长江上游秋季降雨特征及主要影响天气系统分析

Autumn rainfall features and main influencing meteorological influence system analysis in upper Yangtze River

分析长江上游秋季降雨特征及其影响系统,对于开展长江上游秋汛期降雨预报有重要指导意义。选用1951～2009年长江上游各区面雨量资料,重点对该期间秋季的长江上游降雨时空分布以及形成秋季降水的成因进行了分析探讨。得出的初步结论是:长江上游面雨量,多年在800～1 000 mm之间变化;9月份,上游偏北偏西地区降雨量较大;10月份以后,上游偏南偏东地区降雨量较大。长江上游秋季的连续阴雨天气,往往与稳定的环流形势、高空槽、地面锋的影响有关,而强降雨的发生,除需具备这些条件外,还与低涡、切变线的影响有关。

Selecting the area rainfall data of 1951～2009 of several zones in upper Yangtze River,we mainly discuss the distribution laws of autumn rainfall and carry out a cause analysis.The preliminary results show that the precipitation of area rainfall in autumn ranges from 800～1000 mm;in September,the precipitation in the west and north area shows a larger amount than other parts;after October,the higher-rainfall area tends to move to south and east area.The presented continuous rainfall weather in autumn of upper Yangtze River usually is bonded up with a stable atmospheric circulation pattern,upper trough,surface front,besides these necessary conditions,vortex and shear line are also involved.