春季江淮气旋及影响的统计分析

以Lu1]改进的温带气旋识别方法为基础,结合江苏省73个人工气象观测站的降水资料,统计分析了近35年来春季江淮气旋及其与江苏春季暴雨的关系。结果表明,近35年来,春季江淮气旋发生的次数呈现趋势性递减的变化,其源地主要集中在安徽西南部的大别山东侧和西北部的淮河上游平原。江淮气旋对沿江苏南的春季暴雨有重要影响,而对淮北地区暴雨的影响最弱,给江苏春季带来区域性暴雨的江淮气旋主要是介于中尺度和天气尺度之间的次天气尺度系统。引起淮北和江淮之间两个区域暴雨的江淮气旋源于皖、豫、鲁三省交界处的比例较高。春季江淮气旋造成的暴雨区主要位于气旋中心附近和气旋的南部。其中,淮北地区雨区主要位于气旋中心附近,沿江苏南的雨区在气旋中心和南部均有分布。气旋中心涡度和风速大小、低空西南急流的位置和水汽通量辐合的位置是暴雨落区差异的主要原因。

Statistical Analysis of Jiang-huai Cyclone and Its Influence in Spring

Based on improved method of identification of extratropical cyclone by Lu1]and precipitation data of 73 meteorological stations in Jiangsu province,this paper analyzes the Jiang-huai cyclone in spring and its impact on heavy and torrential rains in Jiangsu in the past 35 years.The results show that the number of Jiang-huai cyclone has decreased in spring during the past 35 years.The sources of Jiang-huai cyclone are mainly concentrated in the eastern side of Dabie Mountain in southwestern Anhui and the upper Huaihe River plain in northwestern Anhui.The Jiang-huai cyclone has a significant influence on spring heavy rain in the south of Jiangsu along the Yangtze River,but a weak effect on the rain in the north of Huaihe River.The Jiang-huai cyclone,causing regional heavy rain in Jiangsu,is a sub-synoptic scale system between meso-scale and synoptic scale.The high proportion of the Jiang-huai cyclone responsible for the spring heavy rain in the north of the Yangtze River is originated from the junction of Anhui,Henan and Shandong provinces.The torrential rain areas in Jiangsu are mainly located near the cyclone center and the southern part of the cyclone in spring.The heavy rain in the north of Huaihe River is distributed mainly near the cyclone center,while heavy rain in the south of Jiangsu along the Yangtze River is distributed in both the cyclone center and the south of the cyclone.The central vorticity and wind speed of the cyclone,the position of the low-level southwest jet and the convergence area of water vapor flux are the main reasons for the location difference of heavy rains.