Nonmigrating tidal signals in the upper thermospheric zonal wind at equatorial latitudes as observed by CHAMP
Nonmigrating tidal signals in the upper thermospheric zonal wind at equatorial latitudes as observed by CHAMP
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DOI：
10.5194/angeo-27-2643-2009
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发表时间：
2009-07
影响因子：
1.9
通讯作者：
K. Häusler;H. Lühr
中科院分区：
文献类型：
--
作者：
K. Häusler;H. Lühr
抽象的。CHAMP上的加速计使我们能够推导出轨道高度（~400公里）的热层纬向风。大量的赤道飞越（~ 45250）被用来研究非迁移潮汐对热层纬向风的影响。在以前的研究中，一个所谓的“波-4”的纵向信号在卫星框架中观察到的纬向风残差在春分。使用四年的数据（2002-2005年），我们确定的年度变化，这是最强的7月至10月期间，并在3月/4月期间有一个较小的第二个最大值的突出功能。由于数据量大，我们能够将观测到的波数分离为潮汐分量。因此，我们可以确定向东传播的周日潮汐与纬向波数s =3（DE 3）的纬向风中所观察到的波-4型的主要原因。分析纬向风沿着的地理和倾角赤道发现，最大幅度的DE 3被发现沿倾角赤道沿着。除了DE 3，我们提出了在上层热层的非迁移潮汐的全谱。
Abstract. The accelerometer onboard CHAMP enables us to derive the thermospheric zonal wind at orbit altitudes (~400 km). Numerous equatorial overflights (~45 250) are used to investigate the influence of nonmigrating tides on the thermospheric zonal wind. In a previous study a so called "wave-4" longitudinally signal observed in the satellite frame was identified in the zonal wind residuals during equinox. Using four years of data (2002–2005), we determine the annual variation of this prominent feature which is strongest during the months of July through October and has a smaller second maximum during March/April. Due to the large data set we were able to separate the observed wavenumbers into the tidal components. Thereby, we can identify the eastward propagating diurnal tide with zonal wavenumber s =3 (DE3) as the prime cause for the observed wave-4 pattern in the zonal wind. Analyzing the zonal wind along the geographic and the dip equator revealed that the largest amplitudes of DE3 are found along the dip equator. Besides DE3 we present the full spectrum of nonmigrating tides in the upper thermosphere.