HR: 16:00h
AN: SH52B-01 INVITED     [PDF]
TI: Response of the Low Latitude Thermosphere and Ionosphere to Geomagnetic Storms
AU: * Fuller-Rowell, T
EM: tim.fuller-rowell@noaa.gov
AF: NOAA Space Environment Center and CIRES University of Colorado, 325 Broadway, Boulder, CO 80305 United States
AU: Maruyama, N
AF: High Altitude Observatory, NCAR, Boulder, CO 80307 United States
AU: Richmond, A
AF: High Altitude Observatory, NCAR, Boulder, CO 80307 United States
AU: Codrescu, M
AF: NOAA Space Environment Center and CIRES University of Colorado, 325 Broadway, Boulder, CO 80305 United States
AU: Millward, G
AF: Atmospheric Physics Lab, University College London, London, WC1 United Kingdom
AB: Electrodynamics dominates the structure of the low latitude ionosphere. During a storm, equatorial electric fields are severely disrupted by a combination of magnetospheric penetration and neutral wind dynamo electric fields. The result is a dramatic change in the plasma structure and the local-time occurrence of plasma irregularities. Numerical simulations using a coupled thermosphere, ionosphere, plasmasphere, electrodynamic model have been used to unravel the complex storm-time response of the upper atmosphere, and aid in the understanding and interpretation of the phenomena. Contrary to previous expectations, the dynamo action of the neutral winds can be large and rapid, and follow closely behind the penetration fields. The rapid dynamo fields are forced by the meridional wind surges that drive zonal Pedersen currents, causing charges to build up at the terminators that immediately leak to the equator. The global wind system is highly dynamic during these disturbances as winds "slosh" from one hemisphere to the other. The electrodynamics responds quickly to the dynamics and exhibits rapid and large changes in the electric fields and in the equatorial plasma distribution. If the dynamo and penetration electrodynamic processes act constructively, plasma at the magnetic equator can be completely decimated and the anomaly peaks can move well into mid-latitudes.
DE: 2415 Equatorial ionosphere
DE: 2427 Ionosphere/atmosphere interactions (0335)
DE: 2447 Modeling and forecasting
SC: SPA - Solar and Heliospheric Physics [SH]
MN: 2003 Fall Meeting