Changes in Persistent and Non-Persistent Flood Season Precipitation over South China During 1961-2010

The characteristics and possible causes of changes in persistent precipitation (PP) and non-persistent precipitation (NPP) over South China during flood season are investigated using daily precipitation data from 63 stations in South China and NCEP/NCAR reanalysis data from 1961 to 2010. This investigation is performed using the Kendall's tau linear trend analysis, correlation analysis, abrupt climate change anal-ysis, wavelet analysis, and composite analysis techniques. The results indicate that PP dominates total precipitation over South China throughout the year. The amounts of PP and NPP during flood season vary primarily on a 2-5-yr oscillation. This oscillation is more prominent during the early flood season (EFS; April-June). NPP has increased significantly over the past 50 years while PP has increased slightly during the whole flood season. These trends are mainly due to a significant increase in NPP during the EFS and a weak increase in PP during the late flood season (LFS; July-September). The contribution of EFS NPP to total flood season precipitation has increased significantly while the contribution of EFS PP has declined. The relative contributions of both types of precipitation during LFS have not changed significantly. The increase in EFS NPP over South China is likely related to the combined effects of a stronger supply of cold air from the north and a weaker supply of warm, moist air from the south. The increase in NPP amount may also be partially attributable to a reduction in the stability of the atmosphere over South China.