The model SURFEX/ISBA-Crocus is developed by the CNRM/CEN (https://www.umr-cnrm.fr/spip.php?article265).

It is a one-dimensional multi-layer physical snow model, based on thermodynamics, simulating the energy balance of the snowpack (Brun et al., 1989; Vionnet et al., 2012). Its main objective is to represent the detailed evolution of the internal properties of the snowpack (thermal transfer, radiative transfer). The snowpack is represented as a set of up to 50 snow layers. Each layer is characterized by its density, age, enthalpy, mass, sphericity and specific surface area.

Crocus reproduces the time-evolution of these variables by accounting for new snow deposition, metamorphism, settlement, heat exchanges, melting and refreezing for each layer, at a time step of 15min. This description makes possible to realistically represent the flows of energy at the interfaces of the snowpack (ground and atmosphere).

Fig. From Vionnet et al., 2012. Main physical processes and model variables of Crocus Model.

In the iFROG project, this model will be used to simulate the SMB of the three studied glaciers in order to provide refined future glaciological projections including feedback of precipitation and impacts of future rain/snow transition height.

This model has been chosen due to its ability to accurately represent snow albedo processes (Dumont et al., 2012) and its performance in previous SMB simulations (Réveillet et al., 2018).

In addition, in agreement with the iFROG objectives, Crocus is able to take into account and calculate the liquid water content, the liquid water percolation, snow metamorphism and settlement, and the albedo/light penetration depth which are clue variables for detecting the impact of the snow/rain transition on future SMB.

Updated on 16 May 2022