HR: 1340h
AN: SA33A-1063    [Abstracts]
TI: Polar-Region Distributions of Poynting Flux: Global Models Compared With Observations
AU: Melanson, P D
EM: pmelanson@draper.com
AF: Dartmouth College, Thayer School of Engineering, Hanover, NH 03755, United States
AU: * Lotko, W
EM: wl@dartmouth.edu
AF: Dartmouth College, Thayer School of Engineering, Hanover, NH 03755, United States
AU: * Lotko, W
EM: wl@dartmouth.edu
AF: HAO/NCAR, 1850 Table Mesa Drive, Boulder, CO 80305, United States
AU: Murr, D
EM: murr@dartmouth.edu
AF: Dartmouth College, Thayer School of Engineering, Hanover, NH 03755, United States
AU: Gagne, J R
EM: jrg@creare.com
AF: Dartmouth College, Thayer School of Engineering, Hanover, NH 03755, United States
AU: Wiltberger, M
EM: wiltbemj@ucar.edu
AF: HAO/NCAR, 1850 Table Mesa Drive, Boulder, CO 80305, United States
AU: Lyon, J G
EM: john.lyon@dartmouth.edu
AF: Dartmouth College, Department of Physics & Astronomy, Hanover, NH 03755, United States
AB: Low-altitude distributions of electric potential, field-aligned current and Poynting flux derived from the Lyon- Fedder-Mobarry global simulation model of the magnetosphere are compared with distributions derived from SuperDARN, the Iridium satellite constellation, and the Weimer 2005 empirical model for a one-hour interval (1400-1500 UT) on 23 November 1999 during which the interplanetary magnetic field was steady and southward. Synthetic measurements along a pseudo-satellite track are also obtained from each distribution and compared with measurements from the DMSP F13 satellite. Previous studies of the event are supplemented here with updated simulation results for the electric potential and field-aligned currents, new simulation diagnostics for the Poynting flux incident on the ionosphere, and comparisons of observational and simulation results with the Weimer empirical model. The location and extent of the simulated Poynting fluxes that occur in the afternoon sector, between the Region-1 and 2 currents, are consistent with the observed and empirically modeled locations, but the magnitudes exhibit significant differences (locally up to ~100% both higher and lower). Elsewhere, the distribution of simulated fluxes more closely resembles the empirically modeled values than the observed ones and in general is greater in magnitude by about 100%. Additionally, the fraction of simulated Poynting flux that flow into the polar cap region (above 75 deg) is about one third of the total flowing into the ionosphere above 60 deg; a similar value is found for both the observed and the empirically modeled fluxes. The effect of including the parallel potential drop in the self-consistent mapping of electric potential between the ionosphere and inner boundary of the simulation domain is also examined. Globally the effect is small (< 5%); however, in regions where the field-aligned potential drop is appreciable, local changes of 100% or more are found in the magnitude of the simulated Poynting flux.
DE: 2411 Electric fields (2712)
DE: 2431 Ionosphere/magnetosphere interactions (2736)
DE: 2475 Polar cap ionosphere
DE: 2704 Auroral phenomena (2407)
DE: 2721 Field-aligned currents and current systems (2409)
SC: SPA-Aeronomy [SA]
MN: 2007 Fall Meeting