Theory of auroral zone PiB pulsation spectra

Journal Article · Wed Jun 01 00:00:00 EDT 1988 · Journal of Geophysical Research; (United States)

DOI:https://doi.org/10.1029/JA093iA06p05942· OSTI ID:5256349

Lysak, R L ^[1]

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1. Univ. of Minnesota, Minneapolis (USA)

Changes in the auroral zone current system are often accompanied by magnetic pulsations with periods of about 1 s. These so-called bursts of irregular pulsations (PiB) have been observed both on ground magnetograms and with in situ satellite observations. These pulsations can be understood as excitations of a resonant cavity in the topside ionosphere, where the Alfven speed has a strong gradient due to the exponential decrease of density above the ionosphere. These waves have a frequency which scales as the ratio of the Alfven speed at the ionosphere divided by the ionospheric scale height. For a pure exponential Alfven speed profile, the mode frequencies are related to zeros of the zeroth-order Bessel function. For other profiles of the density, and therefore Alfven speed, the frequencies are not exactly given by the simple theory, but the frequency and mode structure are similar provided the Alfven speed sharply increases above the ionosphere.

• OSTI ID: 5256349
• Journal Information: Journal of Geophysical Research; (United States), Vol. 93:A6; ISSN 0148-0227
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
AURORAL ZONES
HYDROMAGNETIC WAVES
IONOSPHERE
MATHEMATICAL MODELS
ANALYTICAL SOLUTION
BESSEL FUNCTIONS
ELECTRIC CURRENTS
MAGNETIC RECONNECTION
PLASMA DENSITY
REFLECTION
TRAPPING
WAVE PROPAGATION
CURRENTS
EARTH ATMOSPHERE
FUNCTIONS
PLANETARY IONOSPHERES
640201* - Atmospheric Physics- Auroral
Ionospheric
& Magetospheric Phenomena