低平流层准两年变率研究

分析NCAR/NCEP40年再分析资料得出,赤道低平流层纬向风年际变率的平均周期约28.2个月,最大振幅在20hPa,西(东)风距平垂直下传平均速度1.21(1.04)km/月。用10hPa和70hPa月平均纬向风标准化距平之差可反映整层准两年变率的相位,低平流层两半球中纬气温有与之配合的振荡,西(东)风切变时,中纬气温偏低(高)。赤道纬向风准两年变率引起的经圈环流异常是联系低纬纬向风与中纬气温准两年变率的纽带。

Study on quasi-biennial variability in lower stratosphere

Based on the analyses of NCAR/NCEP 40 years reanalysis data set,it is found that the mean period of interannual variability of zonal wind in the equatorial lower stratosphere is 28.2 months,the maximum amplitudes appear at 20hPa.The mean rate at which the westerly(easterly) wind anomalies progresses downward is about 1.21(1.04)km/month.The difference between standard deviations of monthly mean zonal winds at 10 and 70hPa can indicate the phases of the quasi biennial variability in the whole lower stratosphere.Temperature anomalies in middle latitudes of both hemispheres oscillate in coordination with the QBO of zonal wind in equatorial low stratosphere.The valleys(peaks) of the temperature anomalies in middle latitudes appear when vertical shear of zonal wind in equatorial lower stratosphere is westerly(easterly).The meridional circulation anomalies induced by the quasi biennial variability of equatorial zonal wind are the link between them.