The Characteristics of Frontal Precipitation in South China During the Pre-Rainy Season and Its Response to Indian Ocean Sea Surface Temperature Anomalies
ZENG Weijie
WANG Lijuan
BAO Ruijuan
Abstract：Using daily precipitation data,ERA5 reanalysis data and NOAA monthly sea surface temperature(SST)data from 1991 to 2020,we employed Empirical Orthogonal Function(EOF)analysis and water vapor budget diagnostics to investigate the characteristics of frontal precipitation in South China during the pre-rainy season(FRSCPS)and its response to Indian Ocean SST anomalies.The results indicate that the leading spatial mode of FRSCPS is characterized by a regionally coherent pattern across South China.During flood years,the Western Pacific Subtropical High shifts westward,accompanied by an anomalous cyclone in the lower troposphere.This configuration induces air mass convergence,enhances upward motion,and promotes anomalous moisture flux convergence,which increases precipitation.The circulation during drought years exhibits opposite patterns.The abnormal FRSCPS is primarily influenced by two dynamic factors:changes in moisture advection and the dynamic contribution from wind field convergence and divergence,with the latter playing a dominant role.Meridional moisture transport in the lower troposphere is crucial for FRSCPS.Positive SST anomalies in the Indian Ocean key regions(80-108°E,12°S-14°N)excite eastward propagation Kelvin waves by triggering atmosphere heating via latent heat release from condensation,leading to an anomalous anticyclonic in the lower troposphere over the South China Sea-Western Pacific region,thereby enhancing the meridional moisture transport to South China and increasing precipitation.
Keywords：South China pre-rainy seasonfrontal precipitationwater vapor budgetatmospheric circula-tionIndian Ocean sea surface temperature
Publication Date：2025-08-30
Online Publishing Date：2025-09-23(First online date of this platform, not the publication date of the document)
Pages：9( 566-574 )