First Attempt at Producing a 3D Plasmasphere Model from the EUV Images

Gurgiolo, C., B. Sandel, D. Gallagher

EUV measures the 30.4 nm He+ line of sight emission intensity every 10
minutes in a 600 x 150 pixel array.  The resultant 2D image primarily
probes the plasmasphere showing both its features and their time
evolution. One of the analysis goals with this data set is to deconvolve
the images to produce a 3D plasmaspheric image. There are a number of
varied and different approaches to this problem. What is presented here
is a simple approach which despite its simplicity gives reasonably
detailed results. We begin with a algorithmic plasmaspheric electron
density model. A Kp dependence controls the location of the plasmapause,
an L-Shell dependence gives a latitude variation, a single coefficient
relates the He to electron abundance and a pair of coefficients are used
to regulate the inner and outer electron density. The model is used to
create a simulated EUV image. Active feedback between the model image and
actual image results in variations in the model coefficients which bring
the model image into agreement with the actual image. The model is then
used to produce a 3D model of the He and electron density in the vicinity
of the plasmasphere. Results will be shown as interactive 3D images
allowing arbitrary cuts in magnetic coordinates to be displayed.

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To be presented at the Magnetospheric Imaging Workshop, 
Yosemite National Park, California, U.S.A., Feb. 5-8, 2002.