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Polar Spacecraft Observations of the Turbulent Outer Cusp/Magnetopause Boundary Layer of EarthThe orbit of the Polar spacecraft has been ideally suited for studying the turbulent region of the cusp that is located near or just outside the magnetopause current sheet at 7-9 R(sub E). The wave data obtained in this region show that electromagnetic turbulence is dominant in the frequency range 1-10 Hz. The waves responsible for this turbulence usually propagate perpendicular to the local magnetic field and have an index of refraction that generally falls between the estimated cold plasma theoretical values of the electromagnetic lower hybrid and whistler modes and may be composed of both modes in concert with kinetic Alfven waves and/or fast magnetosonic waves. Fourier spectra of the higher frequency wave data also show the electromagnetic turbulence at frequencies up to and near the electron cyclotron frequency. This higher frequency electromagnetic turbulence is most likely associated with whistler mode waves. The lower hybrid drift and current gradient instabilities are suggested as possible mechanisms for producing the turbulence. The plasma and field environment of this turbulent region is examined and found to be extremely complex. Some of the wave activity is associated with processes occurring locally, such as changes in the DC magnetic field, while others are associated with solar wind and interplanetary magnetic field changes.
Document ID
Document Type
Reprint (Version printed in journal)
Pickett, J. S. (Iowa Univ. Iowa City, IA United States)
Menietti, J. D. (Iowa Univ. Iowa City, IA United States)
Dowell, J. H. (Iowa Univ. Iowa City, IA United States)
Gurnett, D. A. (Iowa Univ. Iowa City, IA United States)
Scudder, J. D. (Iowa Univ. Iowa City, IA United States)
Date Acquired
August 20, 2013
Publication Date
January 1, 1999
Publication Information
Publication: Nonlinear Processes in Geophysics
Volume: 6
Subject Category
Funding Number(s)
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