Interannual Variations of the Blocking High over the Ural Mountains and Its Association with the AO/NAO in Boreal Winter  

作　　者：李超 张庆云 纪立人 彭京备 

机构地区：[1]International Center for Climate and Environment Sciences,Institute of Atmospheric Physics,Chinese Academy of Sciences [2]Graduate University of the Chinese Academy of Sciences [3]State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics,Institute of Atmospheric Physics,Chinese Academy of Sciences

出　　处：《Acta meteorologica Sinica》2012年第2期163-175,共13页

基　　金：Supported by the China Meteorological Administration Special Public Welfare Research Fund (GYHY201106015);National Science and Technology Support Program of China (2009BAC51B02);National Basic Research and Development (973) Program of China (2009CB421401);National Natural Science Foundation of China (40975022)

摘　　要：This paper analyzes interannual variations of the blocking high over the Ural Mountains in the boreal winter and their association with the Arctic Oscillation/North Atlantic Oscillation（AO/NAO）.In January,the relationship between the Ural blocking high（UR） and the AO index is statistically significant.The UR tends to occur more frequently and with greater strength during negative AO periods.Some strong URs also occur during positive AO phases（positive UR-AO events）,as in January 2008.This paper discusses the characteristics of atmospheric circulation in the cases of positive UR-AO events and contrast cases（negative UR-AO events）.The eastward extending of the Icelandic Low（IL） center and the associated NAO dipole anomaly pattern in the upstream region may play a more important role for the UR-AO events.When the center of the IL shifts eastward to 30 W,the amplitude of zonal wavenumber 2（wavenumber 3） is intensified in the positive（negative） UR-AO events,which favors positive（negative） height anomalies over the Urals.Further analyses indicate that the intensified zonal wind in high latitudes and weakened zonal wind in midlatitudes over the North Atlantic Ocean render the eastward shift of the IL and the NAO dipole anomaly pattern.The Ural blocking in January 2008 bears similar characteristics to the positive UR-AO events.This paper analyzes interannual variations of the blocking high over the Ural Mountains in the boreal winter and their association with the Arctic Oscillation/North Atlantic Oscillation（AO/NAO）.In January,the relationship between the Ural blocking high（UR） and the AO index is statistically significant.The UR tends to occur more frequently and with greater strength during negative AO periods.Some strong URs also occur during positive AO phases（positive UR-AO events）,as in January 2008.This paper discusses the characteristics of atmospheric circulation in the cases of positive UR-AO events and contrast cases（negative UR-AO events）.The eastward extending of the Icelandic Low（IL） center and the associated NAO dipole anomaly pattern in the upstream region may play a more important role for the UR-AO events.When the center of the IL shifts eastward to 30 W,the amplitude of zonal wavenumber 2（wavenumber 3） is intensified in the positive（negative） UR-AO events,which favors positive（negative） height anomalies over the Urals.Further analyses indicate that the intensified zonal wind in high latitudes and weakened zonal wind in midlatitudes over the North Atlantic Ocean render the eastward shift of the IL and the NAO dipole anomaly pattern.The Ural blocking in January 2008 bears similar characteristics to the positive UR-AO events.

关 键 词：Ural blocking high AO NAO dipole anomaly pattern Icelandic Low 

分 类 号：P467[天文地球—大气科学及气象学]