This Study is led by Philippe Peylin and Catherine Ottle from IPSL.

The main CCI ECVs used in this Study are Snow Cover, Land Cover, Land Surface Temperature, Fire, and Biomass.

It is estimated that this Study will run from September 2023 until February 2025.

The Study's main objective is to improve our understanding and modeling of snow-vegetation-atmosphere feedback, with the IPSL climate model (LMDZORCHIDEE) and various CCI products (especially snow products). The Study comprises several parts. The first part involves data analysis including consistency check/analysis between Snow Cover (mass & extent), Land Cover and other CCI products (LST; Fire; Biomass; LAI) + Albedo with analysis of the differences between short and tall vegetation and Deciduous & Evergreen. The second part involves ORCHIDEE model evaluation with the evaluation of the simulated snow cover dynamics (mass and extent) and snow albedo using simulations with prescribed climate forcing (e.g., ERA5) and define a set of key “homogeneous points” for the identification of model biases. The third part involves model improvement with improved soil thermics (carbon impact on soil thermal properties; ongoing work) and SCF parameterizations and accounts for Shrubs and the representation of Snow - Vegetation dynamics. The fourth part involves Snow model parameter optimisation with model sensitivity experiments to identify critical parameters (Morris / Sobol approaches) and multi-site optimisation (local/global approaches, History Matching etc.) using Albedo, SCF and SWE data. The fifth, optional, part is to explore Coupled Model simulations with the use of the Coupled LMDZ -ORCHIDEE model (AMIP type simulation: fixed SST, SIC) and exploring historical simulations to analyse the impact of the “improved snow model” on surface-atmosphere feedbacks.

Results and conclusions

Results and conclusions will be provided once the Study is complete.