A SIMPLIFIED MODEL STUDY ON THE SHORT-TERM CLIMATIC EFFECT OF SNOWFALL ANOMALY IN MID-HIGH LATITUDES

Abstract:

A simulation of the annual variation of temperature and moisture in the atmosphere and sublayer of soil in mid-high latitudes has been performed with a one-dimensional atmosphere-land coupled model, in which snowmelt process is included. The computed temperature variations in each latitudinal belt are con-sistent with the seasonal change of snowextent over continents in the Northern Hemisphere.To analyse the short-term climatic effect of snowfall anomaly, two sets of experiments have carried out by using the above simplified model, i. e. 1) the snowmelt period is earlier than the climatic mean and 2) snowdepth is less than the climatic mean. The results are shown in the present paper. In the first ex-periment, snow melts earlier, and comparing with the normal annual variation, the absorption of solar radia-tion increases significantly due to the earlier decrease of albedo. Thus the surface temperature is higher, and latent and sensible heat fluxes are enhanced. This process is characterized by thermal anomaly. In less snow-depth experiment, the soil is drier after snowmelting, and thus evaporation and precipitation are reduced. The hydrological anomaly constitutes its main character which will continue till August. In summary, the snowfall anomaly is an important factor in the formation of dry-warm or cold-wet climate in spring and summer.