Paper#: 122
Poster #: 20
Session Name: Poster Session 2
Room: East Ballroom
Day: Thursday
Time: 10:10 a.m.-Noon
Abstract Title: Comparison of Plasma Sheet and Auroral Electron Energy Fluxes during Substorms
PresentSurname: Fillingim, M.O.
All Authors: M.O. Fillingim, G. K. Parks, D. Chua, R. P. Lin
Abstract : Using both global auroral images and in-situ particle measurements, we quantitatively compare the downgoing electron energy flux in the plasma sheet with the electron energy flux into the auroral ionosphere with respect to substorm phase. We find that during quiet times, the downgoing energy flux in the plasma sheet mapped down to ionospheric altitudes is comparable to the energy flux observed in the aurora. During intervals of intense auroral emission such as substorm onset and expansion, the electron spectra in the conjugate region of the plasma sheet harden, increasing the downgoing energy flux. However, the increase in the plasma sheet energy flux is not enough to account for the increased energy flux into the ionosphere by up to an order of magnitude. This is consistent with the idea that additional energy flux is entering the loss cone through the presence of parallel electric fields above the ionosphere during intervals of intense auroral emission. As auroral activity decreases during recovery, the electron distributions in the plasma sheet become strongly field aligned up to energies of several keV. The downgoing plasma sheet electron energy flux nearly sufficiently accounts for the diffuse auroral luminosity. Our results show that although large changes in the plasma sheet electron distributions occur at substorm onset, lower altitude processes are dominant in producing the observed auroral energy flux. These low altitude processes decrease in importance throughout the recovery phase.