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| Titel |
On the scaling characteristics of observed and simulated spatial soil moisture fields |
| VerfasserIn |
M. Gebremichael, R. Rigon, G. Bertoldi, T. M. Over |
| 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 (2009-02-25), S.141-150 |
| Datensatznummer |
250013095
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| Publikation (Nr.) |
 copernicus.org/npg-16-141-2009.pdf |
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| Zusammenfassung |
| By providing continuous high-resolution simulations of soil moisture fields,
distributed hydrologic models could be powerful tools to advance the
scientific community's understanding of the space-time variability and
scaling characteristics of soil moisture fields. However, in order to use
the soil moisture simulations from hydrologic models with confidence, it is
important to understand whether the models are able to represent in a
reliable way the processes regulating soil moisture variability. In this
study, a comparison of the scaling characteristics of spatial soil moisture
fields derived from a set of microwave radiometer observations from the
Southern Great Plains 1997 experiment and corresponding simulations using
the distributed hydrologic model GEOtop is performed through the use of
generalized variograms. Microwave observations and model simulations are in
agreement with respect to suggesting the existence of a scale-invariance
property in the variograms of spatial soil moisture fields, and indicating
that the scaling characteristics vary with changes in the spatial average
soil water content. However, observations and simulations give contradictory
results regarding the relationship between the scaling parameters (i.e.
spatial organization) and average soil water content. The drying process
increased the spatial correlation of the microwave observations at both
short and long separation distances while increasing the rate of decay of
correlation with distance. The effect of drying on the spatial correlation
of the model simulations was more complex, depending on the storm and the
simulation examined, but for the largest storm in the simulation most
similar to the observations, drying increased the long-range correlation but
decreased the short-range. This is an indication that model simulations,
while reproducing correctly the total streamflow at the outlet of the
watershed, may not accurately reproduce the runoff production mechanisms.
Consideration of the scaling characteristics of spatial soil moisture fields
can therefore serve as a more intensive means for validating distributed
hydrologic models, compared to the traditional approach of only comparing
the streamflow hydrographs. |
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