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Kawano et al. 2006
Kawano, H., Chi, P.J., Kumamoto, A. and Morioka, A. (2006). In situ observation at L = 2.3–5 by the Akebono satellite of the plasmaspheric depletion during the September 1998 magnetic storm. Journal of Geophysical Research 111: doi: 10.1029/2005JA011134. issn: 0148-0227.

From ground-based observations at L = 2.07 of the field line resonance (FLR) during an intense magnetic storm on 25 September 1998, Chi et al. (2000) estimated that the equatorial plasma density at L = 2.07 dropped to 25% of the prestorm value. Such depletion very close to the Earth is unusual. Two possible interpretations of the result are: (1) the plasmapause moved inward past L = 2.07, and (2) the plasmapause remained outside L = 2.07, but the density within the plasmasphere decreased. To distinguish between these possibilities, we examine in situ observations of the electron density made by the Akebono satellite at L = 2.3--5 on four passes during the same storm. The electron density measured by Akebono at a reference L shell of L ~2.5 changed with time in a manner consistent with the FLR-based estimates. On three of these passes, the plasmapause was located at L > 3, and if the plasmaspheric L profile of the Akebono density data is extrapolated inward, for each pass, its value at L = 2.07 matches the FLR-based estimates. However, on the pass at 2323--2351 UT on 25 September that corresponded to the severe density decrease detected at L = 2.07, Akebono did not detect a plasmapause in the L range (>2.3) for which the electron density data were available. For the same pass, inward extrapolation of the density measured at L > 2.3 was a factor of ~5 smaller than the FLR-based estimate. This implies that there was a sharp density inward gradient (the plasmapause) at 2.07 < L < 2.3, supporting the second interpretation.

BACKGROUND DATA FILES

Abstract

Keywords
Magnetospheric Physics, Plasmasphere, Space Weather, Magnetic storms, Magnetospheric Physics, Magnetospheric configuration and dynamics, Radio Science, Remote sensing
Journal
Journal of Geophysical Research
http://www.agu.org/journals/jb/
Publisher
American Geophysical Union
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