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| Titel |
The SPARSE model for the prediction of water stress and evapotranspiration components from thermal infra-red data and its evaluation over irrigated and rainfed wheat |
| VerfasserIn |
G. Boulet, B. Mougenot, J.-P. Lhomme, P. Fanise, Z. Lili-Chabaane, A. Olioso, M. Bahir, V. Rivalland, L. Jarlan, O. Merlin, B. Coudert, S. Er-Raki, J.-P. Lagouarde |
| 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 ; 19, no. 11 ; Nr. 19, no. 11 (2015-11-25), S.4653-4672 |
| Datensatznummer |
250120856
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| Publikation (Nr.) |
 copernicus.org/hess-19-4653-2015.pdf |
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| Zusammenfassung |
| Evapotranspiration is an important component of the water cycle, especially
in semi-arid lands. A way to quantify the spatial distribution of
evapotranspiration and water stress from remote-sensing data is to exploit
the available surface temperature as a signature of the surface energy
balance. Remotely sensed energy balance models enable one to estimate stress
levels and, in turn, the water status of continental surfaces. Dual-source
models are particularly useful since they allow derivation of a rough
estimate of the water stress of the vegetation instead of that of a
soil–vegetation composite. They either assume that the soil and the
vegetation interact almost independently with the atmosphere (patch approach
corresponding to a parallel resistance scheme) or are tightly coupled (layer
approach corresponding to a series resistance scheme). The water status of
both sources is solved simultaneously from a single surface temperature
observation based on a realistic underlying assumption which states that, in
most cases, the vegetation is unstressed, and that if the vegetation is
stressed, evaporation is negligible. In the latter case, if the vegetation
stress is not properly accounted for, the resulting evaporation will decrease
to unrealistic levels (negative fluxes) in order to maintain the same total
surface temperature. This work assesses the retrieval performances of total
and component evapotranspiration as well as surface and plant water stress
levels by (1) proposing a new dual-source model named Soil Plant Atmosphere
and Remote Sensing Evapotranspiration (SPARSE) in two versions (parallel and
series resistance networks) based on the TSEB (Two-Source Energy Balance model,
Norman et al., 1995) model rationale as well as state-of-the-art formulations of
turbulent and radiative exchange, (2) challenging the limits of the
underlying hypothesis for those two versions through a synthetic retrieval
test and (3) testing the water stress retrievals (vegetation water stress and
moisture-limited soil evaporation) against in situ data over contrasted test
sites (irrigated and rainfed wheat). We demonstrated with those two data sets
that the SPARSE series model is more robust to component stress retrieval for
this cover type, that its performance increases by using bounding
relationships based on potential conditions (root mean square error lowered
by up to 11 W m−2 from values of the order of 50–80 W m−2),
and that soil evaporation retrieval is generally consistent with an
independent estimate from observed soil moisture evolution. |
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