Orographic Flow Influence on Precipitation During an Atmospheric River Event at Davis, Antarctica

• Published in: Journal of Geophysical Research: Atmospheres
• Main Authors: Gehring, Josué, Vignon, Étienne, Billault‐roux, Anne‐claire, Ferrone, Alfonso, Protat, Alain, Alexander, Simon, Berne, Alexis
• Other Authors: Environmental Remote Sensing Laboratory Lausanne, Ecole Polytechnique Fédérale de Lausanne (EPFL), 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), Australian Bureau of Meteorology Melbourne (BoM), Australian Government, Institute for Marine and Antarctic Studies, University of Tasmania, Hobart, TAS, Australia, Australian Antarctic Division (AAD), Australian Government, Department of the Environment and Energy
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2022
• Subjects: snowfall microphysics; sublimation; orographic gravity waves; foehn; atmospheric river; Antarctica; [SDU.STU.CL]Sciences of the Universe [physics]/Earth Sciences/Climatology; Antarctic; East Antarctica; Vestfold; Vestfold Hills; Antarc*
• Online Access: https://hal.sorbonne-universite.fr/hal-03574447; https://hal.sorbonne-universite.fr/hal-03574447/document; https://hal.sorbonne-universite.fr/hal-03574447/file/JGR%20Atmospheres%20-%202022%20-%20Gehring%20-%20Orographic%20Flow%20Influence%20on%20Precipitation%20During%20an%20Atmospheric%20River%20Event%20at%20Davis%20.pdf; https://doi.org/10.1029/2021JD035210

International audience Intense snowfall sublimation was observed during a precipitation event over Davis in the Vestfold Hills, East Antarctica, from 08 to 10 January 2019. Radar observations and simulations from the Weather Research and Forecasting model revealed that orographic gravity waves (OGWs), generated by a north-easterly flow impinging on the ice ridge upstream of Davis, were responsible for snowfall sublimation through a foehn effect. Despite the strong meridional moisture advection associated with an atmospheric river (AR) during this event, almost no precipitation reached the ground at Davis. We found that the direction of the synoptic flow with respect to the orography determined the intensity of OGWs over Davis, which in turn directly influenced the snowfall microphysics. We hypothesize that turbulence induced by the OGWs likely enhanced the aggregation process, as identified thanks to dual-polarization and dual-frequency radar observations. This study suggests that despite the intense AR, the precipitation distribution was determined by local processes tied to the orography. The mechanisms found in this case study could contribute to the extremely dry climate of the Vestfold Hills, one of the main Antarctic oases.