Seasonal behavior of the semidiurnal and diurnal tides, and mean flows at 95 km, based on measurements from the High Resolution Doppler Imager (HRDI) on the Upper Atmosphere Research Satellite (UARS)

Abstract

Derived results from the High Resolution Doppler Imager (HRDI) on UARS have provided an enormous amount of new and invaluable information, including insight into the large global seasonal variability of atmospheric tides. These and other results have given added impetus to theoretical modeling efforts, including a focus on wave‐wave and wave‐mean‐flow interactions and the resulting momentum and energy exchanges. We have extended previous analyses, and provide new results for HRDI data at 95 km using an algorithm that simultaneously generates the diurnal and semidiurnal tidal variations and the mean flows. The diurnal variations with season are quite different from those of the semidiurnal components, showing evidence of possible strong damping around the solstices, especially in the meridional winds. The mean zonal winds are eastward at equatorial latitudes, while the annual component of the mean meridional wind generally flows from the summer to the winter hemisphere. We compare our results with earlier results from HRDI and from selected models.