川西南地区大暴雨气候特征分析

The Heavy Rainstorm Climate Characteristic Analysis in Southwest Sichuan

本文用1958～2010年53年的乐山、眉山、雅安三市大暴雨降水资料,从气候趋势、时空分布等方面分析了川西大暴雨的气候变化特征：1）53年内盆地西南的大暴雨主要分布在雅安东北、眉山西南、乐山西北部地区,在该区域形成一暴雨中心圈;2）大暴雨发生次数在洪雅、峨嵋、夹江、天全等地有减少趋势;而在雅安、青神、沐川则有增强趋势;3）雅安和乐山两地大暴雨次数历年分布有一定的同步性,眉山的大暴雨次数分布和雅、乐两地的关联不明显;4）三地大暴雨分布的主要特征形态为以雅安、名山、洪雅、峨嵋为中心区域的一致性分布为主;第二种主要分布形态为雅安和峨嵋两个中心的反相关状态.此外,对历史上两次特大暴雨的天气形势进行分析,揭示特大暴雨发生的背景和条件.

By using 53 years＇ heavy rain storms data in Leshan, Meishan and Ya＇ an from year 1958 to 2010, climate trend analysis method, temporal distribution and spatial distribution of heavy rainstorms in southwest Sichuan region are studted. Resuhs show： 1 ） The main heavy rain storms happened in northeast of Ya＇ an, Southwest Meishan and Northwest Leshan in 53 years and made that region to be the center of heavy rain storms. 2） The happening times of heavy rain storms are going down in Hongya, E＇ met, Jiajiang and Tianquan region. But the happening times in Ya＇ an, Qingshen and Mechuan are going up in Ya＇an, Qingshen and Muchuan region at the same period. 3） The happening times of heavy rain storms in Ya＇an and l,eshan distribution are consistent with each other. The happening times of heavy rain storms in Meishan had little relationship with Ya＇ an and l~,shan area. 4） The main distribution characteristic of heavry rain storms in three regions is accordant and has a central area in Ya＇ an, Mingshan, Hongya and E＇ met. The second distribution characteristic of the hearty rain storms is the opposite relevant status in Ya＇ an and E＇ mei. The synoptic analysis of two historic heavy rain storm processes are carried and the weather background and condition of heavy rain storms are revealed.