Alfvén waves and Poynting flux observed simultaneously by Polar and FAST in the plasma sheet boundary layer

J. Dombeck, C. Cattell, J. R. Wygant, A. Keiling, J. Scudder

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Abstract

We present the first simultaneous observations of Alfvén waves at Polar and FAST altitudes, ∼7 RE geocentric and ∼3500 km, respectively, at ∼23 MLT in the main phase of a major geomagnetic storm on 22 October 1999. We compare the Poynting flux for these waves and the electron energy flux at the two spacecraft. We also present a new method of Alfvén wave analysis, examining Poynting flux magnitude and directionality along with the perturbation electric to magnetic field ratio of these waves as a function of wave temporal scale (frequency). The results of this analysis are compared with those expected from kinetic Alfvén wave models. There is a mean net loss of ∼2.1 ergs cm-2 s-1 (mW m-2) in earthward Poynting flux over the altitude region between Polar and FAST, a mean net increase in earthward electron energy flux of up to ∼1.2 ergs cm -2 s-1 over the same region, frequency characteristics consistent with a mixture of Alfvén waves obeying the kinetic Alfvén wave dispersion relation mixed with some coupling to the ionosphere, and high-frequency kinetic Alfvén wave generation between Polar and FAST. Current models are found to be generally consistent with the study results but are not yet sufficiently well formulated to account for the details, including evidence for temporal and/or spatial modulation of reflectivity.

Original languageEnglish (US)
Article numberA12S90
JournalJournal of Geophysical Research: Space Physics
Volume110
Issue numberA12
DOIs
StatePublished - 2005

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