冬季北大西洋涛动和乌拉尔山阻塞环流对欧亚大陆变冷的协同影响  

Synergistic effects of winter North Atlantic Oscillation and Ural blocking circulation on Eurasian cooling

作　　者：陈亚楠 CHEN Yanan(Key Laboratory for Meteorological Disaster Prevention and Mitigation of Shandong,Jinan 250031,China;Shandong Institute of Meteorological Sciences,Jinan 250031,China)

机构地区：[1]山东省气象防灾减灾重点实验室,山东济南250031 [2]山东省气象科学研究所,山东济南250031

出　　处：《海洋气象学报》2023年第1期12-26,共15页Journal of Marine Meteorology

基　　金：山东省气象局科研项目(2021SDQN10)。

摘　　要：虽然全球平均表面气温不断升高,但在冬季欧亚大陆经常出现年际-年代际尺度上的变冷趋势。利用美国国家环境预报中心(National Centers for Environmental Prediction,NCEP)再分析资料,指出冬季影响欧亚大陆变冷的大气环流主要是北大西洋涛动(North Atlantic Oscillation,NAO)和乌拉尔山阻塞(Ural blocking,UB)的环流组合。其中,NAO环流可以在年际尺度上作为背景环流影响UB过程对欧亚低温天气的作用。统计分析发现,在NAO正(负)位相(NAO+/NAO-)环流背景下UB的发生频率可以解释冬季平均UB发生频率的52%(13%),表明NAO+环流有利于下游阻塞形势出现。尽管如此,研究发现在NAO-环流背景下的UB事件平均给欧亚地区带来的降温幅度更强,约是NAO+环流背景下的2倍,而且亚洲降温区的位置偏北约5°、偏东约13.5°。中等强度的NAO+环流背景下UB事件对欧亚降温的贡献更显著,强的NAO+环流背景下,UB过程在欧亚大陆中纬度地区产生的冷异常较弱,这与NAO+环流在欧亚大陆北部产生的明显增温有关。而在NAO-环流背景下,欧亚大陆北部有明显的降温,UB环流的出现会进一步将冷空气向南输送影响我国,这种情况主要反映的是NAO-环流异常对欧亚地区降温的作用,因此NAO-环流越强降温越强烈。Although the global mean surface temperature continues to rise,significant cooling trends at the interannual-decadal scale often occur over Eurasia in winter.Based on the NCEP(National Centers for Environmental Prediction)reanalysis data,it is suggested that the main atmospheric circulations affecting the cooling in the mid latitude of Eurasia in winter are the combination of North Atlantic Oscillation(NAO)and Ural blocking(UB)circulations.Among them,the NAO circulation can be used as a background circulation to influence the contribution of UB process to Eurasian cold anomaly at the interannual scale.Statistical analysis shows that the frequency of UB occurring simultaneously with a positive-phase(negative-phase)NAO(NAO+/NAO-)explains 52%(13%)of its average frequency in winter,which indicates that the NAO+circulation favors the downstream blocking occurrence.Nevertheless,the UB events related to a NAO-can cause a stronger Eurasian cold anomaly on average,which is about twice as strong as that of the UB events related to a NAO+,and the position of Asian cold anomaly is shifted by approximately 5°north and 13.5°east.It is also found that the UB event causes a significant cooling in Eurasia under the background of moderate NAO+circulation,and the cold anomaly generated by UB process in the mid latitude of Eurasia is relatively weak under the background of strong NAO+circulation,which is related to the obvious warming generated by NAO+circulation in the northern Eurasia.Under the background of NAO-circulation,there is an obvious cooling in the northern Eurasia before the UB,and the occurrence of UB circulation can transport cold air southward to affect China.It mainly reflects the effect of NAO-circulation on Eurasian cold anomaly,so the stronger the NAO-circulation,the stronger the cooling.

关 键 词：欧亚大陆变冷 大气环流 北大西洋涛动 乌拉尔山阻塞 

分 类 号：P461[天文地球—大气科学及气象学]