Source of Evaporation for the Seasonal Precipitation in the Pearl River Delta, China

The changes in the occurrence and intensity of precipitation have been widely observed around the world. However, exploring the causes of changes in precipitation remains challenging. To better explore the causes of precipitation changes, the evaporation sources of such precipitation were identified. The region from which evaporative sources contribute to precipitation in a sink region is called the precipitationshed. Based on the ERA5 reanalysis data, we identified the seasonal precipitationshed in the Pearl River Delta (PRD), one of the most densely urbanized regions in the world, using the Water Accounting Model-2layer. The precipitationshed in the PRD has larger variation in summer and autumn, and differences in the responses of different types of precipitation to the change in the precipitationshed were identified. In autumn, results show that light precipitation increases when the evaporation contribution from the south is enhanced while heavy precipitation increases when the evaporation contribution from the northeast is enhanced in the PRD. The precipitationshed is influenced by natural climate variability. The identified differences in the response of different types of precipitation to the change in the precipitationshed further help us to better understand the influence of natural climate variability on precipitation. The influences of El Nino Southern Oscillation (ENSO), Indian Ocean Dipole (IOD), and North Atlantic Oscillation on different types of seasonal precipitation were investigated. For example, results show that more heavy precipitation is expected in the PRD in summer when the positive phase of IOD and the negative phase of ENSO occur simultaneously.