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Spatial and temporal behavior of ULF pulsations observed by the Goose Bay HF radarTechniques which allow the instantaneous amplitude and phase to be determined as functions of geomagnetic lattitude, longitude, and time are employed to carry out a detailed analysis of HF radar data of a ULF pulsation event in the postmidnight sector on January 11, 1989. Field line resonances with several different frequencies occur simultaneously at different latitudes. These can be associated with cavity mode frequencies of 1.3 mHz, 1.9 mHz, 2.7 mGz, and 3.3 mHz. These frequencies are constant to better than 10 percent over a local time period of nearly 4 hr. The field-aligned currents driven by the resonances can be as large as 5 micro-A/sq m at ionospheric heights. The data support a picture of modes driven by solar wind impulses.
Document ID
19920068567
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Walker, A. D. M.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Ruohoniemi, J. M.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Baker, K. B.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Greenwald, R. A.
(Johns Hopkins University Laurel, MD, United States)
Samson, J. C.
(Alberta, University Edmonton, Canada)
Date Acquired
August 15, 2013
Publication Date
August 1, 1992
Publication Information
Publication: Journal of Geophysical Research
Volume: 97
Issue: A8 A
ISSN: 0148-0227
Subject Category
Geophysics
Accession Number
92A51191
Funding Number(s)
CONTRACT_GRANT: NAG5-1099
CONTRACT_GRANT: NSF ATM-90-03860
Distribution Limits
Public
Copyright
Other

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