Possible Relationships Among South China Sea SSTA, Soil Moisture Anomalies In Southwest China And Summer Precipitation In Eastern China

By using1958-2001NOAA extended reconstructed SST data, ERA40reanalysis soil moisture data and precipitation data of444stations in China (east of100°E), the possible relationships among South China Sea SSTA, soil moisture anomalies and summer precipitation in eastern China as well as their possible physical processes are investigated. The main conclusions are summarized as follows:The early spring South China Sea SST bears a significant correlation with the late spring soil moisture in China, and the correlation varies by region. Through the analysis we found that the spring SST bears a positive correlation with the spring soil moisture in the Southern China, a negative correlation in the Yangtze River Basin, a positive correlation in the Northern China and a negative correlation in the Northeast. The most significant negative correlation appears in the eastern Southwest China.Late spring soil moisture index of the eastern Southwest China has significant inter-annual changes, and the soil in eastern Southwest China is general drying trend. Before the end of1970s, the soil moisture in eastern Southwest China is often high, and it is often low after the end of1970s.South China Sea SSTA bears a very significant negative correlation with spring soil moisture in the eastern Southwest China. The correlation coefficient of the two indexes is up to-0.52.More (less) precipitation happens in the Yangtze River Basin and less (more) in the Southeast China in summer when the South China Sea SST is higher (lower) than normal and the soil moisture in the eastern Southwest China is dry (wet) in spring.Further analysis shows that when South China Sea SST is higher (lower), the southwest wind at low level is weak (strong), decreasing (increasing) the water vapor transport in South China, resulting in reduced (increased) spring precipitation in eastern Southwest China, so the soil moisture in spring is low (high).Through the evaporation mechanism, the dry (wet) soil makes the surface temperature higher (lower) in summer, causing the westward extension (east back) of the West Pacific Sub-tropic High, eventually leading to the summer precipitation anomalies.