Storm-Time Magnetospheric Plasma Dynamics: Coordinated Ground-Based Magnetometer 
and IMAGE RPI Observations.    

Dent, Z.C., Mann, I.R., Menk, F.W., Goldstein, J., Ozeke, L.G.    

Data from the {SAMNET} ({S}ub-{A}uroral {M}agnetometer {NET}work) and {BGS}
({B}ritish {G}eological {S}urvey) arrays of ground-based magnetometers in
northern-{E}urope have been used to derive equatorial plane plasma density
profiles between L=2.4 and L=5.2. The period studied spans a number of days
pre- and post-storm, enabling the dynamics of storm-time plasmaspheric erosion
and recovery to be monitored. This interval, during May 2001, was chosen due to
the good conjunction between the IMAGE satellite and the two ground-based
magnetometer arrays. The (RPI) Radio Plasma Imager instrument on board the
IMAGE satellite provides a meaasurement of the in-situ electron density as it
passes through its orbit. Comparisons of electron and plasma mass densities
during such a conjunction can be used to examine variations of heavy ion
populations during periods of increased geomagnetic activity. The RPI
instrument observes an unusually steep plasmapause at L ~ 3 on the 14th May 
2001. Ground based magnetometers observing field lines in this region show 
unusual cross-phase results, with possible phase reversal at the plasmapause. 

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To be presented at the Western Pacific Geophysical Meeting, 
Wellington, New Zealand, 9-12 July 2002.