WINDII Observations and WACCM‐X Simulations of High‐Latitude Winds Under Different Solar Radio Flux and Geomagnetic Disturbance Conditions
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Thermospheric zonal winds at altitudes of 140 to 250 km are shown to reverse from eastward to strong westward between 100° and 200° in geographic longitude and 60°S to 70°S latitude in the Southern Hemisphere. The reversal also occurs at the same latitude in the Northern Hemisphere, but from 200° to 340° longitude. The phenomenon has been previously described as a “wind wall.” Observations by the Wind Imaging Interferometer (WINDII) on the National Aeronautics and Space Administration's Upper Atmosphere Research Satellite (UARS) and simulations by the Whole Atmosphere Community Climate Model with thermosphere and ionosphere extension (WACCM‐X) are utilized to explore the characteristics of what has been called a wind wall. In order to study the dependence on solar radio flux and geomagnetic activity, the relationships of the maximum zonal wind and F10.7 (the solar radio flux at 10.7 cm) and ap indices are investigated. The results show that WINDII observations and WACCM‐X simulations agree well in describing this wind signature. Moreover, the appearance of the wind wall is found to have a strong dependence on the solar radio flux and geomagnetic activity. In addition, WINDII winds have a stronger response to geomagnetic activity than WACCM‐X winds.