Distribution of ULF energy (f < 80 mHz) in the inner magnetosphere: A statistical analysis of AMPTE CCE magnetic field data
- Johns Hopkins Univ., Laurel, MD (United States)
The distribution of ULF energy (frequency < 80 mHz) in the inner magnetosphere (L = 2.5-6.5) has been studied using magnetic field measurements made with the Active Magnetospheric Particle Tracers Explorers Charge Composition Explorer (AMPTE CCE) spacecraft during its whole mission of over 4 years. The magnetic field time series was split into consecutive 10-min segments and subjected to fast Fourier transform (FFT), and the spectral data were achieved along with the Kp index and the satellite location. This data base was then used to examine the spatial distribution of ULF energy. Overall, the oscillation energy is localized to the dayside except for compressional oscillations associated with substorms. From the spatial distributions of wave power and spectral structures the authors identify several pulsation types, including multiharmonic toroidal oscillations; equatorial compressional Pc 3 oscillations; second harmonic poloidal oscillations; and nightside compressional oscillations; equatorial compressional Pc 3 oscillations; second harmonic poloidal oscillations; and nightside compressional oscillations. The toroidal oscillations are observable even in the plasmasphere, and using their frequencies they can determine the statistical radial profile of the plasma mass density and Alfven velocity. They find a clear signature of the plasmapause in the profiles of these average parameters. Of particular interest among the other oscillation types are the equatorial compressional Pc 3 oscillations that have an average spectral peak around 30 mHz and are present in the prenoon sector and from L{approximately}3 to {approximately}5. The oscillations are similar to the compressional Pc3 previously observed at and near geostationary orbit and might represent magnetohydrodynamic waves propagating from the parallel portion of the bow shock.
- OSTI ID:
- 7158405
- Journal Information:
- Journal of Geophysical Research; (United States), Vol. 97:A7; ISSN 0148-0227
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
GENERAL PHYSICS
EARTH MAGNETOSPHERE
HYDROMAGNETIC WAVES
COLLISIONLESS PLASMA
EXPLORER SATELLITES
INTERACTIONS
PLASMA DENSITY
PLASMASPHERE
SHOCK WAVES
SOLAR WIND
SPATIAL DISTRIBUTION
TIME-SERIES ANALYSIS
DISTRIBUTION
EARTH ATMOSPHERE
MATHEMATICS
PLASMA
SATELLITES
SOLAR ACTIVITY
661320* - Auroral
Ionospheric
& Magnetospheric Phenomena- (1992-)