Validation of the TROPOspheric Monitoring Instrument (TROPOMI) surface UV radiation product

• Main Authors: Lakkala, Kaisa, Kujanpaa, Jukka, Brogniez, Colette, Henriot, Nicolas, Arola, Antti, Aun, Margit, Auriol, Frederique, Bais, Alkiviadis, Bernhard, Germar, De Bock, Veerle, Catalfamo, Maxime, Deroo, Christine, Diemoz, Henri, Egli, Luca, Forestier, Jean-Baptiste, Fountoulakis, Ilias, Garane, Katerina, Garcia, Rosa Delia, Grobner, Julian, Hassinen, Seppo, Heikkila, Anu, Henderson, Stuart, Hulsen, Gregor, Johnsen, Bjørn, Kalakoski, Niilo, Karanikolas, Angelos, Karppinen, Tomi, Lamy, Kevin, Leon-Luis, Sergio F., Lindfors, Anders V., Metzger, Jean-Marc, Minvielle, Fanny, Muskatel, Harel B., Portafaix, Thierry, Redondas, Alberto, Sanchez, Ricardo, Siani, Anna Maria, Svendby, Tove, Tamminen, Johanna
• Other Authors: Université de Lille, CNRS, Laboratoire d'Optique Atmosphérique (LOA) - UMR 8518, Finnish Meteorological Institute FMI, Space and Earth Observation Centre Sodankylä, University of Tartu, Department of Physics Thessaloniki, Institut Royal Météorologique de Belgique Bruxelles - Royal Meteorological Institute of Belgium IRM, Aosta Valley Regional Environmental Protection Agency ARPA, CNR Institute of Atmospheric Sciences and Climate ISAC, Physikalisch-Meteorologisches Observatorium Davos/World Radiation Center PMOD/WRC, Laboratoire de l'Atmosphère et des Cyclones LACy, Laboratory of Atmospheric Physics Thessaloniki, Agencia Estatal de Meteorología AEMet, Universidad de Valladolid Valladolid UVa, Norwegian Radiation and Nuclear Safety Authority, Aristotle University of Thessaloniki, Izaña Atmospheric Research Center IARC, Observatoire des Sciences de l'Univers de La Réunion OSU-Réunion, Servicio Meteorológico Nacional Buenos Aires, Dipartimento di Fisica Roma La Sapienza, Norwegian Institute for Air Research NILU
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2024
• Subjects: Arctic; Antarctic; The Sentinel; albedo; Antarc*; Subarctic
• Online Access: https://hdl.handle.net/20.500.12210/102402

The TROPOspheric Monitoring Instrument (TROPOMI) onboard the Sentinel-5 Precursor (S5P) satellite was launched on 13 October 2017 to provide the atmospheric composition for atmosphere and climate research. The S5P is a Sun-synchronous polar-orbiting satellite providing global daily coverage. The TROPOMI swath is 2600 km wide, and the ground resolution for most data products is 7.2×3.5 km2 (5.6×3.5 km2 since 6 August 2019) at nadir. The Finnish Meteorological Institute (FMI) is responsible for the development of the TROPOMI UV algorithm and the processing of the TROPOMI surface ultraviolet (UV) radiation product which includes 36 UV parameters in total. Ground-based data from 25 sites located in arctic, subarctic, temperate, equatorial and Antarctic areas were used for validation of the TROPOMI overpass irradiance at 305, 310, 324 and 380 nm, overpass erythemally weighted dose rate/UV index, and erythemally weighted daily dose for the period from 1 January 2018 to 31 August 2019. The validation results showed that for most sites 60 %–80 % of TROPOMI data was within ±20 % of ground-based data for snow-free surface conditions. The median relative differences to ground-based measurements of TROPOMI snow-free surface daily doses were within ±10 % and ±5 % at two-thirds and at half of the sites, respectively. At several sites more than 90 % of cloud-free TROPOMI data was within ±20 % of ground-based measurements. Generally median relative differences between TROPOMI data and ground-based measurements were a little biased towards negative values (i.e. satellite data < ground-based measurement), but at high latitudes where non-homogeneous topography and albedo or snow conditions occurred, the negative bias was exceptionally high: from −30 % to −65 %. Positive biases of 10 %–15 % were also found for mountainous sites due to challenging topography. The TROPOMI surface UV radiation product includes quality flags to detect increased uncertainties in the data due to heterogeneous surface albedo and rough terrain, which ...