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| Titel |
Particular uncertainties encountered in using a pre-packaged SEBS model to derive evapotranspiration in a heterogeneous study area in South Africa |
| VerfasserIn |
L. A. Gibson, Z. Münch, J. Engelbrecht |
| 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 ; 15, no. 1 ; Nr. 15, no. 1 (2011-01-25), S.295-310 |
| Datensatznummer |
250012603
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| Publikation (Nr.) |
 copernicus.org/hess-15-295-2011.pdf |
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| Zusammenfassung |
| The focus of this paper is on the pre-packaged version of SEBS in ILWIS and
the sensitivity of SEBS to some parameters over which the user has some
control when using this version of the model, in order to make informed
choices to limit uncertainties. The sensitivities of SEBS to input
parameters are related to daily ET rather than energy flux results since
this is of interest to water managers and other users of the results of the
SEBS model. This paper describes some of the uncertainties introduced by the
sensitivity of the SEBS model to (a) land surface temperature and air
temperature gradient, (b) the choice of fractional vegetation formula, (c)
displacement height and the height at which wind speed is measured, and (d)
study area heterogeneity. It was shown that SEBS is sensitive to land
surface temperature and air temperature gradient and the magnitude of this
sensitivity depended on the land cover and whether or not the wet-limit had
been reached. The choice of fractional vegetation cover formula was shown to
influence the daily ET results by up to 0.7 mm. It was shown that the height
of the vegetation canopy should be considered in relation to the weather
station reference height to avoid the sensible heat flux from becoming
unsolvable due to a negative ln calculation. Finally the study area was
shown to be heterogeneous although the resolution at which fluxes were
calculated did not significantly impact on energy partitioning results. The
differences in the upscaling from evaporative fraction to daily ET at
varying resolutions observed implies that the heterogeneity may play the
biggest role in the upscaling and the influence of albedo on this
calculation should be studied. |
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