Planetary scale and tidal perturbations in mesospheric temperature observed by WINDII

WINDII, the Wind Imaging Interferometer on the Upper Atmospheric Research S atellite measures winds and emission rates from selected excited metastable species. Here we report on measurements of the atmospheric Rayleigh scatte ring from the O(S-1) background filter at 553 nm wavelength used to derive temperature profiles in the upper mesosphere from 70 km to 95 km, for solst ice periods from December 1992/93 and January 1993/94. The data are first z onally averaged and then combined in local time over about one month. Based on these temperatures, an analysis of planetary wave structures and tidal perturbations employing least-mean-square (LMS) fits to the data has been c onducted and the results are presented. The planetary wave structures obser ved were well described with a quasi two-day wave (QTDW). Amplitudes of 14 K and 10 K at 85 km height for downleg (descending) and upleg (ascending) s ampling respectively at latitudes from 20 degrees S to 40 degrees S were fo und to be in good agreement with QTDW temperature results from the MLS/UARS experiment assuming a vertical amplitude structure of the type described b y the HRDI/UARS mesospheric wind observations. It is shown that the diurnal tide amplitudes estimated from latitudes from 25 degrees N to 35 degrees S using the LMS fit maximize at the equator with an amplitude of about 6 K a nd decrease toward tropical latitudes, consistent with the classical tidal theory and predictions from the TIME-GCM model.