Low-frequency fluctuations in the magnetosheath near the magnetopause

Journal Article · Sat Apr 01 04:00:00 EST 1995 · Journal of Geophysical Research

DOI:https://doi.org/10.1029/94JA03024· OSTI ID:166209

Denton, R E; Li, X; LaBelle, W ^[1]

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1. Darthmouth College, Hanover, NH (United States); and others

There are four low-frequency modes which may propagate in a high-beta nearly bi-Maxwellian plasma. These are the magnetosonic, Alfven, ion acoustic, and mirror modes. This manuscript defines a procedure based on linear Vlasov theory for the unique identification of these modes by use of transport ratios, dimensionless ratios of the fluctuating field and plasma quantities. A single parameter, the mode deviation, is defined which characterizes the difference between the theoretical transport ratios of a particular mode and the observed ratios. The mode deviation is calculated using the plasma and magnetic field data gathered by the Active Magnetospheric Particle Tracer Explorers/Ion Release Module spacecraft to identify the modes observed in the terrestrial magnetosheath near the magnetopause. As well as determining the mode which best describes the observed fluctuations, it gives the authors a measure of whether or not the resulting identification is unique. Using 17 time periods temporally close to a magnetopause crossing, and confining their study to the frequency range from 0.01 to 0.04 Hz, they find that the only clearly identified mode in this frequency range in the mirror mode. Most commonly, the quasi-perpendicular mirror mode (with wave vector k roughly perpendicular to the background magnetic field B{sub 0}) is observed. In two events the quasi-parallel mirror mode (k{parallel}B{sub 0}) was identified. 36 refs., 4 figs.

• OSTI ID: 166209
• Journal Information: Journal of Geophysical Research, Journal Name: Journal of Geophysical Research Journal Issue: A4 Vol. 100; ISSN JGREA2; ISSN 0148-0227
• Country of Publication: United States
• Language: English

Related Subjects

66 PHYSICS
ALFVEN WAVES
FLUCTUATIONS
ION ACOUSTIC WAVES
LONG WAVE RADIATION
MAGNETOACOUSTIC WAVES
MAGNETOPAUSE
MAGNETOSHEATH
MILLI HZ RANGE
OSCILLATION MODES