HR: 1330h
AN: SH42A-0495    [PDF]
TI: Climatology of nighttime mid and low latitude upper thermospheric disturbance winds measured by WINDII
AU: * Emmert, J T
EM: emmert@uap2.nrl.navy.mil
AF: E. O. Hulburt Center for Space Research, Naval Research Laboratory 4555 Overlook Ave., SW, Washington, DC 20375
AU: Fejer, B G
EM: bfejer@cc.usu.edu
AF: Center for Atmospheric and Space Science, Utah State University 4405 Old Main Hill, Logan, UT 84322
AU: Shepherd, G G
EM: gordon@yorku.ca
AF: Centre for Research in Earth and Space Science, York University, Toronto, ON M3J 1P3 Canada
AU: Solheim, B H
EM: bsolheim@yorku.ca
AF: Centre for Research in Earth and Space Science, York University, Toronto, ON M3J 1P3 Canada
AB: Neutral dynamics directly impact the structure of the thermosphere and ionosphere, but the global characteristics of neutral winds under disturbed conditions are poorly understood. We use measurements from the Wind Imaging Interferometer (WINDII) on board the Upper Atmosphere Research Satellite (UARS) to study the climatology of nighttime mid and low latitude upper thermospheric disturbance winds induced by geospace storms. Previous analyses of WINDII disturbance winds have focused on the daytime sector. Our climatology represents a disturbed condition of Kp $\sim$ 4. At geomagnetic latitudes of 65\deg, strong westward perturbation winds are observed in the dusk sector, peaking near 1700 LT with values of 160 m/s. At lower latitudes, these westward disturbances are weaker and develop later; at 35\deg, they peak near midnight with values of 30 m/s. Near the geomagnetic equator, westward perturbations of 20 m/s are observed at 2200 LT; these shift to eastward at ~0100 LT. A west-to-east reversal is also observed at this local time at latitudes above 50\deg, whereas the post-midnight westward disturbance winds at midlatitudes merely diminish with increasing local time. Equatorward perturbation winds are observed after 2000 LT at geomagnetic latitudes from 40\deg to 65\deg. These peak around 0300 LT with values of 50 m/s. At lower latitudes, smaller equatorward disturbances appear after 0200 LT, with magnitudes less than 20 m/s. We also investigate the seasonal and solar cycle dependence, and we compare our results with midlatitude disturbance winds derived from Millstone Hill Fabry-Perot interferometer measurements.
DE: 0358 Thermosphere--energy deposition
DE: 2427 Ionosphere/atmosphere interactions (0335)
DE: 3369 Thermospheric dynamics (0358)
SC: SPA - Solar and Heliospheric Physics [SH]
MN: 2003 Fall Meeting