Short-term variability of tides and mean wind in the summer polar mesosphere

YI Fan,LIU Ren qiang (Department of Radio Science and Technology, Wuhan University, Wuhan Hubei 430072, China)  

Data obtained from the mobile SOUSY VHF radar at and φya /Norway (69°N,16°E) during the MAC/SINE campaign in summer l987 have been used to study the variability of tides and mean wind in the polar mesosphere. It is shown that the spectral peak corresponding to the semidiurnal tide dominates and persists almost uninterruptedly in time. The spectral peak corresponding to the diurnal tide is usually secondary and interrupted in time. Occasionally it enhances to an intensity comparable to that of the semidiurnal tide. The terdiurnal tide rarely presents a prominent spectral peak. The frequency corresponding to each tidal component often shows a deviation from its definition value. This likely represents a temporary or disturbed state. The time variations in either of the zonal and meridional mean winds for two heights with 2.7km distance show a considerable similarity, but their respective variation trends are different, indicating an anisotropy in the variability of the horizontal mean wind. Since the frequency values of each tidal component in the zonal and meridional winds are different, the hodograph of its wind vector with respect to time is no longer a close ellipse, but still has a clockwise rotation.

【Fund】： 国家杰出青年科学基金!4 96 2 5 40 7);; 国家基金委“九五”重大项目!(4 9990 45 0 )
【CateGory Index】： P434

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