The meridional wind component of the thermospheric tide observed by WINDII on UARS

Thermospheric meridional winds measured by the Wind Imaging Interferometer (WINDII) on the Upper Atmosphere Research Satellite (UARS) are analyzed for migrating solar tides for March/April 1993. Tidal signatures are extracted by zonally averaging and binning the data in equally spaced intervals of local time, latitude and altitude. An examination of the binned data reveals vertically propagating tides in the lower thermosphere with the diurnal tide dominating at low latitudes. Above 120 km evidence of vertical propagation ceases and the vertical gradients are significantly reduced. In regions where both daytime and nighttime data are available Fourier decomposition of the binned winds is used to extract the diurnal component of the tide. This analysis reveals that the propagating diurnal tide attains a maximum amplitude of 65 m/s at 20°N and 20°S at 95 km and exhibits a vertical wavelength of about 25 km.