低纬环流系统对江淮梅雨暴雨影响的数值模拟

NUMERICAL STUDY OF INFLUENCE OF LOW-LATITUDE CIRCULAT MEIYU-SEASON TORRENTIAL RAINFALL OVER CHANGJIANG-HUAIHE RIVER CATCHMENT

利用有限区域细网格模式与Ｔ＿（４２）Ｌ＿９谱模式进行三维嵌套，对１９９１年７月１０～１１日０８时江淮梅雨暴雨过程作了数值模拟，探讨了低纬环流系统和由其形成的水汽输送通道对江淮梅雨的影响。结果表明：孟加拉湾水汽源地及其西南季风水汽输送通道的贡献大于南海水汽源地及其东南季风水汽输送通道；两个水汽源同时存在，对江淮梅雨暴雨引起非线性叠加增强；台风环流和季风低压环流强度的变化对江淮梅雨暴雨有重要作用。

Through 3D nesting of a limited-area fine-mesh model and a T_(42) L_9 spectral model,nu-merical study is undertaken of Meiyu-season torrential rainfall over the Changjiang-Huaihe rivercatchment from 0800 BST,10 to 0800,11 July,1991,with the influence of the low-latitude circu-lation systems and the related vapor passage on the Meiyu precipitation investigated.Results showthat the Bay of Bengal water source and the SW monsoon-formed passage contribute more greatlythan do the source of the South-China Sea and the SE wind-caused passage;both the sources,if-coexistent,produce nonlinear superimpositional effects,causing the enhancement of the rainfall;the change in the vigor of the typhoon and monsoon depression circulations is of importance tothe formation of the torrential rainfall as well.