Extreme Cold Events in North America and Eurasia in November-December 2022: A Potential Vorticity Gradient Perspective  

作　　者：Yao YAO Wenqin ZHUO Zhaohui GONG Binhe LUO Dehai LUO Fei ZHENG Linhao ZHONG Fei HUANG Shuangmei MA Congwen ZHU Tianjun ZHOU 

机构地区：[1]CAS Key Laboratory of Regional Climate-Environment for Temperate East Asia,Institute of Atmospheric Physics,Chinese Academy of Sciences,Beijing 100029,China [2]University of Chinese Academy of Sciences,Beijing 100049,China [3]Frontier Science Center for Deep Ocean Multispheres and Earth System(FDOMES)and Physical Oceanography Laboratory,Ocean University of China,Qingdao 266100,China [4]State Key Laboratory of Earth Surface Processes and Resource Ecology,Beijing Normal University,Beijing 100875,China [5]International Center for Climate and Environment Science(ICCES),Institute of Atmospheric Physics,Chinese Academy of Sciences,Beijing 100029,China [6]National Institute of Natural Hazards,Ministry of Emergency Management of China,Beijing 100085,China [7]State Key Laboratory of Severe Weather,Chinese Academy of Meteorological Sciences,China Meteorological Administration,Beijing 100081,China [8]State Key Laboratory of Numerical Modelling for Atmospheric Sciences and Geophysical Fluid Dynamics(LASG),Institute of Atmospheric Physics,Chinese Academy of Sciences,Beijing 100029,China

出　　处：《Advances in Atmospheric Sciences》2023年第6期953-962,I0002-I0005,共14页大气科学进展（英文版）

基　　金：support from the National Natural Science Foundation of China (Grant Nos. 41975068, 42150204, 42288101, 42075024, and 41830969)。

摘　　要：From 17 November to 27 December 2022, extremely cold snowstorms frequently swept across North America and Eurasia. Diagnostic analysis reveals that these extreme cold events were closely related to the establishment of blocking circulations. Alaska Blocking(AB) and subsequent Ural Blocking(UB) episodes are linked to the phase transition of the North Atlantic Oscillation(NAO) and represent the main atmospheric regimes in the Northern Hemisphere. The downstream dispersion and propagation of Rossby wave packets from Alaska to East Asia provide a large-scale connection between AB and UB episodes. Based on the nonlinear multi-scale interaction(NMI) model, we found that the meridional potential vorticity gradient(PVy) in November and December of 2022 was anomalously weak in the mid-high latitudes from North America to Eurasia and provided a favorable background for the prolonged maintenance of UB and AB events and the generation of associated severe extreme snowstorms. However, the difference in the UB in terms of its persistence,location, and strength between November and December is related to the positive(negative) NAO in November(December). During the La Ni?a winter of 2022, the UB and AB events are related to the downward propagation of stratospheric anomalies, in addition to contributions by La Ni?a and low Arctic sea ice concentrations as they pertain to reducing PVyin mid-latitudes.

关 键 词：successive cold extremes atmospheric blocking NAO potential vorticity gradient water vapor backward tracking Arctic sea ice La Niña 

分 类 号：P458.3[天文地球—大气科学及气象学] P732