Céline Vargel


PhD in Remote Sensing, Physics of Remote Sensing


Alain Royer and Ghislain Picard

Field of research

Characterization of the Arctic snowpack and climate monitoring by microwave remote sensing

The evolution of the climate system observed in recent decades implies changes in global snow cover. Regions of high northern latitudes are experiencing a more intense warming than other regions of the globe, a phenomenon called Arctic amplification. These snow cover changes are well studied in terms of snowpack distribution and persistence, but the changes in the physical properties of snow are less well known.
However, these changes can have a significant impact on ecosystems and societies. The Arctic snowpack presents specific problems. The typical structure of the Arctic mantle includes at its base a depth ice thickness of low density and on the surface of the snow denser (exceeding 450 kg m -3 in terms of density), formed by high wind speeds. Arctic environments are difficult to access because they are remote and with harsh climatic conditions. It is therefore complicated to collect both meteorological and snow cover data. Under these conditions, how can we simulate more representatively the spatial and temporal evolutions of polar snowpacks? It is to this problem that this doctoral thesis will attempt to respond through different objectives, the main one being to analyze the evolution of snow cover, in particular surface density, in the Arctic region in relation to climate variability. First by working on the modeling of the snowpack, improving the estimation of physical properties through the implementation of a snowpack evolution modeling chain using ERA-Interim meteorological reanalysis data and the SURFEX-Crocus snowpack evolution model. Models of snowpack evolution struggle to reproduce the typical structure of the Arctic mantle because the physical processes involved are not the same as those present in the subarctic or alpine domains where these models were originally developed. Modifications were made to the SURFEX-Crocus model to simulate the structure of the Arctic snowpack in a more realistic manner. The data collected by the GRIMP team at the Université de Sherbrooke will make it possible to validate the simulations carried out in this way. The coupling of snowpack simulations with the SMRT radiative transfer model will also allow spatial and temporal validation using microwave satellite observations. One objective of this study is to then carry out a climate analysis targeting the study of temporal and spatial changes in the Arctic mantle in relation to climate change.