Generral Circulation over Northern Hemisphere in 1997 and Their Impact
General circulation featrues over the Northern Hemisphere in 1997 are analysed. It is shown that the subtropical high over the west Pacific turns stronger,and extends to the west,and at the same time moves northward in the midsummer. At 500hPa,zonal circulation is dominant in the middle latitude of Asia in the most time of the year. Meridinal circulation strengthen during the spring and autumn. Cold air is weaker than normal during the winter and summer. Monsoon over the South China Sea is stronger than normal,monsoon over India is weaker than normal in the midsummer. ITCZ over the west Pacific is werker than normal. At 100hPa,the geopotential height at the mid low latitude is above normal. The location of the South Asia High is farther to the east than normal. A new El Nino event took place in the tropical Pacific region in 1997. the anomaly of both the tropical Pacific and atmosphere circulation exerted a significant impact on the weather and climate in China.