Study of Antarctic precipitation by radar remote sensing, in situ observations, and intercomparison of climate models.

• Main Author: Palerme, Cyril
• Other Authors: Laboratoire de glaciologie et géophysique de l'environnement (LGGE), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB Université de Savoie Université de Chambéry )-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB Université de Savoie Université de Chambéry )-Centre National de la Recherche Scientifique (CNRS), Ce projet a été financé par une allocation doctorale de recherche de la Région Rhône-Alpes., Université de Grenoble, Christophe Genthon, Chantal Claud
• Format: Doctoral or Postdoctoral Thesis
• Language: French
• Published: HAL CCSD 2014
• Subjects: Antarctica; remote sensing; in-situ observations; sea-level; Antarctique; precipitation; télédétection; observations in-situ; niveau des mers; [SDE]Environmental Sciences; [SDU.OCEAN]Sciences of the Universe [physics]/Ocean; Atmosphere; Antarctic; Dumont d’Urville; Antarc*; Antarctique*; Ice Sheet
• Online Access: https://hal.archives-ouvertes.fr/tel-01231817; https://hal.archives-ouvertes.fr/tel-01231817/document; https://hal.archives-ouvertes.fr/tel-01231817/file/These.pdf

During the 21st century, precipitation is expected to increase in polar regions. InAntarctica, this would lead to an increase in snow accumulation over the continent,which would represent a positive contribution to the ice sheet mass balance, and thus anegative contribution to sea level. Almost all the climate models predict a precipitationincrease in Antarctica during the 21st century, but this change differs widely according tothe models. Moreover, the current precipitation rate simulated by these models divergegreatly. However, because no reliable observation of Antarctic precipitation was availableso far, it was not possible to benchmark climate models.In this study, data from the cloud profiling radar onboard the CloudSat satellite havebeen used to produce the first climatology of Antarctic precipitation from observations.This climatology agrees well with ERA Interim reanalysis, the production of which isconstrained by various in situ and satellite observations, but does not use any data fromCloudSat. The mean snowfall rate from CloudSat observations is 171 mm/an over theAntarctic ice sheet, north of 82°S. The maximum snowfall rate is observed during thefall, while the minimum snowfall rate occurs in spring.Because in-situ measurements are necessary to evaluate remote sensing observations,a field experiment has been developed at Dumont d’Urville station in Antarctica formeasuring precipitation. Optical sensors have been set up at different levels on a 73-meter tower in order to separate snowfall from blowing snow events. Snow flux measuredat different heights should be similar during snowfall without blowing snow, whereas agradient shoud be observed if blowing snow occurs. The system has been evaluated andcompared to the ECMWF operational analysis.Finally, simulations from the climate models used for the last IPCC report have beencompared to the new satellite climatology. All the models produce a higher snowfall ratethan the snowfall observed with CloudSat. Precipitation increase predicted in ...