ANALYSIS OF GLOBAL TOTAL CLOUD AMOUNT VARIATION OVER THE PAST 20 YEARS

Cloud plays a crucial role through modulating the radiation budget and water cycles in the earth' s climate system, thus influences the climate significantly.Global warming accelerates over the past 20 years, analyzing global cloud amount variation during this period can not only promote the understanding to the interaction between the cloud and climate but also help to guide the development of the climate model.By investigating the International Satellite Cloud Climatology Project (ISCCP)D2 dataset, results show that the cloud amount distribution is mainly affected by the atmospheric circulation, and the global mean total cloud amount is about 67%;increasing trend of global annual mean cloud amount reverses in 1987 and there is a decrease trend for global mean total cloud amount with the deduction of about 4% from 1987 to 2000 ;also, the cloud amount distribution takes on remarkable regional features, which tends to decrease in most tropical and mid-latitude areas while increase slightly in high-latitude, especially over the Antiarctic.