Spatiotemporal Characteristics of Extreme Precipitation in the Indochina Peninsula and South China

Extreme precipitation events have become more intense and frequent as a result of global warming. The Indochina Peninsula and South China (INCSC) are located in the monsoon region and thus are vulnerable to heavy rainfall and flooding. This study examined the INCSC regions’ extreme precipitation events during the wet season (May–October) from 1951 to 2015. The circulation features, interannual, interdecadal, and long-term trend characteristics of each extreme precipitation cluster were examined. The findings reveal that (1) the extreme precipitation in the INCSC region are objectively grouped into South China, Indochina Peninsula, Burma–Yunnan, and southern South China–Northern Vietnam clusters based on the position of the precipitation center. Their associated large-scale meteorological patterns (LMP) are primarily characterized by mid-high latitude wave trains and the tropical dipole circulation. The South China clusters’ LMP has a “+ − +” meridional wavetrain in the upper troposphere, which resembles the East Asia–Pacific (EAP) teleconnection pattern. However, the LMP centers are located southwestward with respect to their EAP counterparts. The key system is the negative anomaly circulation in central East China. LMP features have a “+ −” meridional wavetrain in the lower troposphere, which is located at low latitudes. The Indochina Peninsula clusters’ LMP is associated with a dipole anomaly circulation, which is broader in the lower troposphere than the upper troposphere. The LMPs of the two extreme precipitation clusters have a combination of Rossby wavetrain in the upper troposphere and the moderate tropical dipole in the lower troposphere. (2) The occurrence of extreme precipitation events in the INCSC region exhibits a significant upward trend, which is contributed by the South China and Indochina Peninsula clusters. The meridional wavetrain LMP occurrence frequency enhanced the extreme precipitation events in the South China cluster. (3) The spatial distribution of extreme precipitation of the Indochina Peninsula and South China clusters are antisymmetric with each other.