The global geosynchronous plasma environment seen through neutral atom
imaging and local multipoint measurements

Reeves, G. D., M. G. Henderson, R. M. Skoug, M. F. Thomsen, J.-M. Jahn,
and C. J. Pollock


Geosynchronous orbit provides a rich opportunity for observing a variety
of plasma environments including the plasmasphere and the plasmasheet as
well as drainage plumes and troughs. Those environments can be
well-characterized with local, in situ measurements. Now a global view of
the near-Earth plasma environment is available from the IMAGE Medium
Energy Neutral Atom (MENA) instrument. We present the first systematic
comparison of these two rich and complementary data sources. The
comparison not only gives a global context for ENA observations of the
plasmasphere and plasmasheet but also allows direct confirmation of the
ion fluxes inferred from ENA image inversion with direct local 
measurements of those fluxes. Of course, ENA fluxes come from an integral
along the entire line of sight, not just a single near equatorial point
which turns out to be an advantage rather than a limitation. By comparing
model and observed values at the spacecraft location and at other points
along the line of sight we can obtain an estimate of the global
configuration of both the particle environment and the geomagnetic field.
This study is considerably enhanced by the recent availability of plasma
data from up to six simultaneously-operating LANL geosynchronous
satellites which provide unprecedented local time coverage in the
equatorial plane.

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To be presented at the 2002 Spring A.G.U. Meeting, 
Washington, D.C., U.S.A., 28-31 May 2002