丹江口水库流域秋季连阴雨中一场暴雨的成因分析

Analysis on Causes of a Rainstorm during Continuous Autumn Rain in the Danjiangkou Reservoir Basin

摘要: 利用常规天气资料、地面降雨量资料、FNL资料与卫星云图资料，对2014年9月17~18日丹江口水库流域的一次秋季连阴雨中的暴雨过程进行了诊断分析，结果表明：高空低槽、中低空切变线与地面东路冷空气是暴雨发生的主要影响系统；秋季连阴雨中的暴雨与夏季暴雨明显不同，即暴雨发生在稳定的大气层结状态下，卫星云图显示，降雨云系以层状云为主，部分时段出现了弱的对流云系，但较夏季要弱的多；中低空暖湿急流一方面为暴雨提供了源源不断水汽条件，另一方面与低层冷空气在丹江口水库流域形成了较强的锋区，暴雨发生在锋区中水汽辐合较强的区域。

Abstract: In order to improve the forecasting accuracy of this kind of weather, the rainstorm process during continuous autumn rain on Sept. 17~18, 2014 in the Danjiang Reservoir basin was analyzed by using conventional meteorological and rainfall date, FNL date, satellite cloud pictures and so on. The results show that: the main affecting systems of rainstorm come from the low trough of upper air, middle and low level shear line and the cold air from the east area. The rainstorm during the continuous autumn rain is obviously different from that in summertime that stability of atmospheric stratification occurs. The satellite images show that the precipitation cloud system is mainly stratiform cloud, and there are convective clouds in some period, but considerably weaker than those in summertime. The wet and warm of middle and lower tropospheric jets provide abundant moisture for the rainstorm, and it forms strong frontal zone with cold air at the lower troposphere in the Danjiangkou Reservoir basin. Rainstorm occurs in the frontal zone where the water vapor convergence is stronger.