Average daytime F region disturbance neutral winds measured by UARS: Initial results

Thermospheric neutral winds play important roles on the dynamics of the upp er atmosphere. We use extensive F region zonal and meridional wind data mea sured by the Wind Imaging Interferometer (WINDII) instrument on board the U pper Atmosphere Research Satellite (UARS) to study the mid- and low-latitud e daytime average perturbation winds during magnetically disturbed periods. We have determined the perturbation winds by subtracting the quiet time wi nd values along the satellite orbits. Our data indicate large changes in th e latitudinal profiles of both the zonal and meridional disturbance winds f rom morning to afternoon hours. The early morning zonal disturbance winds a re eastward near the equator and at upper mid-latitudes (above 50 degrees), and westward at lower mid-latitudes. The mid-morning and afternoon zonal d isturbance wind patterns show very small amplitudes at low latitudes and in creasing westward winds at mid-latitudes. These latitudinal profiles are in excellent agreement with the patterns derived from zonal wind measurements on board the DE-2 satellite. The meridional daytime perturbation winds are equatorward and have magnitudes increasing linearly with latitude, with la rgest values in the early morning sector. The zonal and meridional disturba nce winds show an approximately linear increase with the Kp index during ge omagnetically active conditions.