东北春季极端低温的变化特征及其与大西洋海温的关系

摘要

利用1958—2007年全球海温、位势高度场月平均资料和我国东北地区64个测站的春季地面气温资料,分析了我国东北地区春季极端低温的时空变化特征及其与大气环流和海温异常的关系。结果表明：近50a来,我国东北春季极端低温事件频数整体呈减少趋势;极端低温频数主要存在全区一致变化型和南北反相变化型两种模态;极端低温事件频数与北极涛动存在显著负相关关系,同时在极端低温多年,极涡较弱,乌拉尔山阻塞高压偏强,东北冷涡较强,反之亦然;影响我国东北地区春季极端低温的关键海区为中北大西洋海区,极端低温多年,中北大西洋海温较常年偏冷,反之则中北大西洋海温较常年偏暖。这对于预测东北春季极端低温事件的年际变化具有很好的指示意义。数值试验结果表明,中北大西洋海温异常可激发欧亚波列,致使中国东北温度异常。%By using the mean monthly dataset of global sea surface temperature and geopotential height fields,and the surface air temperature records of 64 stations in spring in Northeast China from 1958 and 2007,this paper analyzes the spatial/temporal variation characteristics of spring extreme low temperature（SELT） in Northeast China,and its relationship with atmospheric circulation and sea surface temperature（SST） anomalies.The results show that：The occurrence frequency of SELT in Northeastern China has tended to decrease;The frequency has two major modes：consistent change of the whole area and reversed-phase change of the North-South;There is a significant negative correlation between the frequency of SELT and the AO index.For years with more extreme low temperature events,the polar vortex is weak,with strong Ural blocking high and cold vortex over Northeast China,and vice versa.Result also indicates that the key SST area affecting the SELT locates in the north-middle Atlantic Ocean,with negative（positive） SST anomalies for years with more（less） SELT events,implying important significance for SELT prediction.In addition,numerical simulations also show that SST anomalies in the north-middle Atlantic Ocean can cause air temperature anomalies over Northeast China by exciting Eurasian wave trains.