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| Titel |
Non-Gaussian statistics in space plasma turbulence: fractal properties and pitfalls |
| VerfasserIn |
T. Wit, V. V. Krasnosel'skikh |
| 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 ; 3, no. 4 ; Nr. 3, no. 4, S.262-273 |
| Datensatznummer |
250001124
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| Publikation (Nr.) |
 copernicus.org/npg-3-262-1996.pdf |
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| Zusammenfassung |
| Statistical properties of
collisionless plasmas in
the vicinity of the Earth's bow shock are
investigated with
the aim to characterize the intermittent behaviour
of non-
magnetohydrodynamic turbulence. The structure
functions of
the fluctuating magnetic field reveal an increasing
departure
from Gaussianity at small scales, which is similar
to that
observed in solar wind turbulence and is surprisingly
little
affected by the abrupt shock transition. While these
results
may be the signature of a multifractal process, a
deeper
inspection reveals caveats in such an interpretation.
Several
effects, including the anisotropy of the
wavefield, the
violation of the Taylor hypothesis and the
occasional
occurrence of coherent wave packets, strongly
affect the
higher order statistical properties. Most of the
small
differences observed between the up- and downstream
sides of
the shock can be ascribed to the occurrence of
discrete
whistler wavetrains, while the wavefield itself is
much less
intermittent. It is also shown how the finite length
of the
records prohibits a reliable estimation of structure
functions
beyond the fourth order. These results
preclude an
unambiguous identification of underlying
models for
intermittency. |
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