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Using the regional climate model RegCM4.4.5, coupled with the land model CLM4.5, we investigated the effects of springtime soil moisture in the Indochina Peninsula on summer precipitation over the South China Sea and its surrounding areas in 1999. Results have indicated that there exists positive correlation between soil moisture and summer precipitation over the western Pacific Ocean and negative correlation between soil moisture and summer precipitation over the eastern Indian Ocean. Summer precipitation in the South China Sea and its surrounding areas responds to springtime soil moisture in the Indochina Peninsula(the northwest region is critical) because general atmospheric circulation is sensitive to the near-surface thermodynamic state. Increased(decreased) soil moisture would result in decreased(increased) local surface temperatures. Latitudinal, small-scale land-sea thermal differences would then result in northeasterly wind(southwesterly wind) anomalies in the upper layer and southwesterly wind(northeasterly wind) anomalies in the lower layer, which strengthen(weaken) monsoon development. As a result,precipitation would enter the Western Pacific region earlier(later), and water vapor over the eastern Indian Ocean would enter the South China Sea earlier(later), causing a precipitation reduction(increase) in the eastern Indian Ocean and increase(reduction) in the Western Pacific. [ABSTRACT FROM AUTHOR]