Implications during transitional periods of improvements to the snow processes in the land surface scheme ‐ hydrological model WATCLASS

The representation of snow processes is crucial in both hydrological models and land surface schemes. The importance of the detailed physical representation of four snow processes in the WATCLASS hydrological‐ land surface scheme model is examined. The snow processes are: the occurrence of mixed precipitation; the density of fresh snow; the maximum snowpack density; and canopy snowfall interception. It is shown that the inclusion of the non‐static processes does not significantly improve the simulated streamflow. The changes in the simulation of state variables, in particular, the snowpack depth, snow water equivalent, soil temperature and soil moisture content are small, but may become important during transitional periods, such as the initial accumulation and depletion of snow‐covered areas during snowmelt. This substantially alters the surface heat fluxes during these periods.