摘要
利用NCEP资料计算并分析1961—2010年西北干旱区(35°N—50°N,73°E—105°E)经纬向水汽输送、蒸发和水汽辐合辐散的变化特征,以及它们与同期西北干旱区降水之间的关系。结果显示:(1)西北干旱区冬、春、秋季经向水汽输送为净输入,纬向为净输出,总水汽输送为净输入。夏季经、纬向水汽输送均为净输出;(2)1961—2010年,西北干旱区各季节降水均增加,冬、春季降水增加显著,夏、秋季降水增加不显著。冬季纬向水汽净输出减少,导致西北干旱区冬季总水汽输送增加;春、秋季经向净输入减少和夏季经向净输出增加,导致春、夏、秋季总水汽输送减少;(3)1961—2010年,西北干旱区各季节蒸发量显著增加,且夏季增加趋势最显著;(4)各季节水汽通量散度显著减小,水汽辐合加强,且夏季水汽辐合增强最明显;(5)蒸发增大和水汽辐合增强是西北干旱区降水增加的主要原因,但外部水汽输送变化也会影响降水变化。
With global temperature increasing, climate in arid areas also has a marked change. Based on NCEP reanalysis datasets, the characteristics and changes of meridional and zonal water vapor transportation, evaporation, water vapor convergence and divergence in the arid areas （35°N - 50°N, 73°E - 105°E） of northwest China during 1961 -2010 were analyzed, at the same time, their relationships with rainfall were also discussed. Conclusions are as follows ： （ 1 ） The meridional vapor transportation was net input in winter, spring and autumn over the arid area of northwest China, whereas the zonal vapor transportation was net output, the total vapor trans- portation was also net input. In summer, both the meridional and zonal transportation were net outputs. Precipitation in the northwest arid area increased in each season during 1961 -2010, and the increasing trend was significant in winter and spring, but it was not ob- vious in summer and autumn. The decrease of zonal water vapor net output in winter resulted in an increase of total water vapor trans- port. While the decrease of zonal water vapor net input in spring and autumn as well as the increase of zonal water vapor net output in summer caused the reduction of total water vapor input in spring, summer and autumn. （3） The evaporation increased significantly in each season in the northwest arid areas, and the increasing rate was the biggest in summer. （4） The water vapor flux divergence de- creased significantly in each season, which meant the convergence of water vapor became stronger, especially in summer. （5） Consid- ering the effect of water vapor transport, evaporation and water vapor convergence, the increase of evaporation and water vapor convergence was the main positive driving force to precipitation in northwest arid area, but external vapor transportation could also affect precipitation there.
出处
《干旱气象》
2016年第3期431-439,共9页
Journal of Arid Meteorology
基金
国家自然科学基金(41471034)
中国气象局行业专项(GYHY201506001
CCSF2014)
兰州大学中央高校基本科研业务费专项资金(lzujbky-2016-194)共同资助
关键词
西北干旱区
降水
水汽输送
蒸发
水汽辐合
northwest arid area of China
precipitation
water vapor transport
evaporation
vapor convergence
