2013年12月中旬江西一次冬季暴雨过程诊断分析

Diagnostic Analysis on the Rainstorm Process in the Winter of 2013 in Jiangxi Province

利用常规观测资料和NCEP逐6 h的1°×1°再分析资料,对2013年12月15—17日江西冬季最强连续暴雨天气过程进行诊断分析。结果表明:1)暴雨过程是由于南支槽位于大陆高压和副热带高压之间,西风气流强度弱和副热带高压的阻挡作用导致槽移动缓慢,长时间滞留导致槽前西南气流沿低层锋区爬坡而形成的。2)冬季暴雨的产生与充沛的水汽输送、较强的辐合上升运动、较长的持续时间密切相关,且与700 h Pa高度层上的水汽、动力等条件联系更紧密。3)相比一般汛期暴雨过程,冬季暴雨过程中比湿、K指数等明显偏小,大气层结比汛期暴雨要稳定得多,但该次暴雨过程在垂直速度、散度、水汽输送条件非常接近汛期暴雨相关指标。

Based on the Automatic weather station data（AWS）,convection observational data and the FNL（1°×1°）reanalysis data,the characteristics of a rainstorm process were analyzed in south-central Jiangxi from December 15 to 17,2013. The results showed that the south branch trough was located between the continental high and the Pacific subtropical high. The south branch trough moved slowly because of the weak westerly flow and subtropical high blocking. The stable southwesterly flow of high-level trough climbed along the low-level frontal zone,which was an important reason for the persistence of precipitation. The rainstorm process was closely related to the abundant water vapor transportation,strong convergence ascending motion and long duration,and was more closely related to the water vapor condition and dynamic condition at 700 h Pa. Compared with the rainstorm process in the flood season,the specific humidity,K index were apparently smaller in winter rainstorm process,also the atmosphere condition was much more stable. However,during this process,which was the strongest rainstorm process in winter over the past years,the vertical velocity,divergence and water vapor conditions in the heavy rain process were closely to the flood season rainstorm.