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江西省2015年11月降水异常特征及其成因

阙志萍1,吴  凡1周军辉2   

  1. 1.江西省气象服务中心,江西南昌330029;
    2.江西省气象局应急与减灾处,江西南昌330029
  • 出版日期:2018-04-30 发布日期:2018-04-30
  • 作者简介:阙志萍(1987— ),女,江西抚州人,硕士,工程师,主要从事季风与季节内振荡及短期气候预测研究. E-mail:quezhiping@sina.com。
  • 基金资助:

    国家自然基金重点国际(地区)合作研究项目(41520104008)资助

Rainfall Anomaly and Its Causes in Jiangxi Province in November 2015

QUE Zhiping1, WU Fan1, ZHOU Junhui2   

  1. 1. Meteorological Service Center of Jiangxi Province, Nanchang 330029, China;
    2. Department of Emergency and Disaster Reduction of Jiangxi Provincial Meteorological Bureau, Nanchang 330029, China
  • Online:2018-04-30 Published:2018-04-30

摘要:

利用江西92个地面台站逐日降水资料,结合NCEP/NCAR逐日再分析资料、NOAA逐月海温资料及国家气候中心整编的74项环流指数和Nio3指数等资料,分析江西2015年11月降水异常特征及大尺度环流特征,并探讨2014年9月开始的超强厄尔尼诺事件对江西降水和大气环流的影响。结果表明:(1)2015年11月江西降水较常年同期偏多1.8倍,主要集中在上旬末和中旬,降水偏多较明显的地区主要位于赣中南部和赣南北部;(2)2015年11月中旬江西强降水期间,北半球环流形势异常明显,亚欧中高纬范围为明显的 “1槽1脊”形势,西太平洋副热带高压偏强、偏西,东亚冬季风偏弱,有利于大量暖湿气流向北输送,并与南下冷空气在江南上空交汇,从而使江西出现强降水;(3)2015年11月江西强降水与海温呈明显正相关,Nio3区海温越高,则越有利于江西中北部降水增多,而热带印度洋海温对江西降水的影响主要集中在浙赣铁路沿线到赣州北部,而赣州南部的降水受海温影响较小;(4)受超强厄尔尼诺事件影响,Walker环流减弱,叠加热带印度洋海温偏暖的影响,副高偏西、偏强;同时Hadley环流减弱,使得江南地区上升运动加强,东亚冬季风偏弱,从而导致江西降水偏多。

关键词: 异常降水, 大气环流, 厄尔尼诺, 海温

Abstract:

Based on the daily precipitation data of 92 weather stations in Jiangxi Province, daily reanalysis data of NCEP/NCAR, monthly sea surface temperature (SST) of NOAA and circulation indexes data and Niño3 indices from National Climate Center of China during 1961-2015, the characteristics of rainfall anomalies in Jiangxi and large-scale atmospheric circulation in November 2015 were analyzed, and the effects of super strong El Niño since September 2014 on rainfall in Jiangxi Province and atmospheric circulation in November 2015 were discussed. The results are as follows: (1) The precipitation in November 2015 in Jiangxi Province was 1.8 times more than the normal, and it mainly concentrated from the end of early and middle ten-day of November in the south area of middle Jiangxi and the north area of southern Jiangxi. (2) The anomalies of atmospheric circulation over the Northern Hemisphere was obvious during the severe rainfall process in mid-November 2015, the 500 hPa geopotential height field appeared an obvious pattern with ‘one ridge and one trough’ over the middle and high latitudes of Eurasia, and the western Pacific subtropical high was stronger and its position was westward and East Asian winter monsoon was weaker, which was beneficial to transferring of warm and moist airflow to northward. The cold and warm airflow met over the south of the Yangtze River, which caused the heavy rainfall in Jiangxi Province. (3) The precipitation in November 2015 in Jiangxi was positively correlated with SST. The higher SST in Niño3 area was conductive to the more rainfall in the middle and north of Jiangxi Province, while the influence of SST in the tropical Indian Ocean on rainfall was mainly concentrated in the areas along Zhejiang-Jiangxi railway and the north of Ganzhou. However, SST had a little effect on the precipitation in the south of Ganzhou. (4) Combined with the abnormally warmer SST in the tropical Indian Ocean, the Walker circulation weakened due to the effect of the super strong El Niño, which caused the enhancement and the location to westward of the western Pacific subtropical high. Meanwhile, the Hadley circulation weakened, which led to stronger ascending motion over the south of the Yangtze River and weaker the East Asian winter monsoon, and further caused the more precipitation in Jiangxi.

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