Spatial Patterns Of SSTA In Western Pacific Warm Pool Region And Its Relations To Summer Rainfall In China

Based on the SST data, the temporal and spatial variations of SSTA in Western Pacific Warm Pool region have been analyzed in this paper by means of EOF. Results show that there are two main spatial patterns of the WP SSTA: one is uniform in the whole area, the other is of the north-south asymmetry.When the spatial pattern is uniform in the whole area, in the warm years, there is a anticyclone circulation existing over the warm pool and westerly in the subtropical region and easterly in the tropical region have been greatly strengthened at 850hPa, while a anticyclone circulation over the India Region at 200hPa, the Walker circulation has been strengthened, the summer rainfall may be above normal in the upper and middle reaches of the Yangtze River, vice versa.When the spatial pattern is of the north-south asymmetry, in the warm north-cold south years, there is a anticyclone circulation existing over the warm pool at 850hPa, easterly at 15 N and westerly in the tropical region have been greatly strengthened, while the center of anticyclone circulation moves to the East Asia at 200hPa, and the Hadley circulation has been affected evidently, so the summer rainfall may be above normal in the middle and lower reaches of the Yangtze River, vice versa.There are different relations to East Asia atmospheric circulation and summer rainfall in China. When the spatial pattern is uniform in the whole area, there is a better relations between the WP SSTA and Walker circulation, Hadley circulation, ENSO and the summer rainfall of the upper and middle reaches of the Yangtze River, while the spatial pattern is of the north-south asymmetry, there is a better relation between the WP SSTA and Hadley circulation and the summer rainfall of the middle and lower reaches of the Yangtze River.