A coupled soil-snow-atmosphere transfer model

A comprehensive search of the literature reveals that most snow models motivated by snow hazard investigation do not take into account the liquid water and vapor transport in the soil. A soil-snow-atmosphere transfer model has been developed by coupling a slightly modified version of the SNTHERM snow physics model with our land surface process (LSP) model. The coupled one-dimensional model includes two-way liquid and vapor moisture transport between snow and soil, which are ignored in SNTHERM, and includes ice lenses and ponding in soil, which are absent in both LSP and SNTHERM models. The coupled model, initialized with snow properties from measurements of the NASA Cold Land Processes Field Experiment (CLPX), was run for 14 days to examine the effects of snow melting and refreezing on soil temperature and moisture distributions for a bare soil in Colorado during early spring. Preliminary results show the simulation in temperature show more agreement with considering the mass and energy transport to the soil. The simulation is less efficient in liquid moisture content because this site may be heterogeneous, with a large extent of buried vegetation or the occurrence of the ice lens and ponding. There is a 35% maximum difference downward in soil heat flux at the snow/soil interface between SSAT and SNTHERM. This coupled model will be used to develop a further soil-snow-vegetation-atmosphere transfer model calibrated for prairie and alpine terrains. It will also help prepare the cold lands community to interpret the satellite brightness observations from satellite missions, such as the Soil Moisture and Ocean Salinity (SMOS) mission and the Hydrosphere State (HYDROS) mission.