A New Circulation Index to Describe Variations in Winter Temperature in Southwest China  

作　　者：申乐琳 陈隆勋 金啟华 朱艳峰 

机构地区：[1]National Climate Center, Laboratory for Climate Studies [2]Chinese Academy of Meteorological Sciences [3]National Meteorological Information Center

出　　处：《Journal of Meteorological Research》2015年第2期228-236,共9页气象学报（英文版）

基　　金：Supported by the National Natural Science Foundation of China(41375089)

摘　　要：A new circulation index（ISW） that can realistically describe winter temperature variations over Southwest China is defined based on analysis of the NCEP/NCAR reanalysis data（version 1） and the observations at585 stations in China. The study period is from January 1961 to February 2011. The relationship between ISW and general circulation patterns in East Asia is also analyzed. Results show that ISW successfully captures the variations in winter temperature over Southwest China. High ISW values correspond to the intensified Mongolian high, the weakened Aleutian low, increases in the strength of the Middle East westerly jet stream over the south of the Tibetan Plateau（TP）, and decreases in the strength of the subtropical westerly jet over the north of the TP. Meanwhile, the East Asian trough deepens and extends southwestward,making it easier for the cold air mass from the north to intrude Southwest China along the trough. These circulation patterns lead to a decrease in winter temperature over Southwest China（and vice versa）. In addition to the East Asian winter monsoon, the two westerly jets that dominate the upper level circulation over East Asia also exert important influences on winter temperature in Southwest China, especially the Middle East westerly jet to the south of the TP.A new circulation index（ISW） that can realistically describe winter temperature variations over Southwest China is defined based on analysis of the NCEP/NCAR reanalysis data（version 1） and the observations at585 stations in China. The study period is from January 1961 to February 2011. The relationship between ISW and general circulation patterns in East Asia is also analyzed. Results show that ISW successfully captures the variations in winter temperature over Southwest China. High ISW values correspond to the intensified Mongolian high, the weakened Aleutian low, increases in the strength of the Middle East westerly jet stream over the south of the Tibetan Plateau（TP）, and decreases in the strength of the subtropical westerly jet over the north of the TP. Meanwhile, the East Asian trough deepens and extends southwestward,making it easier for the cold air mass from the north to intrude Southwest China along the trough. These circulation patterns lead to a decrease in winter temperature over Southwest China（and vice versa）. In addition to the East Asian winter monsoon, the two westerly jets that dominate the upper level circulation over East Asia also exert important influences on winter temperature in Southwest China, especially the Middle East westerly jet to the south of the TP.

关 键 词：winter temperature Southwest China westerly jet Tibetan Plateau（TP） 

分 类 号：P423.3[天文地球—大气科学及气象学]