一个适用于描述中国大陆冬季气温变化的东亚冬季风指数  

An index of East Asian winter monsoon applied to description the Chinese mainland winter temperature changes.

作　　者：朱艳峰[1] 

机构地区：[1]国家气候中心,中国气象局气候研究开放实验室,北京100081

出　　处：《气象学报》2008年第5期781-788,共8页Acta Meteorologica Sinica

基　　金：国家气象局新技术项目(CMATG2005M04);国家自然科学基金(40505014)

摘　　要：利用1951年1月—2007年2月的NCEPV1格点资料和中国台站观测资料,定义了一个冬季风环流指数(IEAWM),并分析其与中国冬季气温和东亚大气环流变化的联系。结果表明该指数能够很好地反映东亚冬季风系统各成员的变化,兼顾北方和南方的环流状况和东西部热力差异的影响,改进了原有冬季风指数大多针对单一的冬季风环流成员及对中国冬季气温变化反映能力的不足,能够很好地反映中国冬季平均气温的异常变化。分析表明,当该指数为正值时东亚冬季风偏强,对应着地面西伯利亚高压和高空东亚大槽均偏强,东亚地区对流层中层的高-低纬度之间的纬向风经向切变加强,有利于中高纬度冷空气向南侵入,导致中国大陆地区气温偏低,反之亦然。IEAWM的年代际变化表明东亚冬季风在1985年之前偏强,1985年之后明显偏弱,这与1985年之后中国冬季变暖是一致的。Using the NCEP/NCAR reanalysis data （Version 1） and the observation data of China from January 1951 to February 2007, a new index of East Asian winter monsoon circulation （ IEAWM ） was defined based on comparison of previous different winter monsoon indices and circulation factors influencing the winter climate over china. Its relationships with winter temperature over China and large-scale circulation were analyzed. Results show that new index represents very well the winter temperature over China and the East Asia winter monsoon （EAWM） system. This index reflects the integrated effect of the circulations over high and low latitudes and the thermal difference between the continent and the ocean. While in the previous studies, most monsoon indices only describe the single monsoon member. The IEAWM is a good indicator of the intensity of the EAWM. Positive values of IEAWM correspond to strong EAWM, stronger than normal Siberian high and East Asian trough, and the strengthening of the meridional shear of 500 hPa zonal wind between high and low latitudes over East Asia, and therefore, the southward cold advection becomes strong and leads to the decrease in surface temperature over China; and vice versa. The obviously interdacal change is found in the IEAWM that it is positive before the mid-1980s, but negative since the mid-1980s, in good agree- ment with the fact of the winter warming in China after 1985.

关 键 词：东亚冬季风 环流指数 中国 冬季气温变化 

分 类 号：P462.41[天文地球—大气科学及气象学]