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Titel |
Empirical study of multifractal phase transitions in atmospheric turbulence |
VerfasserIn |
F. Schmitt, D. Schertzer, S. Lovejoy, Y. Brunet |
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 ; 1, no. 2/3 ; Nr. 1, no. 2/3, S.95-104 |
Datensatznummer |
250000002
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Publikation (Nr.) |
copernicus.org/npg-1-95-1994.pdf |
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Zusammenfassung |
We study atmospheric wind turbulence in the framework of
universal multifractals, using several medium resolution (10 Hz) time series. We cut these
original time series into 704 scale invariant realizations. We then compute the moment
scaling exponent of the energy flux K(q) for 4 and 704 realizations, in order to study
qualitative difference between strong and weak events associated with multifractal phase
transitions. We detect a first order multifractal phase transition of the energy flux at
statistical moment of order qD ≈ 2.4 ± 0.2: this means that when the number of
realizations increases, moments order q ≥; qD diverge. These results are confirmed by the
study of probability distributions, and wind structure functions. A consequence of these
findings is that it is no use to compare different cascade models in turbulence by using
the high order wind structure functions, because a linear part will always be encountered
for high enough order moments. Another important implication for multifractal studies of
turbulence is that the asymptotic slope of the scaling moment function is purely a
function of sample size and diverges with it; it implies the same for D∞, which has often
be considered as finite. |
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