Abnomity Of The Atmospheric Circulation And Its Relationships To Rainfall In 2003 And 1999

The summer weather in China from 1999 to 2004 appeared abnormal again in 2003 and 1999 after the severe flood in Yangtse river basin and Nen-Jiang river vally in 1998. There was an abnormity that the warm over large area in China, the drought over most area in North of China, the more rainfall in South of China , and the less rainfall in North of China ocured in the summer in 1999. The characteristic that the extreme high temperature over large area in South of Yangtse river basin and the long time maintained rainfall zone in Huai-He river vally presented was extreme in the history. Therefore, used the sea level pressure (SLP) which was adopted less in the past research, this paper investigated the correlation between the SLP and the summer rainfall in East of China by SVD and correlation analysis. The results from our research showed as the followings:1) There were most significant positive assosiactions between the rainfall over Jiang-Huai area in the summer in 2003 and the SLP during the same time in tropical western Pacific and that in the area around Huang-Hai Sea and Bo-Hai Sea. The former showed a positive correlation, while the latter showed a significant negative correlation. When the SLP in tropical western Pacific was higher, the subtropical anticyclone moved westen and southern and the rainfall over Jiang-Huai area become more. When the SLP in the area around Huang-Hai Sea and Bo-Hai Sea was lower, the pressure near Bo-Hai Sea become lower, the trough and the activity of the northern cold air strengthened, and the rainfall over Yangtze river basin also become more. When the former was lower and the latter was higher, the subtropical anticyclone moved westen and southern and the rainfall over Jiang-Huai area become more, the trough near Bo-Hai Sea strengthened, the wind converged in Yangtse river basin, and the rainfall over Yangtse river basin become more. In addiction, the joint action of these two factors can denote the rainfall over Yangtze river basin better.2) The correlations between the rainfall over Jiang-Huai area in the summer in 1999 and the SLP during the same time in tropical western Pacific and that in Sebaria area were most significant. The former presented a positive correlation, while the latter presented a significant negative correlation. When the SLP in tropical western Pacific was higher, the subtropical anticyclone was more southern and the rainfall over Jiang-Huai area become more. When the SLP in Sibaria area was lower, the Asian polar vortex become stronger, the massive northern cold air gone down southern, and the rainfall over Yangtze river basin also become more. When the former was lower and the latter was higher, the subtropical anticyclone was more southern, the activity of the northern cold air strengthened, and the rainfall over Yangtze river basin become more.3) Analyzed the relationship between the SLP and the low frequent atmospheric circulation of 3~10 days, 10~20 days, and 20~50 days, it was found that the correlation between the SLP and the low frequent atmospheric circulation of 20~50 days was best.