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| Titel |
Modelling sub-grid wetland in the ORCHIDEE global land surface model: evaluation against river discharges and remotely sensed data |
| VerfasserIn |
B. Ringeval, B. Decharme, S. L. Piao, P. Ciais, F. Papa, N. Noblet-Ducoudré, C. Prigent, P. Friedlingstein, I. Gouttevin, C. Koven, A. Ducharne |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1991-959X
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| Digitales Dokument |
URL |
| Erschienen |
In: Geoscientific Model Development ; 5, no. 4 ; Nr. 5, no. 4 (2012-07-17), S.941-962 |
| Datensatznummer |
250002765
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| Publikation (Nr.) |
 copernicus.org/gmd-5-941-2012.pdf |
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| Zusammenfassung |
| The quality of the global hydrological simulations performed by land surface
models (LSMs) strongly depends on processes that occur at unresolved spatial
scales. Approaches such as TOPMODEL have been developed, which allow soil
moisture redistribution within each grid-cell, based upon sub-grid scale
topography. Moreover, the coupling between TOPMODEL and a LSM appears as a
potential way to simulate wetland extent dynamic and its sensitivity to
climate, a recently identified research problem for biogeochemical
modelling, including methane emissions. Global evaluation of the
coupling between TOPMODEL and an LSM is difficult, and prior attempts have
been indirect, based on the evaluation of the simulated river flow. This
study presents a new way to evaluate this coupling, within the ORCHIDEE LSM,
using remote sensing data of inundated areas. Because of differences in
nature between the satellite derived information – inundation extent – and
the variable diagnosed by TOPMODEL/ORCHIDEE – area at maximum soil water
content, the evaluation focuses on the spatial distribution of these two
quantities as well as on their temporal variation. Despite some difficulties
in exactly matching observed localized inundated events, we obtain a rather
good agreement in the distribution of these two quantities at a global
scale. Floodplains are not accounted for in the model, and this is a major
limitation. The difficulty of reproducing the year-to-year variability of
the observed inundated area (for instance, the decreasing trend by the end
of 90s) is also underlined. Classical indirect evaluation based on
comparison between simulated and observed river flow is also performed and
underlines difficulties to simulate river flow after coupling with TOPMODEL.
The relationship between inundation and river flow at the basin scale in the
model is analyzed, using both methods (evaluation against remote sensing
data and river flow). Finally, we discuss the potential of the TOPMODEL/LSM
coupling to simulate wetland areas. A major limitation of the coupling for
this purpose is linked to its ability to simulate a global wetland coverage
consistent with the commonly used datasets. However, it seems to be a good
opportunity to account for the wetland areas sensitivity to the climate and
thus to simulate its temporal variability. |
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