HR: 0830h
AN: SM51B-0517 [PDF]
TI: Impact of Global Averaging on UVI-based B$_Z$ North Conductance Estimates
AU: * Doe, R A
EM: doe@sri.com
AF: SRI International, 333 Ravenswood Avenue, Menlo Park, CA 94025 United States
AU: Semeter, J L
EM: joshua.semeter@sri.com
AF: SRI International, 333 Ravenswood Avenue, Menlo Park, CA 94025 United States
AU: Lummerzheim, D
EM: lumm@gi.alaska.edu
AF: Geophysical Institute, UAF, 903 Koyukuk Drive, Fairbanks, AK 99775 United States
AU: Germany, G
EM: germanyg@cspar.uah.edu
AF: CSPAR, University of Alabama, S131 Technology Hall, Huntsville, AL 35899 United States
AB:
Dual Lyman-Birge-Hopfield (LBH) band images from the POLAR satellite UVI instrument are used herein to investigate global
conductance morphology for B$_Z$ north conditions. An automated data miner was used to nominate candidate LBH images and to
correct individual images for UV dayglow. High apogee LBH band images from three successive winter epochs (1997 - 1999) were
selected for periods when B$_Z$ was greater than 2 nT for at least 30 minutes. This B$_Z$ selection criteria was chosen to
avoid the variability associated with substorm onset/recovery and to allow the polar ionosphere a significant response time
to quiescent magnetospheric forcing. Approximately 2000 image pairs survived selection and were used to estimate global maps
for Hall and Pedersen conductance (mean and variance) as a function of By polarity. Two methods were used to create mean and
variance conductance maps. In the first method, LBH brightness maps in Rayleighs, assembled for the entire B$_Z$ north
image ensemble, were used with a neutral atmosphere model to calculate conductance. These brightness maps
indicate a B$_Y$-dependent variance structure in agreement with modeled and observed morphology of polar cap arcs. The second
method calculates conductance on an individual image-by-image basis and forms means and variances on an ensemble of
conductance maps. A comparison of both methods will be used to assess the most appropriate for use with highly dynamic and
structured storm/substorm images.
DE: 2716 Energetic particles, precipitating
DE: 2736 Magnetosphere/ionosphere interactions
DE: 2740 Magnetospheric configuration and dynamics
DE: 2776 Polar cap phenomena
DE: 2794 Instruments and techniques
SC: SPA - Magnetospheric Physics [SM]
MN: 2003 Fall Meeting