江西持续性强降雨的气候特征及其大尺度环流背景

利用1961-2010年江西省83个常规气象观测站的逐日降水资料,对江西省持续性强降雨进行了统计分析,结果表明:1961-2010年江西省共出现了82次持续性强降雨过程,且持续性强降雨有着显著的季节变化、年际变化和年代际变化特征,其季节变化以6月最多,冬季(12-2月)无持续性强降雨,年际变化主要有3 a左右和6～8a的变化周期.年代际变化周期主要为30 a左右的变化周期,且在2000年后减小为25 a左右.江西省持续性强降雨累积日空间分布不均,具有南北少中间多的特征,多发区位于江西东部的浙赣铁路沿线.对持续性强降雨对应的大尺度背景环流形势分析发现,大尺度背景环流形势主要有4种:低槽型,南槽北脊型,台风型和转换型.其中低槽型出现的次数最多(34次),台风型出现的次数最少(9次),转换型的持续时间最长.

Climatic characteristics of persistent heavy rains over Jiangxi and their large scale circulation backgrounds

With the daily precipitation datasets at 83 stations in Jiangxi from 1961 to 2010, the variations and characteristics of persistent heavy rain are analyzed. The results show that there are 82 times of persistent heavy rain processes which have significant seasonal and annual variations in Jiangxi. They mostly distribute in June, but none of them occurs in winter. It has two inter-annual variation periods of about 3 a and 6 to 8 a, and an inter-decadal variation period of about 30 a, which has been decreasing to 25 a since 2000. There is uneven spatial distribution of persistent heavy rain, which is more in middle of Jiangxi and less in south and north. Large scale weather patterns of the persistent heavy rain in Jiangxi can mainly be classified into 4 sorts: trough pattern, south trough north ridge pattern, typhoon pattern, and transition pattern, in which, trough pattern is 34 times (the most), typhoon pattern is 9 times (the least), and transition pattern has the longest duration.