Resonant geomagnetic field oscillations and Birkeland currents in the morning sector

Journal Article · Fri Apr 01 04:00:00 EST 1988 · Journal of Geophysical Research; (United States)

DOI:https://doi.org/10.1029/JA093iA04p02661· OSTI ID:6095933

Potemra, T A; Zanetti, L J; Bythrow, P F; Erlandson, R E ^[1]; Lundin, R ^[2]; Marklund, G T; Block, L P; Lindqvist, P A ^[3]

---

1. Johns Hopkins Univ., Laurel, MD (United States)
2. Swedish Inst. of Space Physics, Kiruna (Sweden)
3. Royal Inst. of Tech., Stockholm (Sweden)

Magnetic field, electric field, and particle measurements acquired by the Viking satellite and magnetic field measurements acquired by the Active Magnetosphere Particle Tracer Explorers (AMPTE) CCE satellite have been used to study the relationship between large-scale Birkeland currents and resonant oscillations in the Earth's magnetic field. Region 1, region 2, and northward B{sub Z} (NBZ) Birkeland currents were identified with the data acquired by the Viking magnetic field instrument. Magnetic field oscillations, present in each of the 10 consecutive Viking passes studied here, have periods between 1 min. and 6 min. and amplitudes from 5 nT to 60 nT. These oscillations extend from lower L shells where they correlate with the CCCE observations up to at least the interface between the region 1 and region 2 Birkeland current system. The Viking particle observations confirm that the region 1/region 2 interface maps closely to the interface between the low-latitude boundary layer (LLBL) and the central plasma sheet (CPS). Electric and magnetic field variations are closely correlated in the region 1 Birkeland current. In the region 2 system of Birkeland currents, the northward electric and eastward magnetic field components show the same resonance oscillations with the electric field variations leading the magnetic field by approximately 90{degree}. There is evidence that the amplitudes of the oscillations observed by Viking are correlated with interplanetary magnetic field (IMF) cone angle. In one case, the energy-time dispersion signature of temporal magnetosheath plasma injection into the low-latitude boundary layer was associated with the resonant oscillations. These relationships and the presence of the resonant oscillations on field lines up to the region 1/region 2 (LLBL/CPS) interface lead us to conclude that there are several features in the solar wind and the direction of the IMF that can initiate magnetospheric pulsations.

• OSTI ID: 6095933
• Journal Information: Journal of Geophysical Research; (United States), Journal Name: Journal of Geophysical Research; (United States) Vol. 93; ISSN JGREA; ISSN 0148-0227
• Country of Publication: United States
• Language: English

Related Subjects

661320* -- Auroral
Ionospheric
& Magnetospheric Phenomena-- (1992-)
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
AMPLITUDES
AURORAL ZONES
BOUNDARY LAYERS
CORRELATIONS
CURRENTS
EARTH ATMOSPHERE
EARTH MAGNETOSPHERE
ELECTRIC CURRENTS
ELECTRIC FIELDS
GEOMAGNETIC FIELD
INTERPLANETARY MAGNETIC FIELDS
LAYERS
MAGNETIC FIELDS
OSCILLATIONS
PLASMA SHEET
POLAR CUSP
SATELLITES
SOLAR ACTIVITY
SOLAR WIND
VARIATIONS