HR: 15:10h
AN: SM52C-06    [PDF]
TI: In-Situ and Ground-Based Intercalibration Measurements of Plasma Density at L=2.5
AU: * Clilverd, M A
EM: m.clilverd@bas.ac.uk
AF: Mark A Clilverd, British Antarctic Survey, Cambridge, CB3 0ET United Kingdom
AU: Menk, F W
AF: Fred W Menk, School of Mathematical and Physical Sciences and Cooperative Research Centre for Satellite Systems, University of Newcastle, Callaghan, 2308 Australia
AB: Two independent ground-based experiments and two satellite-borne experiments are used to inter-calibrate the instruments, and interpret the changes in plasmaspheric composition at the same point in space during a range of geomagnetic activity in 2001 and 2002. Mass density at L=2.5 was determined from an array of magnetometers on the Antarctic Peninsula, while the electron number density along the same flux tube was determined from analysis of the group delay of man-made VLF transmissions from north-east America. The IMAGE satellite RPI experiment provided in-situ measurements of the electron number density in passing the equatorial region of the same field line, while the IMAGE EUV experiment was able to resolve the He+ abundance by looking back toward the same place a few hours later. With a moderately-disturbed plasmasphere, at Antarctic Peninsula longitudes, electron and ion concentrations show good agreement on specific study days. He+ column abundance values of 6 x 10$^{10}$ cm$^{-2}$ are found to be equivalent to plasmaspheric electron density levels of 3000 cm$^{-3}$ at L=2.5. For these conditions the He+ mass abundance was about 12-16% compared with H+. The work has been extended to severely-disturbed plasmasphere conditions, also studied at Antarctic Peninsula longitudes, and we present results which are compared with less disturbed times in terms of He+ column abundance, electron number density profiles, and heavy ion mass abundance. Insight is gained in the interpretation of the effects of severe geomagnetic storms on long-term data sets derived from ground-based VLF whistler-mode experiments.
DE: 2768 Plasmasphere
DE: 2788 Storms and substorms
DE: 6964 Radio wave propagation
DE: 7867 Wave/particle interactions
SC: SPA - Magnetospheric Physics [SM]
MN: 2003 Fall Meeting