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| Titel |
Analysis of the geomagnetic activity of the Dst index and self-affine fractals using wavelet transforms |
| VerfasserIn |
H. L. Wei, S. A. Billings, M. Balikhin |
| 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 ; 11, no. 3 ; Nr. 11, no. 3 (2004-06-18), S.303-312 |
| Datensatznummer |
250009235
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| Publikation (Nr.) |
 copernicus.org/npg-11-303-2004.pdf |
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| Zusammenfassung |
| The geomagnetic activity of the Dst index is analyzed using wavelet transforms
and it is shown that the Dst index possesses properties associated with
self-affine fractals. For example, the power spectral density obeys a
power-law dependence on frequency, and therefore the Dst index can be viewed as
a self-affine fractal dynamic process. In fact, the behaviour of the Dst index,
with a Hurst exponent H≈0.5 (power-law exponent β≈2) at
high frequency, is similar to that of Brownian motion. Therefore, the
dynamical invariants of the Dst index may be described by a potential Brownian
motion model. Characterization of the geomagnetic activity has been studied
by analysing the geomagnetic field using a wavelet covariance technique. The
wavelet covariance exponent provides a direct effective measure of the
strength of persistence of the Dst index. One of the advantages of wavelet
analysis is that many inherent problems encountered in Fourier transform
methods, such as windowing and detrending, are not necessary. |
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