The Plasmasphere: Fertile Ground for Application of Multiple
  Imaging Techniques

D. L. Carpenter  (Space, Telecommunications and Radioscience
  Laboratory,Stanford University, Stanford, CA 94305-9515,
  dlc@nova.stanford.edu)

The New Millennium Magnetosphere: Integrating Imaging, Discrete
  Observations, and Global Simulations, Sixth Huntsville Modeling Workshop,
  Guntersville, Alabama, 26-30 October 1998.


Plasmasphere imaging will be most successful if available knowledge
of the region is made accessible not only to those planning
experiments and pondering experimental outcomes but also to the
general science community and the interested public. In attempting
to image the plasmasphere, we must confront the region's great size a
d complexity. Topics of interest during a cycle of disturbance and
recovery include: (1) new plasmapause formation; (2) main plasmasphere
evolution in the aftermath of plasmapause formation; (3) plasma loss
from inside the newly reduced plasmasphere; (4) erosion of the
plasmasphere and the formation, movement, and disposition of outlying
plasma structures known as the bulge region; (5) recovery. These topics,
about which much remains to be learned, afford excellent imaging
opportunities to future experimenters using RPI, EUV,ENA, FUV and other
techniques on a coordinated basis. Past work using data from multiple
platforms and extensive ground and satellite data sets has set the stage
for an exciting new era of discovery. Deep density troughs in the
plasmasphere have been found, suggesting that a plasmapause can be
established in some longitude sectors near L=2 under geomagnetic
conditions normally associated with plasmapause radii near L=3 and
beyond. Outlying dense plasma structures have been found to have
unexpectedly long residence times in the distant afternoon-dusk
magnetosphere. The form of the penetrating subauroral convection
electric field during periods of plasmasphere erosion is not well
known, but its complexity is suggested by the occurrence of narrowly
channeled, substorm associated, westward directed plasma flows in the
L=3 to 4 range in the premidnight sector, called subauroral ion drifts
(SAIDs). Some comments will be made on the specific roles that can be
played by RPI, ENA, and ground radars and VLF receivers in studying
these effects as well as the broader range of topics listed above.