The Plasmasphere Boundary Layer (PBL); A New Framework for Study of the
Plasmapause/Plasmasphere

D.L. Carpenter (Stanford University, Stanford, CA 94305) and J. Lemaire

Boundary layers can form in space at interfaces between regions with
different plasma characteristics, examples being the LLBL and the PSBL. We
suggest that there is a plasmasphere boundary layer or PBL, associated with
the interface between the hot plasmas of the plasma sheet and the cool
plasmas of the inner magnetosphere. This is not a new concept; most
experimenters who have studied the plasmasphere have recognized its
complexity and the fact that the physics involved in its formation and
reformation cannot be reduced to discussions of equipotential surfaces in
the equatorial plane, as is common in textbooks and in classroom lectures.
The PBL concept is offered as a framework for discussing phenomena such as
shielding of the plasmasphere from high-latitude electric fields, plasma
sheet/ionosphere coupling in the nighttime sector, fast westward plasma
drifts near the ionospheric projection of the plasmapause, upward and
downward ionization flows, irregularities in the plasmapause density
profile, interchange motions, erosion of  the plasmasphere, heat flow from
the plasmasphere to the ionosphere and vice versa,  etc. The PBL concept is
liberating, in that it provides an improved basis for organizing and
promoting discussions of a variety of interrelated phenomena that take place
within and near the outer plasmasphere and in associated ionospheric regions.

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