Comparison of the auroral E region neutral winds derived with the European Incoherent Scatter radar and predicted by the National Center for Atmospheric Research Thermosphere-ionosphere-mesosphere-electrodynamics general circulation model

A comparison study of the auroral E region neutral wind has been conducted using the European Incoherent Scatter (EISCAT) radar observations and Thermosphere-Ionosphere-Mesosphere-Electro dynamics general circulation model (TIME GCM) predictions. The daily mean wind data as well as diurnal and semidiurnal tidal wind data, are compared for the three seasons summer, equinox, and winter between 95 and 119 km. Fairly good agreement is found in the altitude profile of the mean zonal wind between the EISCAT observation and the TIME GCM prediction for summer, indicating the parameterization of gravity waves employed in the TIME GCM is adequate for this feature. The meridional mean wind amplitude predicted by the TIME GCM is considerably smaller than that observed by EISCAT, and the predicted wind is slightly northward for all the seasons above 100 km. Generally good agreement is found for the amplitude of the diurnal tide, especially the summer prediction, while disagreements between the model and observational results are found for the corresponding phases. The semidiurnal amplitude predicted by the TIME GCM is much smaller than that observed by EISCAT, and relatively large differences of the semidiurnal phase between the observations and predictions are found for all seasons. These comparison results suggest that further advancements in the gravity wave parameterization, as well as the addition of planetary wave effects, are needed to predict more realistic lower thermospheric winds at high latitude.