极区夏季中间层半日潮汐的VHF雷达观测

采用德国SOUSYVHF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1/12c

VHF RADAR OBSERVATION OF THE SEMIDIURNAL TIDE IN THE SUMMER POLAR MESOSPHERE

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.