Ring Current Buildup and Decay: IMAGE Observation and Theory

M.C. Fok 1  (301-286-1083; mei-ching.fok@gsfc.nasa.gov)
J. Goldstein 2, T.E. Moore 1, R.L. Lambour 3, J.W. Freeman 2, and J.L. Burch 4

1 Laboratory for Extraterrestrial Physics, NASA Goddard Space Flight
  Center, Code 692, Greenbelt, MD 20771, USA)
2 Physics and Astronomy Department, Rice University, Houston, TX 77005, USA
3 MIT Lincoln Laboratory, 244 Wood Street, Lexington, MA 02420, USA
4 Southwest Research Institute, Space Science Department, San Antonio,
  TX 78238, USA

During the main phase of the magnetic storm on May 24, 2000, images
from the IMAGE EUV plasmasphere imager revealed a shoulder-like
feature in the dawn-noon sector and a plasma tail sweeping from dusk
to the dayside.  At the same time, IMAGE HENA imager observed
depletion of ring current ions in these enhanced plasmasphere
regions.  These coexisting features strongly suggest that the cold
plasma background has an important role in the decay of the hot ring
current.  We will quantify the effect of hot-cold interactions on
ring current decay by running a kinetic model of the ring current and
simultaneously the MSM plasmasphere model, which has successfully
reproduced the plasmaspheric shoulder and tail features.  Besides the
storm on May 24, 2000, we will study other periods of good EUV-
neutral atom data coverage to examine our current theory of hot-cold
interaction with IMAGE observations.

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Submitted to the Spring 2001 AGU Meeting, Boston, Massachusetts