Are precipitation anomalies associated with aerosol variations over eastern China?

Abstract

In eastern China (EC), the strong anthropogenic emissions deteriorate the atmospheric environment, building a south–north zonal distribution of high aerosols harbored by the upstream Tibetan and Loess plateaus in China. This study climatologically analyzed the interannual variability in precipitation with different intensities in association with aerosol variations over the EC region from 1961 to 2010 by using precipitation and visibility data from more than 50 years and aircraft and surface aerosol data from recent years in China, and the impacts of aerosol variations on interannual variability in the intensity of precipitation events and their physical causes are investigated. We found that the frequency of light rain has significantly decreased and the occurrence of rainstorms, especially severe rainstorms, has significantly increased over recent decades. The extreme precipitation events presented an interannual variability pattern similar to that of the frequent haze events over EC. Accompanied by the frequent haze events in EC, light rain frequency significantly decreased and extremely heavy precipitation events have occurred more frequently. During the 1980s, the regional precipitation trends in EC showed an obvious transform from more light rain to more extreme rainstorms. The running correlation analysis of interdecadal variation further verified that the correlation between the increasing aerosols and frequencies of abnormal precipitation events tended to be more significant in EC. The correlation between atmospheric visibility and low cloud amounts, which are both closely related to aerosol concentrations, was positive in the north and negative in the south, and the spatial distribution of the variability in regional rainstorm frequency was positive in the south and negative in the north. After the 1990s, the visibility in summer season deteriorated more remarkably, light rain frequency decreased noticeably, and rainstorms and extraordinarily heavy rainfall occurred more frequently. There were significant differences in the interdecadal variation trends in light rain and rainstorm events between the highly aerosol-polluted area in EC and the relatively clean area on the western plateaus of China. The aircraft measurements over EC confirmed that the diameters of cloud droplets decreased under high aerosol concentration conditions, thereby inhibiting weak precipitation process.