HR: 15:00h
AN: SA23B-05    [Abstracts]
TI: Modeling Suspersonic Flow in the High-Latitude Thermosphere
AU: * Demars, H G
EM: demars@cc.usu.edu
AF: Utah State University, Center for Atmospheric and Space Sciences 4405 Old Main Hill, Logan, UT 84322-4405, United States
AU: Schunk, R W
EM: schunk@cc.usu.edu
AF: Utah State University, Center for Atmospheric and Space Sciences 4405 Old Main Hill, Logan, UT 84322-4405, United States
AB: Supersonic flow has been observed in the high-latitude thermosphere via DE-2 satellite measurements. The supersonic flow events were observed to occur most frequently in the dawn sector at high magnetic latitudes and in the altitude range from about 300-600 km. To gain theoretical insight into these supersonic flow events, we used a high-resolution model of the global thermosphere to study the geophysical conditions that give rise to supersonic flow. In particular, we considered the dependence of the neutral wind on IMF orientation, magnetic activity level, convection pattern shape, solar activity level, season, and universal time. We also studied the extent to which narrow plasma convection channels can induce supersonic neutral winds. We found that the predominant factor controlling the thermospheric wind speed at high latitudes is the magnitude of the cross- polar-cap potential, indicating that interaction with the convecting ionosphere can drive the thermosphere to supersonic speeds. The region of supersonic flow predicted by the model corresponds closely to the region where supersonic flow events were most frequently observed by the DE satellite.
DE: 2427 Ionosphere/atmosphere interactions (0335)
DE: 3367 Theoretical modeling
DE: 3369 Thermospheric dynamics (0358)
SC: SPA-Aeronomy [SA]
MN: 2007 Fall Meeting