Interdecadal Variability of Spring Precipitation over South China and Its Associated Atmospheric Water Vapor Transport

Abstract

The characteristics of spring precipitation and water vapor transport in South China were analyzed by using observational data and the National Centers for En- vironmental Prediction (NCEP) reanalysis data. The re- sults show that, during the spring, each component of the water cycle (precipitation, wind field, specific humidity, water vapor transport, etc.) in South China exhibits a no- table interdecadal variability. An abrupt increase in spring precipitation occurred in the early 1970s. During the dry period from 1958 to 1971, a water vapor flux divergence (positive divQ) existed in South China, which may have led to the deficiency in rainfall. However, during the wet period from 1973 to 1989, there was a remarkable water vapor flux convergence (negative divQ) in South China, which may have resulted in the higher rainfall. The inter- decadal variability of water vapor transport is closely re- lated to the interdecadal variability of wind fields, al- though the interdecadal variability of specific humidity also plays a role to some extent, and the interdecadal variability of the zonal water vapor transport contributes much more to the interdecadal variability of spring pre- cipitation than the meridional water vapor transport.