中国近50年寒潮冷空气的时空特征及其与北极海冰的关系

Spatial-Temporal Patterns of the Cold Surge Events in China in Recent 50 Years and Its Relationship with Arctic Sea Ice

利用中国具有较长时间序列的527个站点1961—2010年的日平均温度观测资料,美国国家环境预报中心和国家大气研究中心(NCEP/NCAR)再分析资料以及伊利莱诺斯大学的海冰密集度资料,分析了我国近50年来寒潮的时空变化及与其相联系的海冰和大气环流异常的关系。结果表明,中国寒潮冷空气活动频数存在两个主要模态,第一模态表现在中国北方冷空气活动频数呈年代际减少趋势,1980年之前寒潮冷空气频数偏多,1990年后寒潮冷空气频数偏少;第二模态表现为我国南方冷空气频数的年际振荡特征。第一模态寒潮冷空气频数的减少主要与全球变暖有关,北极海冰的减少使得1980年代后期北极涛动加强,并激发出欧亚遥相关波列进而影响我国的寒潮冷空气活动。第二模态则与近些年来夏季北极海冰的快速融化以及北极大气出现偶极子型环流异常有关,通过激发跨极型和类欧亚遥相关波列影响到后冬的中国南方寒潮冷空气活动增多。

Based on the observed daily mean temperature data from 527 China station with a long time se ries from the year 1961 to 2010, the National Center for Environmental Prediction/ National Center for Atmospheric Research （NCEP/NCAR） reanalysis dataset and the sea ice concentration （SIC） dataset from Illinois University, this study analysis the spatial temporal patterns of the cold surge events in China in re- cent 50 years and the related SIC anomaly and atmospheric circulation. It reveals that there are two leading modes of the cold surge frequency in China. The first mode shows obvious interdecadal variation of the cold surge frequency in north China, with higher than the normal frequency of cold surge occurrence before the year 1980, but lower after the year 1990. The second mode is mainly shown as interannual variability of the cold surge frequency in the south of China. The reduction of cold surge frequency in the first mode is mainly related to global warming. The reduction of the Arctic sea ice enhanced the Arctic Oscillation since the late of 1980 s and excited a wave trains of Eurasian teleconnection （EU） pattern and then influenced the cold surge events in China. The second mode is mainly related to the rapid melting of Arctic sea ice and the appearance of Arctic dipole anomaly of atmospheric circulation in the summer during the past few years, which increased the cold surge events in late winter in the south of China by exciting a EU- like wavetrain pattern.