The Relationship Between Summer Precipitation In Eastern China And Thermal Variation Of East China Sea And Its Adjacent Seas

The relationship between the interannual variations of summer precipitation in eastern of China and the SST anomalies in East China Seas and their adjacent seas is analysed by using the methods of composite and correlation analyses and the daily data of summer (June-August) precipitation at 752 stations of China, GPCP 2.1 and HadISST datasets from 1979 to 2008. A regional climate model(RegCM3) is then used to simulate these relations. The results show as follow:(1) Observation data analysis results indicate that when SST of East China Seas and their adjacent seas is in warm (cold) anomalies in summer, there are less (more) rainfall in middle and lower reaches of the Yangtze River and the Yangtze River/Huaihe River valley(Jianghuai valley) and the more (less) rainfall in the southern part of Northeast China.(2) The simulated results indicate that the warm (cold)SST anomalies in East China Seas and their adjacent seas can contribute to the less (more) rainfall in the middle and lower reaches of the Yangtze River and the Yangtze River/Huaihe River valley (Jianghuai valley) and most of North China and more (less) precipitation in South China, southeast part of Northeast China and the Korean Peninsula.(3) The processes of atmospheric circulation variability over East Asia caused by the SST anomalies in these sea regions explored based on the NCEP/NCAR reanalysis and numerical simulation. The result shows that increase or decrease of SST in the above-mentioned seas has remarkable effect on zonal and meridional circulations over East Asia. When SST of East China Seas and their adjacent seas is above normal, a downward motion with a divergence in low level and a convergence in upper level can appear over the middle and lower reaches of the Yangtze Rive and the Yangtze River/Huaihe River valley(Jianghuai valley) and most of North China, which contributes to the decrease of summer rainfall in these areas, in addition to an upward motion with a strong convergence in low level and a remarkable divergence in upper level can be caused over the region to the east of these seas. And a upward motion with strong convergence in low level and remarkable divergence in upper level is caused in South China, southern part of Northeast China and the Korean Peninsula, thus, the summer precipitation increase obviously in these regions. Consequently, it is suggested that the thermal state of the East China Seas and their adjacent seas maybe one of the important factors affecting the summer precipitation in East China.