Toward a better understanding of snowfall in Arctic using microwave remote sensing

• Main Author: Edel, Léo
• Other Authors: Laboratoire de Météorologie Dynamique (UMR 8539) (LMD), Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-École des Ponts ParisTech (ENPC)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Département des Géosciences - ENS Paris, École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), Université Paris Saclay (COmUE), Chantal Claud, Christophe Genthon
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: HAL CCSD 2019
• Subjects: Arctic; Snowfall; Space radar; Passive sounder; Microwave; Arctique; Chutes de neige; Radar spatial; Sondeur passif; Micro-ondes; [SDU.STU.CL]Sciences of the Universe [physics]/Earth Sciences/Climatology; [SDU.STU.ME]Sciences of the Universe [physics]/Earth Sciences/Meteorology; [PHYS.PHYS.PHYS-AO-PH]Physics [physics]/Physics [physics]/Atmospheric and Oceanic Physics [physics.ao-ph]; Greenland; Arctique*
• Online Access: https://tel.archives-ouvertes.fr/tel-02984776; https://tel.archives-ouvertes.fr/tel-02984776/document; https://tel.archives-ouvertes.fr/tel-02984776/file/83586_EDEL_2019_archivage.pdf

Because solid precipitation measurements at the surface are complex in Arctic, snowfall rates present significant differences between recent datasets. To further characterize arctic precipitation, microwave remote sensing is an appropriate tool. The radar observations onboard CloudSat provides rates of snowfall at the surface for a 4-years period. These retrievals are validated with in situ data, and compared to various datasets. Despite a good qualitative agreement, significant differences are observed, especially over Greenland. The regional reanalysis shows a better agreement with CloudSat retrievals than the global reanalysis, especially regarding the seasonnal distribution of snowfall rates. Then, CloudSat observations are used as a reference to evaluate the ability of passive microwave sounders to detect arctic snowfall for frequencies around 183 GHz. Detection is possible and relies mainly on brightness temperatures at 190 and 183 ± 3 GHz as well as the temperature near the surface and the integrated water vapor. A poor detection capability is observed in cold conditions and for light snowfall. Despite these limitations, the algorithm provides significant information for intense snowfalls, with good sampling due to its wide swath and long time series. Available for the last 20 years, passive microwave observations show a notable ability for a better characterization of arctic snowfall. Parce que l’incertitude des mesures des précipitations solides est importante en Arctique, les taux de chutes de neige montrent des différences marquées entre les jeux de données disponibles. Afin de caractériser plus précisément les précipitations arctiques, la télédétection spatiale micro-ondes s’avère être un outil idéal. Les observations collectées par le radar à bord du satellite CloudSat ont permis d’obtenir les taux de chutes de neige à la surface pour quatre années complètes. Ces estimations ont été validées avec des données de stations météorologiques, et comparées à diverses climatologies. Malgré un bon accord ...