Spatial patterns of short‐term extreme precipitation and their causes

Abstract The spatial distribution of extreme precipitation significantly affects flow‐producing processes and flooding. Previous studies on heavy rainfall have mainly emphasized the temporal distribution characteristics, with little emphasis on rainfall spatial patterns. We objectively classified 3‐h scale extreme precipitation spatial patterns (EPSPs) in Guangdong Province, China. We calculated the importance of the influencing factors on EPSPs, analysed weather backgrounds corresponding to various EPSPs, and explained the causes of extreme precipitation. We found that the incidence of most EPSPs increased significantly over this 40‐year period, and this increase has been particularly pronounced since the beginning of the 21st century. The Pacific Decadal Oscillation (PDO) was found to be the main factor influencing the extreme precipitation events (EPEs) in western Guangdong, and the weakening of the PDO contributed to the occurrence of EPEs in these areas. Urbanization was the main factor contributing to the increase in EPEs in the southern and coastal areas of Guangdong. The EPSPs in central Guangdong were caused by a southwest jet stream and topographic uplift. Extreme precipitation in southern and coastal Guangdong was mainly triggered by the convergent shear of southwesterly winds. The EPSPs over western Guangdong were caused by the low vortex in western Guangdong and the influx of large amounts of water vapour from the southern ocean. This study has provided new ideas for the study of the formation process and mechanism of localized heavy precipitation as well as an important reference for the simulation of runoff in coastal areas.