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| Titel |
Anisotropic scaling of remotely sensed drainage basins: the differential anisotropy scaling technique |
| VerfasserIn |
A. Beaulieu, H. Gaonac'h, S. Lovejoy |
| 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 ; 14, no. 4 ; Nr. 14, no. 4 (2007-07-06), S.337-350 |
| Datensatznummer |
250012234
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| Publikation (Nr.) |
 copernicus.org/npg-14-337-2007.pdf |
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| Zusammenfassung |
| We investigate the statistical properties of dendritic drainage areas from
diverse geological environments (Deception Canyon, Utah and the Loess
Plateau, China) using narrow band visible ASTER satellite images. We show
that from 240 m to 7680 m, the isotropic (angle integrated) energy spectra
E(k) of all the fields closely follow a power law form:
E(k)∝k−β
where k is a wave number and β a scale invariant exponent. In spite of this
good isotropic scaling, images with very similar β's and similar isotropic
multifractal exponents have distinct textures; we suggest that the
differences are primarily due to anisotropy, which is nevertheless scaling.
We develop the new "Differential Anisotropy Scaling" technique to characterize this scale-by-scale
(differential) anisotropy and we test it on simulated anisotropic scaling fields.
The method gives useful characterizations of the scale by scale anisotropy
irrespective of whether or not the analyzed field is scaling. When the
anisotropy is not too strong, the parameters can be interpreted as scale
invariant anisotropy exponents. Viewed as a method of estimating these
exponents, it has the advantage of relying on two linear regressions rather
than on complex higher dimensional nonlinear ones. When applied to dendritic
drainage basins we find that they have distinct anisotropies characterized
by differential anisotropy stretching and rotation parameters as well as
by a distinct absolute anisotropy at the reference scale of 960 m. Our
new method allows us to statistically distinguish, not only between two
geologically different drainage basins (the China Loess Plateau and Utah
Deception Canyon), but also between different regions of the same China
drainage system. |
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