Satellite observations of thermospheric tides: Results from the Wind Imaging Interferometer on UARS
Satellite observations of thermospheric tides: Results from the Wind Imaging Interferometer on UARS
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DOI：
10.1029/95jd03359
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发表时间：
1996-02
影响因子：
--
通讯作者：
C. McLandress;G. Shepherd;B. Solheim
中科院分区：
文献类型：
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作者：
C. McLandress;G. Shepherd;B. Solheim
对高层大气研究卫星上的风成像干涉仪（WINDII）测量的热层风进行了分析，以了解太阳潮汐的迁移。这些数据涵盖从 1992 年 2 月开始的 2 年时间，是从原子氧 O(1S) 557.7 nm 发射中获得的，它提供了白天 90 至 200 公里高度范围和夜间 90 至 110 公里范围的观测。副热带低层热层以昼夜传播潮汐为主，潮汐的垂直波长约为 22 公里，振幅增长至 95 公里，并在分子扩散大大减少垂直切变的上方迅速衰减。尽管相位全年保持相当均匀，但日潮幅有明显的半年振荡。在 20°N 和 20°S 处，经向风和纬向风分量在春分点达到最大值，分别约为 70 和 40 m/s，而至日最小值几乎小了 2 倍。在35°N处，日潮半年振幅振荡在低层热层中仍然存在，但在100公里以上则被年周期所取代，最大出现在7月和8月。这与 35°S 形成鲜明对比，那里没有 7/8 月峰值，半年振荡延伸至 110 公里。在中纬度地区，纬向风和经向风的强度相似，并且没有观察到明显的半球振幅不对称。在低热层，半日潮汐幅度呈现年度振荡，最大值为 30 至 40 m/s，出现在 6 月/7 月，北纬 35°、南纬 35°和赤道附近 100 公里处。观察到半日相位季节变化的双峰结构。这一特征的特点是快速的二分点转变，并且在赤道处尤其明显。对赤道中热层的检查表明，半日潮在 140 公里处达到最大振幅，垂直波长约为 60 公里。这些发现表明反对称 (2,3) 霍夫模式在热带地区占主导地位。
Thermospheric winds measured by the Wind Imaging Interferometer (WINDII) on the upper atmosphere research satellite are analyzed for migrating solar tides. The data cover a 2-year period commencing February 1992 and are obtained from the atomic oxygen O(1S) 557.7-nm emission, which provides observations of the 90- to 200-km altitude range during daytime and the 90- to 110-km range at night. The subtropical lower thermosphere is dominated by the diurnal propagating tide which exhibits a vertical wavelength of approximately 22 km, grows in amplitude up to 95 km, and decays rapidly above where molecular diffusion greatly reduces the vertical shears. Although the phase remains fairly uniform throughout the year, a pronounced semiannual oscillation is observed in the diurnal tide amplitude. At both 20°N and 20°S the meridional and zonal wind components attain their maximum values at equinox of approximately 70 and 40 m/s, respectively, while the solstitial minima are nearly a factor of 2 smaller. At 35°N the diurnal tide semiannual amplitude oscillation is still present in the lower thermosphere, but above 100 km it is replaced by an annual cycle with a maximum in July and August. This contrasts with 35°S where the July/August peak is absent and the semiannual oscillation extends to 110 km. At midlatitudes the zonal and meridional winds are of similar magnitude, and no significant hemispheric asymmetries in amplitudes are observed. In the lower thermosphere the semidiurnal tide amplitude exhibits an annual oscillation, with maximum values of 30 to 40 m/s occurring in June/July near 100 km at 35°N, 35°S, and the equator. A bimodal structure in the seasonal variation of the semidiurnal phase is observed. This feature is characterized by rapid equinoctial transitions and is particularly well defined at the equator. Examination of the equatorial middle thermosphere indicates that the semidiurnal tide attains its maximum amplitude at 140 km and exhibits a vertical wavelength of approximately 60 km. These findings indicate the predominance of the antisymmetric (2,3) Hough mode in the tropics.