祁连山云和空中水汽资源的季节分布与演变

祁连山云和空中水汽资源具有明显的季节变化特征：总云量春季最多，夏季次之，低云量夏季最多，春季次之。近45年中的春季和夏季，总云量在减少，低云量在增加，对应降水也在增加；秋季三者都为减少趋势；冬季总云量和降水在增加，但低云却呈减少趋势。相关分析表明，总云和降水在夏季、秋季呈显著正相关，低云和降水在春季、夏季及秋季呈正相关；值得注意的是冬季低云和降水在祁连山的中东段呈负相关，但通不过信度检验。空中水汽主要沿两条路径输送到祁连山，平均状况下祁连山存在较强的水汽辐合，且东段辐合（-0.1～-0.05 kg/(m2·s）)强于中西段（-0.05～0 kg/(m2·s））。地中海、黑海、里海、咸海、阿拉伯海和孟加拉湾是祁连山的水汽输送源地，但各个季节又有所不同。祁连山区域的水汽收支表明，春季净水汽通量在1979年以后一直为正且呈增加趋势，夏季整个区域基本上是个“水汽汇”，秋季和冬季则一直为负。分析认为祁连山春、夏两季空中云水资源具有较好的开发潜力。

The Seasonal Distribution and Time-Varying of the Cloud and Vapor Flux in Qilian Mountain Areas

Based on the seasonal distribution character and its change about cloud and water vapor in Qilian mountain, the results as following: The total cloud is most in spring and it is take second place in summer. The low cloud is most in summer, it is take second place in spring. Both total cloud and low cloud is least in autumn and in winter. During the past 45 years, total cloud is decreasing and low cloud is increasing in spring and in summer, the precipitation is increasing at the same time, total cloud and low cloud and precipitation have a decreased tendency in autumn, total cloud and precipitation is adding in winter, but low cloud is reducing in winter. There are positive correlation between total cloud and precipitation in summer and in autumn. The positive correlation happened between low cloud and precipitation in spring and in summer and in autumn, but has negative correlation in winter at the middle and eastern part of Qilian mountain, which is not notable in winter. Vapor flux is transported to the Qilian mountain areas along two path, there is strong vapor flux convergence in this region, the value is from 0.1 to 0.05 kg/(m2·s) in the eastern part of Qilian mountain and is from 0.05 to 0 kg/(m2·s） in the middle and western part. Med and the Caspian sea and the Black sea and the Aral sea are the headstream of water vapor of Qilian mountain, but it is different in every season. The net vapor flux value is positive in spring after 1979 and which is adding also, which is positive and has a increasing trend in summer in past 45 years, but is negative in autumn and in winter. In brief, the water vapor resource in Qilian mountain has a good potency for exploitation in spring and summer.