Observational Zonal Mean Flow Anomalies:Vacillation or Poleward Propagation?  

作　　者：SONG Jie 

机构地区：[1]The State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics,Institute of Atmospheric Physics,Chinese Academy of Sciences

出　　处：《Atmospheric and Oceanic Science Letters》2013年第1期1-7,共7页大气和海洋科学快报（英文版）

基　　金：sponsored by the National Key Technologies R&D Program of China (Grant No. 2009BAC51B02);the National Basic Research Program of China (973 Program,Grant No. 2010CB950401);the National Nature Science Foundation of China (Grant Nos. U0833602 and 40805023);the State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics Free Exploration Fund

摘　　要：North-south displacements and meridional vacillations of the eddy-driven jet are widely accepted as the dominant cause of variability of the observational zonal-mean zonal wind anomalies(denoted [u]').In this study,a new idea regarding the primary variability of the observational [u]' in the middle latitude troposphere is presented.It is hypothesized that there are two different classes of primary variability of the observational [u]':the poleward propagation of the [u]'(abbreviated as PP) and meridional vacillations.To validate this hypothesis,one-point correlation maps of [u]' at 200-hPa during the boreal cold season(November-April) of every year from 1957-2002 are used as a criterion.Twelve PP years,in which the PP events are dominant in the variability of [u]',and 15 no_PP years,in which the PP events are recessive and the meridional vacillations are dominant in the variability of [u]',are examined.The results show that the variabilities of [u]' are different in the chosen PP and no_PP years.In the PP years,the PP events dominate the variability of [u]';however,the meridional vacillations are prevalent in the no_PP years.North-south displacements and meridional vacillations of the eddy-driven jet are widely accepted as the dominant cause of variability of the observational zonal-mean zonal wind anomalies （denoted [u]＇）. In this study, a new idea regarding the primary variability of the observational [u]＇ in the middle latitude troposphere is presented. It is hypothesized that there are two different classes of primary variability of the observational [u]＇： the poleward propagation of the [u]＇ （abbreviated as PP） and meridional vacillations. To validate this hypothesis, one-point correlation maps of [u]＇ at 200-hPa during the boreal cold season （November-April） of every year from 1957-2002 are used as a criterion. Twelve PP years, in which the PP events are dominant in the variability of [u]＇, and 15 no_PP years, in which the PP events are recessive and the meridional vacillations are dominant in the vari- ability of [u]＇, are examined. The results show that the variabilities of [u]＇ are different in the chosen PP and no_PP years. In the PP years, the PP events dominate the variability of [u]＇; however, the meridional vacillations are prevalent in the no_PP years.

关 键 词：zonal-mean zonal wind zonal index pole- ward propagation 

分 类 号：P412.1[天文地球—大气科学及气象学]