Climatology of midandlow-latitude F region disturbance winds measured by WINDII

We have modeled the global climatology of middle- and low-latitude F region daytime disturbance neutral winds using extensive measurements by the Wind Imaging Interferometer (WINDII) instrument on board the UARS. The perturbation winds were obtained by subtracting the quiet time values from the disturbed winds along the satellite orbit, which effectively removes average measurement bias. The zonal disturbance winds are mostly westward (except in the early morning sector), increase with latitude, and have largest values in the late afternoon sector. In general, the meridional perturbation winds are equatorward, increase linearly with latitude, and decrease from early morning to afternoon hours. The zonal and meridional perturbations increase roughly linearly with Kp and expand to lower latitudes with increasing magnetic activity. The meridional disturbance winds are largest for low solar flux conditions. We present empirical analytical models for longitudinally averaged disturbance winds from 60° to the equator. Our model winds are in poor agreement with results from the empirical wind model Horizontal Wind Model-93 during the entire daytime period. There are also important discrepancies between the average perturbations winds from WINDII and the National Center for Atmospheric Research thermosphere-ionosphere electrodynamic general circulation model, particularly at midlatitudes. These differences could be explained in part by the storm time dependence of the disturbance winds and by the variability of the high-latitude electric fields