SNOW DISTRIBUTION AND MELT IN CENTRAL TIEN-SHAN, SUSAMIR VALLEY

Using data collected an expeditions and long-term records, evaluations of snow accumulation and melt in high-altitude catchments, typical of much of the central Tien Shan, are presented. Over areas of about 500 km(2), the main factor influencing spatial distribution of precipitat ion and snow is elevation. Maximum snow water equivalent, dates of max imum accumulation, and the duration of snow cover plot as a parabolic function of altitude. Over areas larger than 500 km(2), the effects of rain shadow are strengthened in the cold season and precipitation dec reases in eastern direction. However, during the warm season, the main predictor of precipitation and snow distribution is elevation. In are as less than 500 km(2), exposure has a significant influence on snow r edistribution. However, there is a similarity in snow distribution in spite of differences in elevations or the angle of inclination of slop es. Highest correlation length in snow accumulation occurred at a 50 t o 60 km horizontal distance and up to 1.0 km in altitude. Solar radiat ion contributed 74% of energy for snowmelt and evaporation, and turbul ent heat contributed 26% during expeditionary observations in May 1992 . Average daily snow evaporation used 10% of available energy while sn owmelt used 90%.