The Characteristics Of Aerosol In China And Its Effect On Precipitation In Recent 30 Years

Aerosol optical depth(AOD) were obtained by using the visibility data and the vapor pressure over 305 stations in China from 1980 to 2007.Aiming to investigate the aerosol influence on precipitation change over China, this paper focused on the AOD characteristics and its climate effects. Moreover, AOD characteristics of the three cities of Beijing, Tianjin and Hebei region and influencing factors were analyzed. With major results as follows.It is found that:(1)The annual mean AOD has typical spatial character. There is a maximum in the Sichuan Basins for the yearly mean AOD. While the second largest are located in Yangtze River, Xinjiang area and north of China, In reverse, AOD is lower in the Yunnan-Guizhou Plateau, the northeast of China and Qinghai.Yearly-mean AOD has the annual variation,national AOD great value area scope reduces at first and then increases from spring to winter. Changes of AOD in the four seasons are an increasing trend, especially in summer and autumn.(2)The average annual rainfall decreased, but the trend is not obvious. And the spatial characteristics of annual precipitation trend was mainly present "+-+" distribution from northwest to southeast. The following level of heavy rain (<50mm) in west of northwest and the Tibetan Plateau increased significantly. Above the level of heavy rainfall (> 75mm) in northeast and north China shows a decrease in precipitation rate, especially north China. For the case of precipitation decreased significantly, above the level of heavy rainfall has the greatest contribution. (3) More than half of stations in different seasons, AOD and precipitation showed positive correlation. Aerosol optical thickness and light rain order showed a positive correlation too, that is, the AOD of 14:00 effect on light rain of 20-20 is basically boost rather than inhibition. (4) Variation of the aerosol optical depths in the three cities of Beijing, Tianjin and Hebei region have shown a downward trend nearly three decades. The relationship between AOD and precipitation were so weak. However,the falling of dust index is at least partly responsible for the decreasing of aerosol optical depth.