Some results of comparison between the lower thermosphere zonal winds as seen by the ground-based radars and WINDII on UARS

The seasonal variations of the zonal winds measured by meteor/MF radars and by the wind-imaging interferometer (WINDII) on board of the UARS satellite , are analyzed and compared with the ground-based Global Empirical Wind Mod el (GEWM) and satellite-based WINDII prevailing wind model, which are indep endently derived from the observational data sets. A general consistency in the main global scale wind structures is observed. The seasonal variations of zonal wind in the both models are described by almost the same annual a nd semi-annual components. But systematic bias is found for the annual mean zonal winds of the two models, with the GEWM winds generally smaller than those of WINDII by factor 2-2.5. This bias is practically independent of al titude and can be described by a term of A cos 4x, where A is about 20 m/s and x is colatitude. Possible origin of this offset is discussed.