基于主动卫星遥感研究西北地区云层垂直结构特征及其对人工增雨的影响

Study on Cloud Vertical Structure Feature over Northwest China Based on Active Satellite Remote Sensing and Its Influence on Precipitation Enhancement

利用2007年1月至2008年12月CLOUDSAT和CALIPSO卫星主动遥感资料分析了我国西北3个典型区域不同云类型的宏观及微观的垂直结构特征。结果表明:黄土高原、祁连山和天山地区的年均总云分数分别为62.8%,65.2%和73.4%;3个区域的积状云在夏秋季节发展旺盛,而层状云在冬春季节占主导地位。云层垂直方向的概率密度分布具有显著的区域和季节变化特征,其峰值位于2～6 km之间。各个区域云液态水含量自云底向上有明显的递减趋势,夏季天山和祁连山地区低层具有丰富的云水资源,峰值分别达0.47 mg/m3、0.38 mg/m3。各个区域的云液态水含量峰值以冬季最小,夏季最大。对应的液态云有效粒子半径平均值位于8～16μm之间。降水云的有效粒子半径随高度上升具有明显的递减趋势,而非降水云则存在较弱的增加趋势。这种云层垂直方向上的结构变化对降水有直接影响,是评估人工增雨潜力的重要依据。

The CLOUDSAT and CALIPSO active satellite remote sensing data from January 2007 to December 2008 are used to analyze macro and micro vertical strcture characteristics of the different cloud types over three typical regions（the Loess Plateau,the Qilian Mountain region and Tishan Mountain region） in Northwest China.The results show that the total cloud fraction in the Loess Plateau,the Qilian and the Tianshan Mountain region was 62.8%,65.2% and 73.4%,respectively.Over these regions cumuliform clouds are more in summer but stratiform clouds are more in winter.And the cloud vertical probability density distribution presented obvious regional and seasonal characteristics,and the peak region appeared at 2-6 km.The cloud liquid water content showed significant seasonal variations and decreasing trend with altitude,and the maximum value is 0.47 mg/m3 in summer in Tianshan Mountain region and 0.38 mg/m3 in the Qilian Mountain region.The average effective particle radius of liquid cloud is 8-16 μm.With altitude increasing,the effective particle radius presented a significant decreasing trend for precipitation clouds,while a weak increasing trend for non-precipitation clouds.