Auroral oval micropulsations at a subauroral zone station. [Amplitudes]
A 5-month sample of geomagnetic micropulsation data from Strawberry Hill, Massachusetts, +54/sup 0/ geomagnetic latitude, is analyzed in octave period bandwidths in the 0.5 to 1024-s period range. Hourly average amplitudes of the horizontal and vertical components are used as measures of the activity. The auroral oval (AO) regime of micropulsations is identified by large H and Z amplitudes combined with small H/Z ratios. It is observed during large nighttime disturbances within a ''micropulsation oval'' whose southern boundary extends 1 or 2/sup 0/ of latitude south of the oval delineated by particle precipitation and is attributed to hydromagnetic waves which propagate in the guided mode from the plasma sheet in the magnetospheric tail. Spatial variations of the source strength in the plasma sheet, which vary with micropulsation period, are reflected in the diurnal variations of the AO amplitudes.
- OSTI ID:
- 7265127
- Journal Information:
- J. Geophys. Res.; (United States), Journal Name: J. Geophys. Res.; (United States) Vol. 81:7; ISSN JGREA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
Ionospheric
& Magetospheric Phenomena
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
AMPLITUDES
AURORAE
BOUNDARY CONDITIONS
DISTRIBUTION
DISTURBANCES
EARTH ATMOSPHERE
GEOMAGNETIC FIELD
MAGNETIC FIELDS
MAGNETOSPHERE
PLASMA SHEET
PULSATIONS
SPATIAL DISTRIBUTION
VARIATIONS
WAVE PROPAGATION