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| Titel |
Testing conceptual and physically based soil hydrology schemes against observations for the Amazon Basin |
| VerfasserIn |
M. Guimberteau, A. Ducharne, P. Ciais, J. P. Boisier, S. Peng, M. De Weirdt, H. Verbeeck |
| 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 ; 7, no. 3 ; Nr. 7, no. 3 (2014-06-06), S.1115-1136 |
| Datensatznummer |
250115632
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| Publikation (Nr.) |
 copernicus.org/gmd-7-1115-2014.pdf |
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| Zusammenfassung |
| This study analyzes the performance of the two soil hydrology schemes of the
land surface model ORCHIDEE in estimating Amazonian hydrology and phenology
for five major sub-basins (Xingu, Tapajós, Madeira, Solimões and Negro),
during the 29-year period 1980–2008. A simple 2-layer scheme with a bucket
topped by an evaporative layer is compared to an 11-layer diffusion scheme.
The soil schemes are coupled with a river routing module and a process model
of plant physiology, phenology and carbon dynamics. The simulated water
budget and vegetation functioning components are compared with several data
sets at sub-basin scale. The use of the 11-layer soil diffusion scheme does
not significantly change the Amazonian water budget simulation when compared
to the 2-layer soil scheme (+3.1 and −3.0% in evapotranspiration and
river discharge, respectively). However, the higher water-holding capacity of
the soil and the physically based representation of runoff and drainage in
the 11-layer soil diffusion scheme result in more dynamic soil water storage
variation and improved simulation of the total terrestrial water storage when
compared to GRACE satellite estimates. The greater soil water storage within
the 11-layer scheme also results in increased dry-season evapotranspiration
(+0.5 mm d−1, +17%) and improves river discharge simulation in
the southeastern sub-basins such as the Xingu. Evapotranspiration over this
sub-basin is sustained during the whole dry season with the 11-layer soil
diffusion scheme, whereas the 2-layer scheme limits it after only 2 dry
months. Lower plant drought stress simulated by the 11-layer soil diffusion
scheme leads to better simulation of the seasonal cycle of photosynthesis
(GPP) when compared to a GPP data-driven model based on eddy covariance and
satellite greenness measurements. A dry-season length between 4 and 7 months
over the entire Amazon Basin is found to be critical in distinguishing
differences in hydrological feedbacks between the soil and the vegetation
cover simulated by the two soil schemes. On average, the multilayer soil
diffusion scheme provides little improvement in simulated hydrology over the
wet tropical Amazonian sub-basins, but a more significant improvement is
found over the drier sub-basins. The use of a multilayer soil diffusion
scheme might become critical for assessments of future hydrological changes,
especially in southern regions of the Amazon Basin where longer dry seasons
and more severe droughts are expected in the next century. |
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