ULF cusp pulsations: Diurnal variations and interplanetary magnetic field correlations with ground-based observations
- Air Force Academy, Colorado Springs, CO (United States)
- Univ. of Alaska, Fairbanks, AK (United States)
- Johns Hopkins Univ., Laurel, MD (United States)
In this paper the authors establish the Pc 5 magnetic pulsation signatures of the cusp and boundary regions for the high-latitude dayside cusp region. These signatures were determined by comparing spectrograms of the magnetic pulsations with optical observations of particle precipitation regions observed at the cusp. The ULF pulsations have a diurnal variation, and a cusp discriminant is proposed using a particular narrow-band feature in the pulsation spectrograms. The statistical distribution of this pattern over a 253-day period resembles the statistical cusp description using particle precipitation data from the Defense Meterological Satellite Program (DMSP). The distribution of the ground-based cusp discriminant is found to peak 1 hour earlier than the DMSP cusp distribution. This offset is due to the interplanetary magnetic field (IMF) being predominantly negative B{sub y} for the period when the data were collected. The authors find the diurnal variations so repeatable that only three main categories have statistically different IMF distributions. The identification of the signatures in the magnetic spectrograms of the boundary regions and central cusp allows the spectrogram to be used as a {open_quotes}time line{close_quotes} that shows when the station passed under different regions of the dayside oval. 36 refs., 11 figs., 1 tab.
- OSTI ID:
- 227160
- Journal Information:
- Journal of Geophysical Research, Vol. 100, Issue A10; Other Information: PBD: 1 Oct 1995
- Country of Publication:
- United States
- Language:
- English
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