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Geomagnetic pulsations observed simultaneously on three geostationary satellitesSimultaneous observations of magnetic pulsations have been made by three geostationary satellites carrying similar magnetometers and acting as an azimuthal array. Autospectral and cross-spectral analysis yields coherence and phase differences between the pulsations at the satellite positions. The majority of the data fit the Kelvin-Helmholtz generation mechanism. The azimuthal wave number changes sign near noon and corresponds to propagation away from noon. Usually, the wave number is less than 10 deg per degree of longitude. Later in the afternoon, however, strong pulsations are observed with low coherence, implying large wave numbers. This suggests an instability driven by a gradient in the intensity of energetic protons, which may be expected at this local time. The data also suggest that some of the observed phase difference between the azimuthal components is due to small separations in magnetic shell, whereas this is not the case for the radial components. This implies a localized field-line resonance.
Document ID
19780046159
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Hughes, W. J.
(California Univ. Los Angeles, CA, United States)
Mcpherron, R. L.
(California, University Los Angeles, Calif., United States)
Barfield, J. N.
(NOAA, Space Environment Laboratory, Boulder Colo., United States)
Date Acquired
August 9, 2013
Publication Date
March 1, 1978
Publication Information
Publication: Journal of Geophysical Research
Volume: 83
Subject Category
Geophysics
Accession Number
78A30068
Funding Number(s)
CONTRACT_GRANT: NAS5-11674
Distribution Limits
Public
Copyright
Other

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