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| Titel |
Accurate estimation of third-order moments from turbulence measurements |
| VerfasserIn |
J. J. Podesta, M. A. Forman, C. W. Smith, D. C. Elton, Y. Malécot, Y. Gagne |
| 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 ; 16, no. 1 ; Nr. 16, no. 1 (2009-02-17), S.99-110 |
| Datensatznummer |
250013091
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| Publikation (Nr.) |
 copernicus.org/npg-16-99-2009.pdf |
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| Zusammenfassung |
| Politano and Pouquet's law, a generalization of Kolmogorov's four-fifths law
to incompressible MHD, makes it possible to measure the energy cascade rate in
incompressible MHD turbulence by means of third-order moments. In hydrodynamics,
accurate measurement of third-order moments requires large amounts of data because
the probability distributions of velocity-differences are nearly symmetric and the
third-order moments are relatively small. Measurements of the energy cascade
rate in solar wind turbulence have recently been performed for the first time, but without
careful consideration of the accuracy or statistical uncertainty of the required
third-order moments. This paper investigates the statistical convergence
of third-order moments as a function of the sample size N.
It is shown that the accuracy of the third-moment <(δ v||)3>
depends on the number of correlation lengths spanned by the data set and a method of
estimating the statistical uncertainty of the third-moment is developed.
The technique is illustrated using both wind tunnel data and solar wind data. |
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