MODELING THE SNOW COVER IN CLIMATE STUDIES - 2 - THE SENSITIVITY TO INTERNAL SNOW PARAMETERS AND INTERFACE PROCESSES

In order to find an optimal complexity for snow-cover models in climat e studies, the influence of single snow processes on both the snow mas s balance and the energy fluxes between snow surface and atmosphere ha s been investigated. Using a sophisticated model, experiments were per formed under several different atmospheric and regional conditions (Ar ctic, midlatitudes, alpine regions). A high simulation quality can be achieved with a multi layered snow-cover model resolving the internal snow processes (cf. part 1,[Loth and Graf, this issue]). Otherwise, la rge errors can occur, mostly in zones which are of paramount importanc e for the entire climate dynamics. Owing to simplifications of such a model, the mean energy balance of the snow cover, the turbulent heat f luxes, and the long-wave radiation at the snow surface may alter by be tween 1 W/m(2) and 8 W/m(2). The snow-surface temperatures can be syst ematically changed by about 10 K.