2021年5月江西降水异常偏多特征及成因分析  

Study on the Characteristics and Causes of Precipitation Anomaly in Jiangxi in May of 2021

作　　者：谢佳杏 董保华 郭泓 张勇平 罗少华[1] Xie Jiaxing;Dong Baohua;Guo Hong;Zhang Yongping;Luo Shaohua(Jiangxi Climate Center,Nanchang 330046,China;Jiangxi Meteorological Service Center,Nanchang 330029,China;Xinyu Meteorological Bureau,Xinyu 338001,China)

机构地区：[1]江西省气候中心,江西南昌330096 [2]江西省气象服务中心,江西南昌330096 [3]新余市气象局,江西新余338001

出　　处：《气象与减灾研究》2024年第1期34-41,共8页Meteorology and Disaster Reduction Research

基　　金：江西省气象局面上项目(编号:JX2022Q03);江西省气象局重点项目“多种降水情景下的山洪演进模拟试验”.

摘　　要：2021年5月江西省降水异常偏多,多项降水指数突破历史极值,异常的降水在累计降水量、降水强度、日降水量等方面表现出极端性。利用1961—2021年江西省83站逐日降水资料和NCEP/NCAR再分析资料,分析了2021年5月江西降水异常偏多的主要原因。结果表明:5月大气环流异常是造成江西降水偏多的直接原因,欧亚中高纬500 hPa层环流呈“两脊一槽”的分布特征,受北大西洋三极子正位相影响,中国东北及周围地区位势高度为负距平,东北冷涡异常活跃,中高纬环流经向度增加,冷空气不断南下为降水提供了环流条件。西太平洋副热带高压月内加强西伸,为降水提供充足的水汽条件。此外,南海夏季风爆发偏晚和5月在印度洋活跃的热带季节内振荡对5月江西降水偏多有一定的指示意义。In May of 2021,the precipitation was more than normal in Jiangxi,with multiple precipitation indices hit the highest re-cord for the same period in history.The abnormal precipitation presented significant extremes in terms of cumulative rainfall,rainfall intensity and daily rainfall.Based on the precipitation data of 83 meteorological observation stations in Jiangxi during 1961-2021 and the NCEP/NCAR reanalysis data,the major causes of precipitation anomalies in May 2021 were analyzed.The results showed that the abnormal atmospheric circulation was the direct cause responsible for heavy rainfall.The atmospheric circulation at 500 hPa over mid-dle and high latitudes of Eurasia presented an anomalous pattern of“two ridges and one trough”.Affected by the positive phase of the North Atlantic Triode,the geopotential height of Northeast China and its surrounding areas was negative anomaly,leading to the anom-alous activity of the Northeast China cold vortex,the obviously increased meridional characteristics of the mid-high latitude circula-tion,and southward movement of cold air,providing circulation conditions for the rainfall.The Western Pacific Subtropical High was stronger and the position was westward,providing adequate moisture to the rainfall.Moreover,the late onset of the South China Sea summer monsoon and Madden-Julian Oscillation activities over the Indian Ocean in May had certain implications for the excessive ab-normal precipitation in Jiangxi.

关 键 词：降水异常 大气环流 南海夏季风 季节内振荡 

分 类 号：P461[天文地球—大气科学及气象学]