The Evolution and Morphology of Plasmaspheric Low-Density Channels

M.L. Adrian (University of Alabama in Huntsville, Huntsville, AL  35899) and
D.L. Gallagher

Historically, in-situ observation of the plasmasphere has revealed the
existence of deep density troughs radially inside the plasmapause in which 
the electron density is depleted by a factor of ~2 to 10 below that of nearby
plasmaspheric values.  While in-situ observations have defined the radial
structure of embedded plasmaspheric troughs and provided insight into their
dependence on geomagnetic conditions, in-situ observations have been unable 
to address questions concerning the origins and azimuthal extent of these
features.

We present a survey of IMAGE EUV data from 24 May 2000 through 02 October 
2002 in which low-density plasmaspheric channels were detected in ~18% of 
the available data.  The evolution across all magnetic local time sectors,
morphology, and geomagnetic dependence of plasmaspheric channels will be
presented in the context of prior in-situ measurements.  It will be
demonstrated that the EUV-observed low-density channels are the global
extension of previously reported in-situ troughs.  Together with correlative
in-situ observations made by Polar, we demonstrate the morphological
distinction between low-density channels and plasmapause notches present
within previously reported in-situ trough observations.

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Presentation at the Yosemite Conference of Inner Magnetospheric Interactions,
3 - 6 February 2004, Yosemite, California, USA