ANALYSIS OF SUMMER DAILY PRECIPITATION VARIATION CHARACTERISTICS IN CHINA DURING 1961～2007

This paper analyzed summer precipitation trends and decadal variation based on daily precipitation data of 596stations from 1961to 2007throughout China.The whole country and 8sub-regions'mean series of precipitation amount,precipitation frequency,precipitation intensity of summer were calculated by using the method of area-weighted average.The precipitation was categorized into four types according to the daily rainfall amount:0.1～9.9mm/d,10.0～24.9mm/d,25.0～49.9mm/d,and above 50.0mm/d. Special attention were devoted to their contribution to the total precipitation variation in China.The results proved that the trend of China's overall summer precipitation frequency decreased,the trends of precipitation amount,precipitation intensity increased.The change of the western northwest China Region was comparatively remarkable,and three indices showed significant increase in the trends.The increase of precipitation resulted from the increased light rain frequency and moderate rain,heavy rain,torrential rain intensity.In northeast,north and eastern northwest China,the decrease of precipitation resulted from the decrease of light rain frequency.The increase of precipitation in mid-lower Yangtze basins and south China resulted from the increase of heavy rain,torrential rain frequency and torrential rain intensity.The decrease of precipitation in southwest resulted from the decrease of light rain frequency.In eight districts and China,most of the precipitation amount,precipitation frequency and precipitation intensity increased in 1990sand decreased in 2000s.In response to the decadal shift of East Asian climate in the late 1970s,the decadal shift of precipitation frequency and intensity in 8sub-regions and China all occurred in the late 1970sor early 1980s.