Abstract:
Comparison of the D2 data of ISCCP(International Satellite Cloud Climatology Project) with the cloud data of routine surface observation indicates that both the distributive patterns and climatic change trend of cloud agree well with each other.However there are some quantitative differences,especially in the north part of China,the total cloud amount of routine is less than the amount of ISCCP.On the other hand,ISCCP is comparatively complete,and then has more advantages,especially in plateau and desert where stations are sparsely distributed.We analyze the climatic characteristics of cloud over China,and point out that the distribution of total cloud amount has four centers of high value:East-China Sea area, Sichuan Basin,southeastern area of Tibetan Plateau,and Pamir Plateau.The cloud amount over mountains is more than that over plain in the northern area.The total cloud covers over all areas of North-China Plain to Qilian Mountain are decreased at a rate about 5%/10 a.The decrease over Shandong Peninsula is more severe,about 10%/10 a.This feature accords to the aggraeating dry damage.But the total cloud amounts over the middle of Kunlun and Hengduan Mountains are increased at a rate about 8%/10 a.The distribution of low-cloud amount is similar to that of the total.The low-cloud amounts over Changbai and Tianshan Mountains are more than those over the plain and basin of same latitudes.The low-cloud amount over these four places manifests its decreasing trend:East coastal area of Yangtze Delta region,Sichuan Basin,northern of Guangdong,and the turning place of Yarlung Zangbo River The decrease of Sichuan Basin is about 10%/10 a.Over Chengdu where is on the center of Sichuan Basin,the period of most manifest decrease is 1975 to 1985.In this period,the decrease of low-cloud amount is about 40%.On the other hand,the low-cloud covers over Tianshan,Pamir-Plateau,Qaidam-Basin and Hengduan Mountains are increasing.We also point out that there are cloud belts,which are relatively stable,over the mountains in the northwest part of China.These cloud belts have deep layers and contain much water,which benefit for the artificial rain-enhancement.