Northern Hemisphere Stratospheric Polar Vortex Extremes in February under the Control of Downward Wave Flux in the Lower Stratosphere  

作　　者：WEI Ke CHEN Wen 

机构地区：[1]Center for Monsoon System Research,Institute of Atmospheric Physics,Chinese Academy of Sciences,Beijing 100190,China

出　　处：《Atmospheric and Oceanic Science Letters》2012年第3期183-188,共6页大气和海洋科学快报（英文版）

基　　金：supported by the National Basic Research Program of China (973Program) (Grant No. 2010CB428603);the National Natural Science Foundation of China (Grant Nos. 40805017 and 41175041)

摘　　要：Using ECWMF ERA-40 and Interim reanalysis data, the planetary wave fluxes associated with the February extreme stratospheric polar vortex were studied. Using the three-dimensional Eliassen-Palm (EP) flux as a measure of the wave activity propagation, the authors show that the unusual warm years in the Arctic feature an anomalous weak stratosphere-troposphere coupling and weak downward wave flux at the lower stratosphere, especially over the North America and North Atlantic (NANA) region. The extremely cold years are characterized by strong stratosphere-troposphere coupling and strong downward wave flux in this region. The refractive index is used to examine the conception of planetary wave reflection, which shows a large refractive index (low reflection) for the extremely warm years and a small refractive index (high reflection) for the extremely cold years. This study reveals the importance of the downward planetary wave propagation from the stratosphere to the troposphere for explaining the unusual state of the stratospheric polar vortex in February.Using ECWMF ERA-40 and Interim reanalysis data, the planetary wave fluxes associated with the February extreme stratospheric polar vortex were studied. Using the three-dimensional Eliassen-Palm （EP） flux as a measure of the wave activity propagation, the authors show that the unusual warm years in the Arctic feature an anomalous weak stratosphere-troposphere coupling and weak downward wave flux at the lower stratosphere, especially over the North America and North Atlantic （NANA） region. The extremely cold years are characterized by strong stratosphere-troposphere coupling and strong downward wave flux in this region. The refractive index is used to examine the conception of planetary wave reflection, which shows a large refractive index （low reflection） for the extremely warm years and a small refractive index （high reflection） for the extremely cold years. This study reveals the importance of the downward planetary wave propagation from the stratosphere to the troposphere for explaining the unusual state of the stratospheric polar vortex in February.

关 键 词：stratospheric sudden warming atmospheric dynamics middle atmosphere planetary wave reflection 

分 类 号：P42[天文地球—大气科学及气象学] TQ028.8[化学工程]