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| Titel |
Polar spacecraft observations of the turbulent outer cusp/magnetopause boundary layer of Earth |
| VerfasserIn |
J. S. Pickett, J. D. Menietti, J. H. Dowell, D. A. Gurnett, J. D. Scudder |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1023-5809
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| Digitales Dokument |
URL |
| Erschienen |
In: Nonlinear Processes in Geophysics ; 6, no. 3/4 ; Nr. 6, no. 3/4, S.195-204 |
| Datensatznummer |
250003224
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| Publikation (Nr.) |
 copernicus.org/npg-6-195-1999.pdf |
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| Zusammenfassung |
| The 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 RE. 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 Alfvén 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. |
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