HR: 0830h
AN: SM51C-0547    [PDF]
TI: Electron Density Profiles in the Plasmapause and Plasma Trough Regions
AU: * Laakso, H
EM: Harri.Laakso@esa.int
AF: ESA, Code SCI-SH, Postbus 299, Noordwijk, 2200 AG Netherlands
AU: Masson, A
EM: Arnaud.Masson@esa.int
AF: ESA, Code SCI-SH, Postbus 299, Noordwijk, 2200 AG Netherlands
AB: The Polar satellite has passed through the inner magnetosphere more than 5,000 times, crossing the plasmapause region more than 10,000 times (quite often four times per 18-hr orbit). Using the electron densities provided by the EFI experiment, we study statistically the density variation at L = 3-12 shells. With a power law fitting, we determine the plasmapause (PP) location and thickness, and the power law slope of density in the trough region. All characteristics reveal strong variation with MLT and Kp. The average PP location moves from L = 5 to L = 3.5 with increasing Kp. For any Kp, however, the MLT dependence is clear. For instance, the plasmaspheric bulge turns noonward with increasing Kp, and interestingly large PP distances also occur around 9 MLT sector. The PP thickness decreases with increasing Kp from 0.7 L to 0.1 L. However, at 12-21 MLT the PP thickness tends to remain always quite large (0.4-0.8). The trough power law index $k$ (density is proportional to $L^{-k}$) shows interesting and strong behavior with MLT and Kp; for instance, in the post-midnight sector $k$ decreases from 5 to 3 with increasing Kp whereas in the pre-midnight sector the change occurs between 4 and 3. Near noon $k$ is 2.5 for all Kp conditions. In the plasmapause and trough region, small-scale irregularities are quite common, and we attempt to characterize their occurrence and characteristics with MLT and Kp.
DE: 2411 Electric fields (2712)
DE: 2730 Magnetosphere--inner
DE: 2760 Plasma convection
DE: 2768 Plasmasphere
SC: SPA - Magnetospheric Physics [SM]
MN: 2003 Fall Meeting