乌鲁木齐河流域山区冬季积雪蒸发观测的主要结果

Results of Snow Surface Sublimation Measurements in the Mountain Area of Urumqi River Basin

According to the evaporation pan measurements, the daytime snow surface sublimation rate and night-time condensition rate are 0.012 mm/h and 0.005-0.010 mm/h, respectively, in the mid-alpine area of the river basin during midlle winter mounths. The daily sublimation from the snow pack reachs to 0.03 mm in January and 0.16 mm in February in the mid-alpine area. Since the climate in the high alpine area is drier in the winter, the average daily sublimation increases to 0.21 mm in February and 0.54 mm in March, which is close to the daily sublimation from snow surface of the Glacier No. 1 in the summer of July and August. Snow surface sublimation in the high alpine area mainly depends on the thermal condition, that is , it changes proportionally along with the daily maximum air temperature. The monthly sublimation ranges from 4.6-5.5 mm in February and 7.9-9.5 mm in March, respectively, in the river source area, accounting for 55-100 percent of the monthly precipitation.