The possible effects of aerosol and moisture on cloud and precipitation over the Korea peninsula

Anthropogenic pollution in East China provides abundant aerosols into the atmosphere, inducing profound impacts on cloud properties and precipitation. In a global view, aerosols suppress precipitation because increased aerosols bring in decreased net solar radiation at the surface, which prevents the evaporation. In contrast aerosols in a cloud scale point act as cloud condensation nuclei, which may enhance precipitation if moisture is fully supplied. Finding such conditions during the summer over the Korean peninsula, we analyzed the empirical relationship between aerosol optical thickness and cloud products by relating retrieved aerosol and cloud parameters from MODIS measurements to surface rain gauge measurements from 2000 to 2007.

Cloud and precipitation formation appear to be strongly dependent upon the moisture amount supplied to the Korean peninsula. In case of sufficient moisture supply from the south and west sides of the peninsula, the elevated AOT over East China tends to be linked to thicker cloud, larger cloud droplet, elevated cloud height, enhanced cloud cover, and heavy precipitation in the Korea peninsula. In contrast, in case of moderate and weak supplies of water vapor, the elevated AOT is related to shallower cloud, smaller cloud droplet, lowered cloud height, reduced cloud cover, and week precipitation. This study may suggest a hypothesis that precipitation can be heavier if both aerosols from the northwest and very humid air from the southwest are merged into Korea and interact with each other.