年西南涡年际变化特征及夏季环境场异常  

Interannual Variation Characteristics and Summer Environmental Field Anomalies of Southwest Vortex during 1979-2020

作　　者：李更小 冯鑫媛 王一行 LI Gengxiao;FENG Xinyuan;WANG Yixing(College of Atmospheric Science,Chengdu University of Information Technology,Plateau Atmosphere and Environment Sichuan Province,Chengdu 610225,China)

机构地区：[1]成都信息工程大学大气科学学院/高原大气与环境四川省重点实验室,四川成都610225

出　　处：《成都信息工程大学学报》2025年第2期201-211,共11页Journal of Chengdu University of Information Technology

基　　金：国家自然科学基金资助项目(U2242202)。

摘　　要：利用CFSR再分析资料,对1979-2020年的西南涡进行统计分析,然后利用合成分析等方法对夏季(6-8月)西南涡异常的环境场进行研究,由此得到近42年来西南涡年际变化的基本特征和有利于夏季西南涡形成的环境因素。结果表明:近42年来西南涡共计3078例,平均每年73.3例。春夏多,秋冬少。夏季出现频率呈减少趋势,冬季呈增长趋势,其余两季变化不明显。西南涡平均生命期为15.9h,平均水平尺度可达419.4km。西南涡的持续时间和强度在42年间有增长趋势,水平尺度则呈下降趋势。高层高空急流偏南偏东,南亚高压强度偏弱时有利于夏季西南涡的形成。中低层高原南北两侧和贝加尔湖及东海以东“北低南高”和“东高西低”的位势高度分布有利于高原东侧西南气流加强及高原南侧西风维持,由此形成的气旋性切变为西南涡的形成提供了良好的条件。冷暖平流分布不均,温度场及湿度场“上暖下冷,上湿下干”的不稳定分布也有利于西南涡的形成。850hPa孟加拉湾一南海一四川盆地的水汽输送通道也为西南涡的形成创造了良好的水汽条件。Based on CFSR reanalysis data,the southwest vortex from 1979 to 2020 is analyzed statistically.Then the environmental field of southwest vortex anomalies in summer(June-August)is studied by means of synthetic analysis.The basic characteristics of the interannual variation of the southwest vortex in recent 42 years and the environmental factors conducive to the formation of the southwest vortex in summer are obtained.The results showed that there were 3078 cases of southwest vortex in the past 42 years,with an average of 73.3 cases per year.More spring and summer,less autumn and winter.The frequency of occurrence increased in summer,and decreased in winter,and the change was not obvious in the other two seasons.The average lifetime of the southwest vortex is 15.9 h,and the average horizontal scale is 419.4 km.The duration and intensity of the southwest vortex increased over 42 years,while the horizontal scale decreased.When the upper upper-level jet stream is south to east and the South Asian high is weak,it is conducive to the formation of the southwest vortex in summer.The geopotential height distribution of"low in the north,high in the south"and"high in the east and low in the west"on the north and south sides of the middle and low-level Plateau and east of Lake Baikal and the East China Sea is conducive to the strengthening of southwest airflow on the east side of the plateau and the maintenance of west wind on the south side of the plateau.The uneven distribution of warm and cold advection and the unstable distribution of temperature field and humidity field"warm above and cold below,wet above and dry below"are also conducive to the formation of the southwest vortex.The 850 hPa water vapor transport channel between the Bay of Bengal and the South China Sea and the Sichuan Basin also creates favorable water vapor conditions for the formation of the southwest vortex.

关 键 词：西南涡 合成分析 年际变化 环流特征 

分 类 号：P445[天文地球—大气科学及气象学]