2003—2004年冬季北半球平流层极涡在等熵位涡坐标下的动力分析  

A dynamical diagnosis of the stratospheric polar vortex in 2003—2004 northern winters viewed in an isentropic potential vorticity coordinate.

作　　者：刘毅[1] 陆春晖[1,2] 管兆勇[2] 任荣彩[3] 

机构地区：[1]中国科学院大气物理研究所中层大气与全球环境探测重点实验室,北京100029 [2]南京信息工程大学大气科学学院,南京210044 [3]中国科学院大气物理研究所大气科学和地球流体力学数值模拟国家重点实验室,北京100029

出　　处：《气象学报》2010年第3期376-386,共11页Acta Meteorologica Sinica

基　　金：国家自然科学基金重点项目(40633015)

摘　　要：利用欧洲中尺度天气预报中心(ECMWF)逐日的60层模式资料构建了半拉格朗日的二维θ-PVLAT坐标,在新坐标中对2003—2004年冬季北半球平流层极涡的活动过程进行诊断分析。通过对位涡距平场在新坐标下的EOF分析得到极涡扰动指数,由该指数出发对风场、温度场进行超前/滞后回归分析,得到极涡活动过程中平、对流层大气的环流输送特征。结果表明:(1)θ-PVLAT坐标有很好的物质性,它能够较好地反映出空气物质的输送特征,尤其在北半球冬季的高纬度地区它能更加真实的表达出大气环流风场、温度场的变化;(2)在极涡活动过程中平流层里存在着一对向极、向下的传播模态,不同符号的纬向风和温度异常的信号沿着这两个模态传播,而对流层中也有一向赤道的传播模态;(3)平流层中向极、向下的传播模态和对流层中向赤道的传播模态在时间上存在着一定的联系,当纬向风异常在高层传播到达极区时,低层开始向赤道传播;(4)整个极涡活动过程可以用一个非绝热加热作用和斜压波动作用共同驱动的经圈质量环流解释,这一环流造成了中低纬度地区的暖空气和极地区域的冷空气在平流层-对流层之间交换,对整层大气的热力、动力结构进行了重新组合。In this paper the Northern Hemisphere stratospheric polar vortex oscillation in a new semi-Lagrangianθ-PVLAT coordinate constructed using the daily ECMWF 60-level data during 2003-2004 winters is diagnosed.From the EOF analysis of the potential vorticity anomalies in this new coordinate,we get the polar vortex oscillation（PVO） index on which the lead/lag regression analyses of the zonal wind and temperature are completed with the characteristics of stratospheric and tropospheric circulations during PVO progress obtained.The main results show that（1） Theθ-PVLAT coordinate has nice materiality and does well in describing the variation of mass transport,particularly the variation of atmospheric circulation in the North Hemispheric high latitudes;（2） there are a pair of propagating modes that are pole-ward and down-ward in the stratosphere along which the zonal wind and temperature anomalies with opposite signs propagate and an equator-ward propagating mode in the troposphere;（3） there exists a certain temporal relation between these two propagating modes：the starting time of the equator -ward propagating in the lower atmosphere is nearly the same as the arrival time in the polar zone of the pole-ward and downward propagating in the stratosphere;（4） we can explain the variance of polar vortex by a meridional mass circulation driven by both the diabatic heating and baroclinic waves.This mass circulation leads to the exchange between warm air in the low latitude areas and cold air in the polar areas by the process of Stratospheric and Tropospheric Exchange（STE）,and thus reconstructs the dynamical and thermal patterns of the whole atmosphere.

关 键 词：θ-PVLAT坐标 经验正交分解 超前/滞后回归分析 质量环流 

分 类 号：P458.121[天文地球—大气科学及气象学]