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| Titel |
Multifractal scaling of the kinetic energy flux in solar wind turbulence |
| VerfasserIn |
E. Marsch, C.-Y. Tu, H. Rosenbauer |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
0992-7689
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| Digitales Dokument |
URL |
| Erschienen |
In: Annales Geophysicae ; 14, no. 3 ; Nr. 14, no. 3, S.259-269 |
| Datensatznummer |
250012205
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| Publikation (Nr.) |
 copernicus.org/angeo-14-259-1996.pdf |
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| Zusammenfassung |
| The geometrical and scaling properties of the
energy flux of the turbulent kinetic energy in the solar wind have been studied.
Using present experimental technology in solar wind measurements we cannot
directly measure the real volumetric dissipation rate, ε(t),
but are constrained to represent it by its surrogate the energy flux near the
dissipation range at the proton gyro scale. There is evidence for the
multifractal nature of the so defined dissipation field ε(t),
a result derived from the scaling exponents of its statistical moments. The
generalized dimension Dq has been determined and reveals that
the dissipation field has a multifractal structure, which is not compatible with
a scale-invariant cascade. The related multifractal spectrum α
has been estimated for the first time for MHD turbulence in the solar wind. Its
features resemble those obtained for turbulent fluids and other nonlinear
multifractal systems. The generalized dimension Dq can for
turbulence in high-speed streams be fitted well by the functional dependence of
the p-model with a comparatively large parameter p1=0.87,
indicating a strongly intermittent multifractal energy cascade. The experimental
value for Dp/3 used in the scaling exponent s(p)
of the velocity structure function gives an exponent that can describe some of
the observations. The scaling exponent μ of the autocorrelation
function of ε (t) has also been directly evaluated, being
0.37. Finally, the mean dissipation rate was determined, which could be used in
solar wind heating models. |
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