ULF waves in the low-latitude boundary layer and their relationship to magnetospheric pulsations: A multisatellite observation

Journal Article · Sat Jun 01 04:00:00 EDT 1991 · Journal of Geophysical Research; (United States)

DOI:https://doi.org/10.1029/91JA00612· OSTI ID:5222468

Takahashi, Kazue; Sibeck, D G; Newell, P T ^[1]; Spence, H E ^[2]

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1. Johns Hopkins Univ., Laurel, MD (USA)
2. Aerospace Corp., El Segundo, CA (USA)

On April 30 (day 120), 1985, the magnetosphere was compressed at 0923 UT and the subsolar magnetopause remained near 7 R{sub E} feocentric for {approximately} 2 hours, during which the four spacecraft Spacecraft Charging At High Altitude (SCATHA), GOES 5, GOES 6, and Active Magnetospheric Particle Tracer Explorers (AMPTE) CCE were all in the magnetosphere on the morning side. SCATHA was in the low-latitude boundary layer (LLBL) in the second half of this period. The interplanetary magnetic field was inferred to be northward from the characteristics of precipitating partcile fluxes as observed by the low-altitude satellite Defense Meteorological Satellite Program (DMSP) F7 and also from absence of substorms. The authors used magnetic field and particle data from this unique interval to study ULF waves in the LLBL and their relationship to magnetic pulsations in the magnetosphere. The LLBL was identified from the properties of particles, including bidirectional field-aligned electron beams at {approximately} 200 eV. In the boundary layer the magnetic field exhibited both a 5-10 min irregular compressional oscillation and a broadband ({Delta}f/f {approximately} 1) primarily transverse oscillations with a mean period of {approximately} 50 s and a left-hand sense of polarization about the mean field. The former can be observed by other satellites and is likely due to pressure variations in the solar wind, while the latter is likely due to a Kelvin-Helmholtz (K.-H.) instability occurring in the LLBL or on the magnetopause. Also, a strongly transverse {approximately} 3-s oscillation was observed in the LLBL. The magnetospheric pulsations, which exhibited position dependent frequencies, may be explained in terms of field line resonance with a broadband source wave, that is, either the pressure-induced compressional wave or the K.-H. wave generated in or near the boundary.

• OSTI ID: 5222468
• Journal Information: Journal of Geophysical Research; (United States), Journal Name: Journal of Geophysical Research; (United States) Vol. 96:A6; ISSN 0148-0227; ISSN JGREA
• Country of Publication: United States
• Language: English

Related Subjects

640201* -- Atmospheric Physics-- Auroral
Ionospheric
& Magetospheric Phenomena
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ALFVEN WAVES
BEAMS
BOUNDARY LAYERS
CHARGED-PARTICLE PRECIPITATION
COMPRESSION
EARTH ATMOSPHERE
EARTH MAGNETOSPHERE
ELECTRON BEAMS
ENERGY TRANSFER
HELMHOLTZ INSTABILITY
HYDROMAGNETIC WAVES
INSTABILITY
INTERPLANETARY MAGNETIC FIELDS
LAYERS
LEPTON BEAMS
MAGNETIC FIELDS
MAGNETOPAUSE
MASS TRANSFER
MOMENTUM TRANSFER
PARTICLE BEAMS
PLASMA INSTABILITY
PLASMA MACROINSTABILITIES
PLASMA WAVES
SATELLITES