Stavrakou, Trissevgeni, additional, Theys, Nicolas, additional, Van Roozendael, Michel, additional, Veefkind, J. Pepijn, additional, and Verhoelst, Tijl, additional

Published
2022
Full Text
View/download PDF

10. Comparison of Cloud Parameters from GOME-2 and Assessment of Cloud Impact on Tropospheric NO2 and HCHO Retrievals.

Author

Argyrouli, Athina, Lutz, Ronny, Romahn, Fabian, García, Víctor Molina, Loyola, Diego, Seo, Sora, Valks, Pieter, De Smedt, Isabelle, Boersma, Folkert, Tilstra, Lieuwe Gijsbert, Stammes, Piet, and Compernolle, Steven

Subjects
CLOUDS, OXYGEN, TRACE gases, AIR quality, CLIMATE change
Abstract

In recent decades, there has been an increasing interest in making use of satellite measurements for identifying trends in atmospheric composition and climate. Instruments like GOME-2 and TROPOMI are dedicated to air-quality and global trace gas monitoring. For the accurate retrieval of columnar information of the trace gases, cloud correction is necessary. This work is meant to examine the quality of the GOME-2 operational cloud product from AC SAF and to propose enhancements of the current dataset to improve the retrieval of the NO2 and HCHO tropospheric gases. [ABSTRACT FROM AUTHOR]

Published
2023
Full Text
View/download PDF

15. Formaldehyde column retrievals from the GEMS mission and evaluation against TROPOMI data

Author

De Smedt, Isabelle, primary, Van Gent, Jeroen, additional, Vlietinck, Jonas, additional, Yu, Huan, additional, Lerot, Christophe, additional, Theys, Nicolas, additional, Pinardi, Gaia, additional, Hendrick, François, additional, Romahn, Fabian, additional, Park, Rokjin, additional, Lee, Gitael, additional, Kwon, Hyeong Ahn, additional, Loyola, Diego, additional, and Van Roozendael, Michel, additional

Published
2022
Full Text
View/download PDF

21. TROPOMI tropospheric ozone column data: geophysical assessment and comparison to ozonesondes, GOME-2B and OMI

Author

Hubert, Daan, primary, Heue, Klaus-Peter, additional, Lambert, Jean-Christopher, additional, Verhoelst, Tijl, additional, Allaart, Marc, additional, Compernolle, Steven, additional, Cullis, Patrick D., additional, Dehn, Angelika, additional, Félix, Christian, additional, Johnson, Bryan J., additional, Keppens, Arno, additional, Kollonige, Debra E., additional, Lerot, Christophe, additional, Loyola, Diego, additional, Maata, Matakite, additional, Mitro, Sukarni, additional, Mohamad, Maznorizan, additional, Piters, Ankie, additional, Romahn, Fabian, additional, Selkirk, Henry B., additional, da Silva, Francisco R., additional, Stauffer, Ryan M., additional, Thompson, Anne M., additional, Veefkind, J. Pepijn, additional, Vömel, Holger, additional, Witte, Jacquelyn C., additional, and Zehner, Claus, additional

Published
2021
Full Text
View/download PDF

Catalog

Books, media, physical & digital resources
See catalog results