Precipitation over the Middle Tianshan Mountains and Their Northern Slopes: Variations and Their Cause
The changes of water resources and the reasons which cause the changes over the middle Tianshan Mountains between 42. 5 N and 45. 0 N,and 85. 0°E and 90. 0°E were analyzed by using observed data of 17 meteorological stations during the past 40 years and monthly mean data provided by NCEP/NCAR from 1950 to 2000. In this area the annual mean precipitation was gradually going up and increasing obviously in summer and winter. At the same time,the increase in annual mean precipitation of mountain areas was more than that of the surrounding plains. Mean decadal precipitation of 17 stations came down form the 1960s to the 1970s,but went up from the 1980s to the 1990s. Moreover,the precipitable water showed an increasing trend. In the atmosphere over the area of 2. 5 × 5. 0,the annual influent water vapor amount was 9 217. 8 × 108 m3,the annual effluent water vapor amount was 8 625.7 × 108 m3,and annual net water vapor amount was 592. 0×108 m3,averaged over the past 50 years. The influent water vapor amount in summer mainly contributes to annual net water vapor amount. Only 6. 4% of annual influent water vapor amount contributed to precipitation,which was lower than that of the China mainland. The water budget was inclined to reduce from the 1950s to the 1990s but slightly increased in the 1990s. Considering runoff goes up and glaciers retreat,it is thought that one reason to cause the rainfall increasing over the middle Tianshan Mountains is the increase of the locally circulatory water amount and the locally circulatory frequency.
Middle Tianshan Mountain and their northern slopesprecipitationprecipitable waterwater vapor budgetrunoffglacier
NETL
NSTL
万方数据
维普
