HR: 0800h
AN: SA31A-0344    [Abstracts]
TI: Thermospheric and Ionospheric Response to Auroral Substorms
AU: * Chua, D H
EM: damien.chua@nrl.navy.mil
AF: Naval Research Laboratory, E. O. Hulburt Center for Space Research, 4555 Overlook Ave SW, Code 7607, Washington, DC 20375 United States
AU: Budzien, S A
EM: sbudzien@ssd5.nrl.navy.mil
AF: Naval Research Laboratory, E. O. Hulburt Center for Space Research, 4555 Overlook Ave SW, Code 7607, Washington, DC 20375 United States
AU: Dymond, K F
EM: kdymond@ssd5.nrl.navy.mil
AF: Naval Research Laboratory, E. O. Hulburt Center for Space Research, 4555 Overlook Ave SW, Code 7607, Washington, DC 20375 United States
AB: Energetic particle precipitation is a significant source of ionization and thermospheric heating at high latitudes, particularly within the auroral zone. Due to the high degree of temporal and spatial variability of energetic particle precipitation during auroral substorms a large range of conditions is expected to follow in the structuring of the polar ionosphere and thermosphere in response. This is important because ionospheric irregularities that result from these perturbations are associated with phenomena such as scintillations that affect radio signals used by communications and navigation technologies. During substorms, regions of enhanced auroral particle precipitation expand in both latitude and local time over time scales ranging from tens of minutes to hours. The energy spectra of auroral particles vary greatly with local time and substorm phase. Since the particle energies determine their penetration depth in the atmosphere, the resulting ionization and heating profiles will also vary with location and time during the course of an auroral substorm. The primary objective of this study is to quantify the variability in the E and F region auroral ionosphere and the polar thermosphere in response to enhancements in particle precipitation during substorms. Polar Ultraviolet Imager (UVI) observations of the aurora will be used to characterize the horizontal spatial structure in the aurora and energetic particle precipitation during substorms. Two-dimensional maps of the precipitating electron energy flux and average energy can be inferred from UVI images. The UVI auroral images will complement coincident limb-scan observations of key, diagnostic far-ultraviolet emissions obtained by the High Resolution Airglow and Aurora Spectroscopy (HIRAAS) experiment flying on the Advanced Research and Global Observation Satellite (ARGOS). From these limb scans we derive altitude and latitude profiles of electron and neutral density across a common swath of the aurora observed by Polar UVI. These measurements will allow us to quantify the variation of E and F region electron density altitude profiles, total electron content, and neutral density altitude profiles as a function of precipitating electron energy flux and average energy. We will therefore obtain a quasi-three dimensional picture of variations in the auroral ionosphere and polar thermosphere before, during, and after substorm events.
DE: 2427 Ionosphere/atmosphere interactions (0335)
DE: 2437 Ionospheric dynamics
DE: 2455 Particle precipitation
DE: 2736 Magnetosphere/ionosphere interactions (2431)
DE: 7949 Ionospheric storms (2441)
SC: SPA-Aeronomy [SA]
MN: Fall Meeting 2005