湖南省大暴雨时空分布特征及其分型

Characteristics of Temporal-Spatial Distributions of Heavy Rainstorm in Hunan and Its Typing

利用1952-2010年湖南97个测站常规观测资料和NCEP 1°×1°再分析资料,采用统计分析等方法,分析了湖南大暴雨的时空分布特征。结果表明,近59年来湖南大暴雨站次和过程次数均呈增加趋势,历年大暴雨过程累计376次,主要发生在主汛期(6-8月),占全年累计总数的70.7%,且以6月出现最多;大暴雨天气过程最长持续时间为6天,79%的过程为2天左右;大暴雨多发区主要位于湘西、湘北,而湘西南、郴州部分县市、长沙以及娄底大部分县市为少发区;通过对376次大暴雨天气过程高低空环流形势特征分析,建立了5类天气学分型,即低槽+切变+锋面型、低涡切变+锋面型、副热带高压边缘型、热带低压型(包括台风、低压和热带辐合)、东风带系统型。T639L60模式的物理量场分析表明,大暴雨与不同层次的垂直速度、涡度、散度场、水汽通量和低层的水汽通量散度、比湿、K指数及θse关系密切。

Using the meteorological data at 97 stations in Hunan from 1952 to 2010 and NCEP reanalysis data, and statistical analysis and other methods, the spatial and temporal distributions of the heavy rain- storm in Hunan were analyzed. The result shows that the station number in rainstorm process of Hunan in the past 59 years appears increasing trend, the heavy rainstorm processes over the years are total 376 times, which mainly occurs in the main flood seasons （from June to August）, accounts for 70.7o//00, and the peak is in June. The longest process of heavy rainstorm is 6 days, 79% is about 2 days. The prone fre- quency areas of heavy rainstorm mainly located in western and northern Hunan, but south-western Hu- nan, some counties of Chenzhou, most counties of Changsha and Loudi are the less prone areas. Through the analysis of the circulation characteristics in 376 rainstorm weather processes, 5 types of weather system typing with trough q- shear q- frontal type, low vortex shear q- frontal type, subtropical high edge type, tropical depression type （including typhoon, low and tropical convergence）, and easterlies with type are established. The objective quantitative factor closely with heavy rainstorm are statistically analyzed based on the physical quantity field of T639L60, which summed up the eight weather models, and building the heavy rainstorm forecasting conceptual model which include high and low air circulation configurations, power, thermal conditions and heavy rainstorm areas, etc. provid the reference for heavy rainstorm fore- cast.