Effects of azimuthal asymmetry on ULF waves in the dipole magnetosphere

Journal Article · Mon Jan 01 04:00:00 EST 1990 · Geophysical Research Letters (American Geophysical Union); (USA)

DOI:https://doi.org/10.1029/GL017i001p00053· OSTI ID:6230316

Lee, Donghun; Lysak, R L ^[1]

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1. Univ. of Minnesota, MN (USA)

The properties of the coupling of compressional and transverse ULF waves strongly depend on the azimuthal wavenumber m. The authors investigate these effects in a numerical model of ULF wave propagation in a dipolar magnetosphere. As the azimuthal wave number m becomes larger, the frequencies of the global modes are increased, each coupling location is shifted toward the plasmapause, and the wave energy of global compressional modes in the magnetosphere is confined to a smaller region near the magnetopause. These conclusions are qualitatively consistent with previous analytical and numerical models. It is suggested that the radial dependence of the azimuthal wavelength in the dipole geometry is important to the propagation of compressional waves. This effect is not present in either box or cylindrical models, in which the azimuthal wavelength does not depend on the radial distance, and can be distinguished from effects arising from the inhomogeneity of the Alfven speed. On the other hand, the Alfven shear modes are found to have periods independent of m.

• OSTI ID: 6230316
• Journal Information: Geophysical Research Letters (American Geophysical Union); (USA), Journal Name: Geophysical Research Letters (American Geophysical Union); (USA) Vol. 17:1; ISSN 0094-8276; ISSN GPRLA
• 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
DIPOLES
EARTH ATMOSPHERE
EARTH MAGNETOSPHERE
ELECTROMAGNETIC RADIATION
FLUID MECHANICS
HYDRODYNAMICS
HYDROMAGNETIC WAVES
MAGNETOHYDRODYNAMICS
MAGNETOPAUSE
MATHEMATICAL MODELS
MECHANICS
MULTIPOLES
PLASMAPAUSE
RADIATIONS
SHEAR
ULTRALOW FREQUENCY RADIATION
VARIATIONS
WAVE PROPAGATION