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Ann. Geophys., 15, 1205-1220, 1997
www.ann-geophys.net/15/1205/1997/
© European Geosciences Union 1997
Thermal tides and studies to tune the mechanistic tidal model using UARS observations
V. A. Yudin1, B. V. Khattatov2, M. A. Geller1, D. A. Ortland3, C. McLandress4, and G. G. Shepherd5
1Institute for Terrestrial and Planetary Atmospheres, State University of New York at Stony Brook, Stony Brook, NY 11794-5000, USA
2National Center for Atmospheric Research, Boulder, Colorado, P.O. Box 300, USA
3Space Physics Research Laboratory, University of Michigan, Ann Arbor, MI 48109, USA
4Institute for Space and Terrestrial Science, York University, Ontario, M3J 1P3, Canada
5Centre for Research in Earth and Space Science, York University, Ontario, M3J 1P3, Canada
Abstract. Monthly simulations of the thermal diurnal
and semidiurnal tides are compared to High-Resolution Doppler Imager (HRDI) and
Wind Imaging Interferometer (WINDII) wind and temperature measurements on the
Upper-Atmosphere Research Satellite (UARS). There is encouraging agreement
between the observations and the linear global mechanistic tidal model results
both for the diurnal and semidiurnal components in the equatorial and
mid-latitude regions. This gives us the confidence to outline the first steps of
an assimilative analysis/interpretation for tides, dissipation, and mean flow
using a combination of model results and the global measurements from HRDI and
WINDII. The sensitivity of the proposed technique to the initial guess employed
to obtain a best fit to the data by tuning model parameters is discussed for the
January and March 1993 cases, when the WINDII day and night measurements of the
meridional winds between 90 and 110 km are used along with the daytime HRDI
measurements. Several examples for the derivation of the tidal variables and
decomposition of the measured winds into tidal and mean flow components using
this approach are compared with previous tidal estimates and modeling results
for the migrating tides. The seasonal cycle of the derived diurnal tidal
amplitudes are discussed and compared with radar observation between 80 and 100
km and 40°S and 40°N.
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