ENSO对中国冬季天气尺度气温变率的影响及可能机理

基于1960—2017年中国国家气象信息中心整编的753站逐日平均温度资料、美国国家海洋大气中心（NOAA）重建的逐月海表温度资料以及美国国家环境预测中心/国家大气研究中心（NCEP/NCAR）提供的再分析大气环流资料，分析了ENSO对中国冬季天气尺度气温变率的影响。结果表明，ENSO与中国东部大部分地区的冬季天气尺度气温变率呈显著正相关，即厄尔尼诺年冬季，中国气温波动幅度增大，天气尺度气温变率明显较强；而拉尼娜年冬季，气温变化相对平稳，天气尺度温度变率较小。进一步研究发现，厄尔尼诺事件加强了冬季欧亚大陆中高纬度地区的经向温度梯度，根据热成风原理，局地大气斜压性增强，西伯利亚地区的风暴活动和下游东亚地区大气环流的天气尺度变异也随之加强，因而有利于中国大部分地区天气尺度温度变率的增大。拉尼娜年冬季，异常情况与之大致相反。 

ENSO impact on the variability of wintertime synoptic-scale air temperature over China and possible mechanisms behind

The present study investigates ENSO impact on the variability of wintertime synoptic-scale air temperature over China based on daily averaged air temperature data collected at 753 stations and compiled by the National Meteorological Information Center, the NOAA reconstructed monthly sea surface temperature and the NCEP/NCAR reanalysis data from 1960 to 2017. The results show that ENSO is significantly positively correlated with wintertime synoptic-scale air temperature variability in a large area of eastern China. The fluctuation of temperature and synoptic-scale air temperature variability are usually stronger than normal during El Niño winters. In contrast, the synoptic-scale air temperature variability is weakened during La Niña winters. Further research finds that during El Niño winters, the meridional temperature gradient in the middle and high latitudes of Eurasia strengthens, leading to enhanced local atmospheric baroclinicity according to the thermal wind relationship and thus further increasing storm activities in the Siberian region and synoptic-scale variation of atmospheric circulation in East Asia region. Correspondingly, the synoptic-scale air temperature variability enhances in most areas of China. Roughly opposite mechanisms apply during La Niña winters.