A Model Study of the Short-Term Climatic and Hydrologic Effects of Sudden Snow-Cover Removal

Abstract

This paper describes the results from a set of numerical experiments which stimulate the effect of a large-scale removal of snow cover in middle and high latitudes during the early spring season. This is done through use of a simplified general circulation model with a limited computational domain and idealized geography. It is found that removal of snow cover reduces the water available to the soil through snowmelt and decreases soil moisture in this region during the following seasons. Furthermore, it also reduces surface albedo in this region and increases absorption of insolation by the ground surface. This, in turn, heats the ground surface and allows more evaporation to occur. However, the change of evaporation is relatively small owing to the low values of surface temperature in high latitudes. Therefore, the negative anomaly of soil moisture induced initially by the removal of snow cover persists for the entire spring and summer seasons. The removal of snow cover also affects the thermal and dynamical structure of the atmosphere. It is found that the increase of surface temperature extends into the upper troposphere thereby reducing both meridional temperature gradient and zonal wind in high latitudes.