EUV Observations of the Structure and Dynamics of the Plasmasphere

Sandel, B. R., J. Goldstein, D. L. Gallagher, D. L. Carpenter

The Extreme Ultraviolet Imager (EUV) of the IMAGE Mission records the
distribution of He+ in the plasmasphere with a time resolution of 10 
minutes and a spatial resolution of 0.1 RE. Each image encompasses all or 
most of the plasmasphere, to permit study of the structure and dynamics 
of the plasmasphere in its entirety. The images reveal a host of distinct
plasmaspheric features and behaviors. Many of these had already been
inferred during the more than three decades of investigations of the
plasmasphere using ground-based and in situ techniques, but some of them
appear to be new and unexpected. Our new global images also provide a
context that is helpful in interpreting contemporary in situ measurements.

Here we survey features of the plasmasphere as seen by EUV and suggest
relationships among them. We place the EUV images in the context of 
earlier measurements. In reviewing recent results, we emphasize 
correlative studies with other observations and comparisons with models 
of the magnetosphere and plasmasphere. 

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