HR: 1330h
AN: SA13A-05    [Abstracts]
TI: Thermosphere Density and Wind Responses During Severe Magnetic Storms from CHAMP and GRACE Accelerometer Measurements
AU: * Sutton, E K
EM: eric.sutton@colorado.edu
AF: Department of Aerospace Engineering Sciences; University of Colorado - Boulder, 429 UCB, Boulder, CO 80309 United States
AU: Forbes, J M
EM: Forbes@colorado.edu
AF: Department of Aerospace Engineering Sciences; University of Colorado - Boulder, 429 UCB, Boulder, CO 80309 United States
AU: Nerem, R S
EM: Nerem@colorado.edu
AF: Department of Aerospace Engineering Sciences; University of Colorado - Boulder, 429 UCB, Boulder, CO 80309 United States
AB: Measurements of atmospheric density and winds near 410 km from the STAR accelerometer on the CHAMP satellite and near 490 km from the STAR accelerometers on the GRACE satellites are used to illustrate the spatial-temporal dependence of the thermospheric response to solar/geomagnetic storms. The storm studied here is the Oct/Nov 2003 severe storm events. This interval includes periods of elevated magnetic activity with k_P values of 5-9. Measurements made by the CHAMP satellite are available from -87° to +87° latitude during both night and day at local times near 01:00 and 13:00 hours, while measurements made by the GRACE satellites are available from -89° to +89° latitude at local times near 04:00 and 16:00. During times of geomagnetic activity, density measurements exhibit enhancements of 200-300%. Northern hemisphere day-time responses are much larger than in the Southern hemisphere; the origins of this effect are unknown. Night-time density disturbances more readily propagate to equatorial latitudes at night, possibly facilitated by the predominant equator-ward flow in both hemispheres due to the diurnal tides driven by in-situ EUV heating. The CHAMP density measurements are compared with density predictions from the NRL-MSISe-00 empirical density model, and demonstrate some model shortcomings. Measurements of cross-track accelerations also provide the opportunity to estimate zonal winds from the equator to about ± 60° latitude, transitioning to a measure of purely meridional winds at the turning point of the orbit near ± 87° and ± 89° latitude for the CHAMP and GRACE missions, respectively. These horizontal components are compared to the thermospheric Horizontal Wind Model (HWM-93). The GRACE satellites also provide radial axis accelerometry which can be used to estimate vertical winds.
UR: http://suttonek.000k2.com
DE: 0358 Thermosphere--energy deposition
DE: 2427 Ionosphere/atmosphere interactions (0335)
DE: 3369 Thermospheric dynamics (0358)
SC: SPA-Aeronomy [SA]
MN: 2005 Joint Assembly