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Dayside ionospheric convection changes in response to long-period interplanetary magnetic field oscillations - Determination of the ionospheric phase velocityGround magnetic field perturbations recorded by the CANOPUS magnetometer network in the 7 to 13 MLT sector are used to examine how reconfigurations of the dayside polar ionospheric flow take place in response to north-south changes of the IMF. During the 6-h interval in question, IMF Bz oscillates between +/- 7 nT with about a 1-h period. Corresponding variations in the ground magnetic disturbance are observed which we infer are due to changes in ionospheric flow. Cross correlation of the data obtained from two ground stations at 73.5 deg magnetic latitude, but separated by about 2 hours in MLT, shows that changes in the flow are initiated in the prenoon sector (about 10 MLT) and then spread outward toward dawn and dusk with a phase speed of about 5 km/s over the longitude range about 8 to 12 MLT, slowing to about 2 km/s outside this range. Cross correlating the data from these ground stations with IMP 8 IMF Bz records produces a MLT variation in the ground response delay relative to the IMF which is compatible with these deduced phase speeds.
Document ID
19930037002
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Saunders, M. A.
(Imperial College of Science, Technology, and Medicine London, United Kingdom)
Freeman, M. P.
(British Antarctic Survey Cambridge, United Kingdom)
Southwood, D. J.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Cowley, S. W.
(Imperial College of Science, Technology, and Medicine London, United Kingdom)
Lockwood, M.
(Rutherford Appleton Lab. Didcot, United Kingdom)
Samson, J. C.
(Alberta Univ. Edmonton, Canada)
Farrugia, C. J.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Hughes, T. J.
(National Research Council of Canada Herzberg Inst. of Astrophysics, Ottawa, United States)
Date Acquired
August 16, 2013
Publication Date
December 1, 1992
Publication Information
Publication: Journal of Geophysical Research
Volume: 97
Issue: A12
ISSN: 0148-0227
Subject Category
Geophysics
Accession Number
93A20999
Distribution Limits
Public
Copyright
Other

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