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Title: Magnetic pulsations from 0. 1 to 4. 0 Hz and associated plasma properties in the earth's subsolar magnetosheath and plasma depletion layer

Abstract

Dynamic spectral analysis covering frequencies 0.1 to 4.0 Hz has been applied to analyze Active Magnetospheric Particle Tracer Explorers CCE magnetic field data during periods of magnetospheric compressions when the spacecraft sampled the magnetosheath. Ion (H[sup +], He[sub 2+]) and electron data are used to identify regions, to monitor the upstream shock geometry, and to evaluate moments of the proton distribution. For quasi-perpendicular shock conditions, two distinctive band limited spectral types are found to characterize the majority of magnetosheath observations: (1) purely compressional fluctuations with F < 0.2 F[sub H][sup +] which are attributed to mirror waves (F and F[sub H][sup +] denote the wave frequency and proton gyrofrequency, respectively); and (2) 0.25-1.0 F[sub H][sup +] frequency purely transverse fluctuations that are often left hand polarized from 0.5-1.0 F[sub H][sup +] and are attributed to electromagnetic ion cyclotron (EMIC) waves. Mirror waves are associated with [beta][sub p] > 5 and T[sub [perpendicular]p]/T[sub [parallel]p] of 1.5 whereas EMIC waves occur for [beta][sub p] [le] 1 and T[sub [perpendicular]p]/T[sub [parallel]p] = 2.5 [minus]- 5 (the subscript p denotes quantities evaluated for protons). EMIC waves also occur for higher field strength and lower plasma densities than mirror waves, indicative of EMIC wave occurrencemore » in the plasma depletion layer (PDL). The increased T[sub [perpendicular]p]/T[sub [parallel]p] during EMIC waves relative to periods of mirror waves is due to a decrease in T[sub [parallel]p] suggesting that the EMIC wave region has suffered a loss of particles in the parallel direction. A compilation of the temporal sequence of spectral structures shows that EMIC waves occur next to the magnetopause while mirror waves occur outside the region of EMIC waves. We conclude that there is a close relationship between EMIC waves in the sheath and the PDL. 31 refs., 7 figs., 4 tabs.« less

Authors:
 [1];  [2]
  1. Johns Hopkins Univ., Laurel, MD (United States)
  2. Lockheed Palo Alto Research Lab., CA (United States)
Publication Date:
OSTI Identifier:
6787746
Resource Type:
Journal Article
Journal Name:
Journal of Geophysical Research; (United States)
Additional Journal Information:
Journal Volume: 98:A2; Journal ID: ISSN 0148-0227
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; MAGNETOSHEATH; PULSATIONS; SOLAR WIND; SHOCK WAVES; ANISOTROPY; DENSITY; DISTRIBUTION; ELECTRONS; FLUCTUATIONS; GYROFREQUENCY; HELIUM IONS; HYDROGEN IONS 1 PLUS; HZ RANGE; INTERPLANETARY MAGNETIC FIELDS; MAGNETOPAUSE; MILLI HZ RANGE; PARTICLES; PLASMA; PROTONS; BARYONS; CATIONS; CHARGED PARTICLES; ELEMENTARY PARTICLES; FERMIONS; FREQUENCY RANGE; HADRONS; HYDROGEN IONS; IONS; LEPTONS; MAGNETIC FIELDS; NUCLEONS; PHYSICAL PROPERTIES; SOLAR ACTIVITY; VARIATIONS; 661320* - Auroral, Ionospheric, & Magnetospheric Phenomena- (1992-)

Citation Formats

Anderson, B J, and Fuselier, S A. Magnetic pulsations from 0. 1 to 4. 0 Hz and associated plasma properties in the earth's subsolar magnetosheath and plasma depletion layer. United States: N. p., 1993. Web. doi:10.1029/92JA02197.
Anderson, B J, & Fuselier, S A. Magnetic pulsations from 0. 1 to 4. 0 Hz and associated plasma properties in the earth's subsolar magnetosheath and plasma depletion layer. United States. https://doi.org/10.1029/92JA02197
Anderson, B J, and Fuselier, S A. 1993. "Magnetic pulsations from 0. 1 to 4. 0 Hz and associated plasma properties in the earth's subsolar magnetosheath and plasma depletion layer". United States. https://doi.org/10.1029/92JA02197.
@article{osti_6787746,
title = {Magnetic pulsations from 0. 1 to 4. 0 Hz and associated plasma properties in the earth's subsolar magnetosheath and plasma depletion layer},
author = {Anderson, B J and Fuselier, S A},
abstractNote = {Dynamic spectral analysis covering frequencies 0.1 to 4.0 Hz has been applied to analyze Active Magnetospheric Particle Tracer Explorers CCE magnetic field data during periods of magnetospheric compressions when the spacecraft sampled the magnetosheath. Ion (H[sup +], He[sub 2+]) and electron data are used to identify regions, to monitor the upstream shock geometry, and to evaluate moments of the proton distribution. For quasi-perpendicular shock conditions, two distinctive band limited spectral types are found to characterize the majority of magnetosheath observations: (1) purely compressional fluctuations with F < 0.2 F[sub H][sup +] which are attributed to mirror waves (F and F[sub H][sup +] denote the wave frequency and proton gyrofrequency, respectively); and (2) 0.25-1.0 F[sub H][sup +] frequency purely transverse fluctuations that are often left hand polarized from 0.5-1.0 F[sub H][sup +] and are attributed to electromagnetic ion cyclotron (EMIC) waves. Mirror waves are associated with [beta][sub p] > 5 and T[sub [perpendicular]p]/T[sub [parallel]p] of 1.5 whereas EMIC waves occur for [beta][sub p] [le] 1 and T[sub [perpendicular]p]/T[sub [parallel]p] = 2.5 [minus]- 5 (the subscript p denotes quantities evaluated for protons). EMIC waves also occur for higher field strength and lower plasma densities than mirror waves, indicative of EMIC wave occurrence in the plasma depletion layer (PDL). The increased T[sub [perpendicular]p]/T[sub [parallel]p] during EMIC waves relative to periods of mirror waves is due to a decrease in T[sub [parallel]p] suggesting that the EMIC wave region has suffered a loss of particles in the parallel direction. A compilation of the temporal sequence of spectral structures shows that EMIC waves occur next to the magnetopause while mirror waves occur outside the region of EMIC waves. We conclude that there is a close relationship between EMIC waves in the sheath and the PDL. 31 refs., 7 figs., 4 tabs.},
doi = {10.1029/92JA02197},
url = {https://www.osti.gov/biblio/6787746}, journal = {Journal of Geophysical Research; (United States)},
issn = {0148-0227},
number = ,
volume = 98:A2,
place = {United States},
year = {Mon Feb 01 00:00:00 EST 1993},
month = {Mon Feb 01 00:00:00 EST 1993}
}