HR: 1340h
AN: SA33A-1055    [Abstracts]
TI: Parametrization of ion Upwelling for Auroral Precipitation
AU: * Danielides, M A
EM: michael@gi.alaska.edu
AF: Geophysical Institute University of Alaska Fairbanks, 903 Koyukuk Dr., P.O. Box 757320, Fairbanks, AK 99775-7320, United States
AU: Lummerzheim, D
EM: lumm@gi.alaska.edu
AF: Geophysical Institute University of Alaska Fairbanks, 903 Koyukuk Dr., P.O. Box 757320, Fairbanks, AK 99775-7320, United States
AU: Otto, A
EM: ao@gi.alaska.edu
AF: Geophysical Institute University of Alaska Fairbanks, 903 Koyukuk Dr., P.O. Box 757320, Fairbanks, AK 99775-7320, United States
AB: Plasma outflow into the magnetosphere is of considerable importance for mass loading of the magnetosphere. It is generally believed that ion outflow occurs in two steps, the first of which is upwelling of ions which increases the concentration of heavier ions at higher altitudes as the source population for secondary upward acceleration. In this simulation study, heating and ionization due to auroral electron precipitation is considered the main cause of for ion upwelling. The model solves neutral and ion momentum equations which include basic plasma transport coefficients, ionization and recombination terms as well as plasma-neutral collisions. The model also includes generalized Ohm's law considering self-consistent terms for resistivity, electron pressure gradients and Hall physics. The energy equations consider temperature contact terms between electrons, ions, and neutrals and the heat conduction term. Our model results demonstrate that ion upwelling is caused by pressure gradient forces due to ionization and electron heating from auroral precipitation. Softer auroral precipitation leads to larger upward fluxes and velocities because pressure gradients develop at higher altitudes in less collision dominated regions. Input parameters of the characteristic energy and the energy flux are used to parameterize properties of the ion upwelling such as particle fluxes, velocities, force densities, and acceleration.
DE: 2431 Ionosphere/magnetosphere interactions (2736)
DE: 2435 Ionospheric disturbances
DE: 2447 Modeling and forecasting
DE: 2704 Auroral phenomena (2407)
DE: 2736 Magnetosphere/ionosphere interactions (2431)
SC: SPA-Aeronomy [SA]
MN: 2007 Fall Meeting