极区夏季中间层半日潮汐的VHF雷达观测

摘要

Data obtained from the mobile SOUSY VHF radar at And/Norway(69, 16) during the MAC/SINE campaign in summer 1987have been used to study the structure characteristics and variability ofthe semidiurnal tide in the polar mesosphere. It is shown that thespectral peak corresponding to the semidiurnal tide dominates andpersists almost uninterruptedly in time. The corresponding frequencyoften deviates from 1/12 c{-1. This likely represents atemporary or disturbed state. The amplitude of the stable semidiurnaltide increases rapidly with height and shows a saturation behavior atthe height of about 87.9 km. The phase front of the tide movesdownward, indicating the associated energy flux transports upward. Thephase of the meridional component often leads that of the zonalcomponent about /4-/2 (equivalent to 1.5-3 h), resultingin a clockwise hodograph of the wind vector with respect to time. Thevalues of wave-associated parameters are obtained by a harmonic analysisin which the variable frequency corresponding to spectral peak istraced. By and large, the time variation trends of the tide in the zonaland meridional components are similar, but display an anisotropy to someextent.%采用德国SOUSY VHF雷达观测数据,研究了极区夏季中间层半日潮汐的结构和变化特征.纬向和经向风的动态Lomb-Scargle谱表明,半日潮是中间层高度上占支配地位的波动,其谱峰对应的频率一般与1/12 c-1有偏离,说明它们经常处在被扰动状态.稳定的半日潮振幅随高度增加而迅速增长,在87.9 km高度附近达到饱和;经向分量的相位一般比纬向分量的相位超前/4-/2,从而水平扰动速度矢量端点随时间变化的轨迹显示出顺时针方向旋转的特征.半日潮汐特征参量在纬向和经向风中随时间的变化在基本趋势一致的基础上显示出一定程度的各向异性.