Global Plasmaspheric Response to Varying Solar Wind-Magnetosphere Coupling

B.A. Larsen (Montana State University, Bozeman MT 59717), D.M. Klumpar, 
C.A. Gurgiolo, and B.R. Sandel 

Changes in the solar wind-magnetosphere coupling are a major driver in
magnetospheric dynamics. The plasmasphere is no exception; using inverted
IMAGE EUV data we are able to study plasmaspheric erosions, compressions,
expansions, and rotations on a global scale. The behavior of interest here
is the plasmas-pheric rotations that vary based on what is believed to be
the overlap of the co-rotation and cross-tail electric fields. The changes
in the coupling drive the co-rotation boundary toward and away from the
Earth as noted by the rotation direction of features in the EUV data.  When
solar wind coupling is low plasmaspheric features rotate in the co-rotation
direction all the way out to the visible plasmapause, while during times of
high coupling low L-shell features rotate in the co-rotation direction and
high L-shell features rotate in the anti-co-rotation direction.

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