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本文通过调查1951-2007年发生的多次ENSO事件的太平洋海表面温度变化情况将其分为四种类型,分析这四种事件在不同阶段的夏季环流形势和850h Pa风场,从而讨论西太平洋副热带高压(以下简称副高)和夏季风对长江流域夏季降水情况的影响,结果表明:不同类型的El Ni?o和La Ni?a事件与夏季副高强度、西伸脊点以及脊线位置关系密切,且影响夏季风的强弱变化。东部型El Ni?o主要是副高的变化影响降水,而中部型事件则是通过风场响应来影响降水的变化,且两类事件中雨带都有从长江以北到长江中下游偏南地区的移动过程;东部型La Ni?a时期副高显著减弱东退,使长江流域降水量减少,中部型La Ni?a在发展年因为副高脊线北抬,长江以北出现雨带,在消退年因为副高有北抬且长江中下游有偏南风的风速辐合带,东南地区偏南风加强,有两个雨带分别位于黄河-长江中下游和长江以南。
In this paper, we investigate the summer circulation and the wind field at 850hPa during different stages of the four events by investigating the variations of Pacific sea surface temperature over the many ENSO events that occurred from 1951 to 2007, Subtropical high (hereinafter referred to as the subtropical high) and the summer monsoon on the summer precipitation in the Yangtze River Basin, the results show that: the different types of El Niño and La Ni? A events and summer subtropical high, west stretch ridge and ridge position Closely related, and affect the strength of the summer monsoon changes. The eastern El Niño is mainly due to the variation of the subtropical high that affects precipitation, while the middle-type event affects the precipitation through the response of the wind farm. Both types of events have rain belts from the north of the Yangtze River to the middle and lower reaches of the Yangtze River During the Eastern La Niña period, the subtropical high retreated eastward significantly, which led to the decrease of precipitation in the Yangtze River Basin. Because of the northward elevation of the subtropical ridge and the rain belt north of the Yangtze River, In the subsided year, the southerly wind intensifies in the southeastern part because of the windward convergence of the southerly winds in the middle and lower reaches of the Yangtze River due to the elevation of the subtropical high in the north and two rain belts in the middle and lower reaches of the Yangtze River and south of the Yangtze River respectively.