9106号台风的热力作用对出梅影响的数值研究

A NUMERICAL STUDY OF HEAT EFFECT OF TYPHOON 9106 ON MEIYU ENDING

利用一个五层的原始方程模式，研究了９１０６号南海台风的热力作用对１９９１年江淮梅雨的影响，数值试验结果表明，这次台风活动对１９９１年梅雨提前结束起了很大的作用。其影响的物理机制可归纳为：台风扰动热源在对流层激发出的水平流场，减弱了西南季风及其向江淮流域的水汽输送，使江淮流域的水汽通量辐合减小，影响东亚夏季风的经向垂直环流圈，抑制了江淮流域梅雨期的季风环流，促使西太平洋副高北跳，使梅雨结束。

Using a five-layer primitive equations model,Typhoon 9106 in the South China Sea is investigated in terms of its thermodynamic effect on the 1991 Meiyu process over the area of so-called Yangtze-Huaihe-River Basin. Numerical experiments show that the typhoon contributes much to the earlier-than-usual ending of the Meiyu in 1991, mainly through physical mechanisms of (1) horizontal tropospheric flow fields excited by heation source of typhoon disturbance, which weakens Southwest Monsoon transporting moisture to the basin, resulting in less convergence of moisture flux; (2) meridional vertical circulation cell affecting summer monsoon in East Asia,which inhibites monsoon circulation during the Meiyu period; and (3) the subtropical high in West Pacific, which is pushed northward by the storm to end the Meiyu.