4—6月江淮流域不同尺度温带气旋发展率及移动特征

基于改进的温带气旋客观识别方法,统计分析1986—2015年4—6月不同空间尺度江淮流域温带气旋的发展率及移动特征。结果表明:1)整体气旋发展率呈先上升、后下降趋势,较大空间尺度气旋发展率呈显著上升趋势,中间尺度气旋发展率无明显变化趋势。2)较大尺度气旋源地集中在湖北、湖南交界处,中间尺度气旋源地位于安徽等江淮流域东部,各尺度气旋源地位于整层大气非绝热加热项大值区域内。3)气旋初生阶段,江淮流域存在风速切变线,淮北地区风速小于淮南地区,江淮流域上空对流层低层位势高度为负距平,中高层则为正距平,属浅薄低压系统。4)不论何种尺度气旋,均存在东移和东北移动路径,但较大尺度气旋东北移动路径的比例较大。

Development rate and movement characteristics of extratropical cyclones at different scales in the Changjiang-Huaihe River Valley from April to June

Based on the improved objective identification method of extratropical cyclones,this paper investigated the development rate and movement characteristics of extratropical cyclones at different scales in the Changjiang-Huaihe River Valley (CHRV) from April to June during 1986-2015.Results show that the overall cyclone development rate shows an upward trend first and then a downward trend,the larger spatial scale cyclone development rate shows a significant upward trend,and the middle scale cyclone development rate has no obvious change trend.The larger scale cyclone sources are concentrated at the junction of Hubei Province and Hunan Province.The middle scale cyclone sources are located in the eastern part of CHRV,such as Anhui Province.The sources of cyclones at different scales are located in the large value region of the non-adiabatic heating term in the whole atmosphere.During the initial stage of cyclone,there is a wind shear line in the CHRV.The wind speed in the northern CHRV is smaller than that in the southern CHRV.The geopotential height anomaly is negative in the lower troposphere and positive in the middle and upper troposphere over the CHRV,which belongs to a shallow low pressure system.All scale cyclones have east-moving and northeast-moving paths,but the larger scale cyclones have a larger proportion of northeast-moving path.