中国干旱半干旱地区的冷季快速增温

Enhanced Cold-Season Warming in Arid and Semi-Arid Regions of China

利用中国713个观测站均一化的月平均温度资料,详细分析了近55年中国温度变化的季节性及区域特征,并进一步分析了中国干旱半干旱区冷季增温前后的大气环流特征。年际变化结果表明,中国的增温现象主要是从20世纪80年代中期开始,90年代快速增长,21世纪初增温变缓,其中干旱半干旱区的年均增温速率是湿润半湿润区的1.7倍。季节性特征为冷季增温速率是暖季的1.9倍,干旱半干旱区的冷季增温速率较大,都超过了0.3℃·(10a)-1,其中青藏高原、内蒙古中部、东北和华北增温尤其显著,湿润半湿润区的冷季增温相对较慢,其中中西部地区比东部沿海增温较慢。干旱半干旱区的冷季温度在1986年左右发生显著暖突变,突变前后的大气环流对比分析表明,极涡强度减弱、东亚大槽和欧洲浅槽变浅、极地冷高压和西伯利亚高压偏弱、气旋性异常环流和东部地区的异常东南气流都有利于干旱半干旱区冷季的快速增温。

Using 55-year monthly homogenization surface air temperature at 713 stations from the National Climate Center of China,the seasonal and regional characteristics of warming in China have been investigated. In particular,the atmospheric circulation before and after cold-season warming over arid and semi-arid region have been analyzed. The interannual variation shows that warming began in the mid 1980 s,and increased fast in the1990 s,then gradually slowed down in the early 21 stcentury. The annual average warming trend in semi-arid and arid areas is 1. 7 times that in humid and semi-humid areas. As for seasonal characteristics,the warming trend during cold-season is 1. 9 times that of warm-season. The warming trend is comparatively fast in arid and semiarid areas with more than 0. 3℃ ·( 10a)- 1and particularly notable over the Qinghai-Xizang Plateau,middle inner Mongolia,northeast and north China. However,the warming trend in humid and semi-humid areas is relatively slow,in which the central and west regions is slower than east coast. The cold season temperature in arid and semi-arid areas experienced a significantly abrupt change from cold to warm in 1986. A composite analysis is used here to investigate the response of the atmospheric circulation. The weakening of arctic polar vortex,eastern Asia trough,shallow trough in Europe and Siberian High,and anomaly cyclonic circulation as well as abnormal southeast wind in eastern China all could induce the warming in semi-arid and arid areas.