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

Using the meteorological data at 97stations in Hunan from 1952to 2010and NCEP reanalysis data,and statistical analysis and other methods,the spatial and temporal distributions of the heavy rainstorm in Hunan were analyzed.The result shows that the station number in rainstorm process of Hunan in the past 59years appears increasing trend,the heavy rainstorm processes over the years are total 376times,which mainly occurs in the main flood seasons(from June to August),accounts for 70.7%,and the peak is in June.The longest process of heavy rainstorm is 6days,79%is about 2days.The prone frequency areas of heavy rainstorm mainly located in western and northern Hunan,but south-western Hunan,some counties of Chenzhou,most counties of Changsha and Loudi are the less prone areas.Through the analysis of the circulation characteristics in 376rainstorm weather processes,5types of weather system typing with trough+shear+frontal type,low vortex shear+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 forecast.