The Influences Of Triple And Dipole SSTA Patterns In Equatorial Pacific On Summer Climate Of China And The Research On Its Mechanism

Using the monthly mean SST data from HadISST, reanalysis data and precipitation and temperature data from Chinese 160 stations, we investigate the different influences of "triple pattern" SSTA and "dipole pattern" SSTA in equatorial Pacific on summertime rainfall and temperature in China. We also analyze the sensitivity of summer rainfall areas to tropical ocean SSTA. The results are summarized as follows:(1) Both "triple pattern" and "dipole pattern" SSTA have a distinct impact on summertime rainfall and temperature in China, but the influences between the two patterns are very different. The obvious impact of "Triple pattern" SSTA on summer climate in China is observed in the east part of northwest area, Huaihe river valley and south part of China. In the month of positive SSTA of central tropical Pacific, less summer rainfall and high temperature is received in the east part of northwest area and Huaihe river valley, but the opposite scenario is showed in south part of China. Eddy source induced by "Triple pattern" SSTA rouses cyclonic circulation at 850hPa in South Ocean. This cyclonic circulation weakens the moisture transfer from South Ocean to north part of China. So flood events are observed in the south part of China and drought events are received in Huaihe river valley. However, during the month of negative SSTA of central tropical Pacific, the scenarios of the rainfall and temperature anomalies as mentioned above seem to be oppositely signed in those regions.The obvious impact of "dipole pattern" SSTA on summer climate in China is observed in Hetao area and Huaihe river valley. In the month of positive SSTA of east tropical Pacific, more precipitation is received in Hetao area. However in the reach of Huaihe river rainfall tends to be less than normal. Low air temperature is dominated in most part of China. According to above mentioned, the influences of "dipole pattern" SSTA on summertime climate is opposite to "triple pattern" SSTA, particularly in Huaihe river valley.(2) Three areas in global Tropical Ocean, which are east tropical Pacific, Indian Tropical Ocean and Atlantic Tropical Ocean, have evident effects on summertime precipitation in China. But these three areas have different influences on summer rainfall in China. Abnormal rainfall in reach of Huaihe River and north part of China is mainly induced by east Pacific SSTA. However, Indian Ocean SSTA usually leads to abnormal rainfall in south of Yangtze River and the relationship between the two is positive. The scenarios induced by Atlantic Ocean are similar to those induced by Indian Ocean.