Studies of thermospheric neutral winds utilizing ground-based optical and radar measurements

The neutral dynamics of the F-region and the lower thermosphere have been investigated through extensive ground-based measurements.;Ground-based Fabry-Perot Interferometers at Thule Air Base (76.5;Careful treatment is used in analyzing the (OI) 5577 A measurements because of the possible contamination from auroral emission and weak F-region emission. The ambiguity in the altitude of the emission layer is removed by eliminating data with relatively high signal intensity, because the auroral emission contribution is always much greater than the nightglow. The contribution originating from the upper layer to the measured winds has been quantified by performing a computer simulation. The simulation results indicate that the measured winds at Thule may have a substantial diurnal oscillatory component from the F-region. The same simulation shows negligible F-region contamination for Sondre Stromfjord winds. Tidal information is extracted from the averaged winds and compared with radar measurements in similar locations and model output.;The global structure of lower thermospheric dynamics is investigated utilizing a comprehensive data base of lower thermospheric wind measurements. Data are assembled from various radar systems. The data, together with FPI measurements, are used to develop an empirical model of global lower thermospheric diurnal and semidiurnal tidal oscillations. The amplitudes of tidal oscillations generally increase with height in the lower thermospheric region.