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| Titel |
Evaluation of the Surface Energy Balance System (SEBS) applied to ASTER imagery with flux-measurements at the SPARC 2004 site (Barrax, Spain) |
| VerfasserIn |
J. Kwast, W. Timmermans, A. Gieske, Z. Su, A. Olioso, L. Jia, J. Elbers, D. Karssenberg, S. Jong |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1027-5606
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| Digitales Dokument |
URL |
| Erschienen |
In: Hydrology and Earth System Sciences ; 13, no. 7 ; Nr. 13, no. 7 (2009-07-29), S.1337-1347 |
| Datensatznummer |
250011950
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| Publikation (Nr.) |
 copernicus.org/hess-13-1337-2009.pdf |
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| Zusammenfassung |
| Accurate quantification of the amount and spatial variation of evapotranspiration
is important in a wide range of disciplines. Remote sensing based surface energy
balance models have been developed to estimate turbulent surface energy
fluxes at different scales. The objective of this study is to evaluate the
Surface Energy Balance System (SEBS) model on a landscape scale, using
tower-based flux measurements at different land cover units during an
overpass of the ASTER sensor over the SPARC 2004 experimental site in
Barrax (Spain). A sensitivity analysis has been performed in order to
investigate to which variable the sensible heat flux is most sensitive.
Taking into account their estimation errors, the aerodynamic parameters
(hc, z0M and d0) can cause large deviations in the modelling
of sensible heat flux. The effect of replacement of empirical derivation
of these aerodynamic parameters in the model by field estimates or literature
values is investigated by testing two scenarios: the Empirical Scenario in
which empirical equations are used to derive aerodynamic parameters and the
Field Scenario in which values from field measurements or literature are
used to replace the empirical calculations of the Empirical Scenario. In
the case of a homogeneous land cover in the footprints of the measurements,
the Field Scenario only resulted in a small improvement, compared to the
Empirical Scenario. The Field Scenario can even worsen the result in the
case of heterogeneous footprints, by creating sharp borders related to the
land cover map. In both scenarios modelled fluxes correspond better with
flux measurements over uniform land cover compared to cases where different
land covers are mixed in the measurement footprint. Furthermore SEBS
underestimates sensible heat flux especially over dry and sparsely vegetated
areas, which is common in single-source models. |
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