西北东部夏季极端干旱事件机理分析
投稿时间: 2014-01-06  最后修改时间: 2014-01-06  点此下载全文
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作者单位E-mail
朱伟军 南京信息工程大学 weijun@nuist.edu.cn 
王燕娜 南京信息工程大学  
周兵 国家气候中心 bingz@cma.gov.cn 
潘佳 南京信息工程大学  
基金项目:国家自然科学基金资助项目(41075070)、公益性行业(气象)科研专项(GYHY201306028)和江苏高校优势学科建设工程(PAPD)共同资助
中文摘要:利用国家气候中心提供的1951-2012年逐日降水、温度和综合气象干旱指数资料、逐月NCEP/NCAR再分析资料,NOAA气候预测中心海温资料等。采用REOF分析、动力诊断、相关分析以及合成分析等方法,从大气环流异常特征、高空急流与季风异常等方面揭示西北东部夏季极端干旱事件的可能机理。研究发现西北东部夏季极端干旱发生时,副热带急流轴“倾斜”,其强度与东亚夏季风均偏弱的事实。西北东部夏季出现极端干旱现象的主要原因是:由于急流轴的倾斜,导致西北东部地区高层大范围的异常辐合;同时,季风强度偏弱,该地区处于水汽源区;高低层的配置及大尺度环流形势不利于降水的产生。
中文关键词:西北东部  夏季  极端干旱  环流异常  成因分析
 
Study on Mechanism of the Extreme Drought Events over Eastern of Northwest China in Summer
Abstract:Based on the 1951-2012 daily precipitation and temperature data and daily Compound Index (CI) provided by National Climate Centre, the monthly NCEP/NCAR reanalysis data and the NOAA Climate Prediction Centre extended reconstructed SST data, The characteristics of atmospheric circulation anomalies and abnormal of East Asian monsoon and tropospheric jet stream were researched, and the mechanism of the extreme drought events over Eastern of Northwest China in summer was revealed by using REOF method, correlation analysis, composite analysis and dynamical diagnosis. It was found that the tropospheric jet’s axis behavior northwest–southeast tilt and its strength weekend as well as the weakest Asian monsoon when extreme drought events occurred in summer. The main causes for the extreme drought events in summer were as follows: Responses to the tropospheric jet’s axis tilt, a wide range of convergence exist in the tropospheric level of Eastern of Northwest China; at the same time, East Asian monsoon appearance to weakest and there were negative anomaly water vapor fluxes; the abnormal atmospheric circulation was unfavorable for precipitation.
keywords:Eastern of Northwest China  summer  extreme dry events  atmospheric circulation anomalies  mechanism
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