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| Titel |
Impact of climate, vegetation, soil and crop management variables on multi-year ISBA-A-gs simulations of evapotranspiration over a Mediterranean crop site |
| VerfasserIn |
S. Garrigues, A. Olioso, D. Carrer, B. Decharme, J.-C. Calvet, E. Martin, S. Moulin, O. Marloie |
| 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 ; 8, no. 10 ; Nr. 8, no. 10 (2015-10-02), S.3033-3053 |
| Datensatznummer |
250116593
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| Publikation (Nr.) |
 copernicus.org/gmd-8-3033-2015.pdf |
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| Zusammenfassung |
Generic land surface models are generally driven by large-scale data sets to
describe the climate, the soil properties, the vegetation dynamic and the
cropland management (irrigation). This paper investigates the uncertainties
in these drivers and their impacts on the evapotranspiration (ET) simulated
from the Interactions between Soil, Biosphere, and Atmosphere (ISBA-A-gs)
land surface model over a 12-year Mediterranean crop succession. We evaluate
the forcing data sets used in the standard implementation of ISBA over France
where the model is driven by the SAFRAN (Système d'Analyse Fournissant des Renseignements Adaptés à la
Nivologie) high spatial resolution atmospheric
reanalysis, the leaf area index (LAI) time courses derived from the
ECOCLIMAP-II land surface parameter database and the soil texture derived
from the French soil database. For climate, we focus on the radiations and
rainfall variables and we test additional data sets which include the
ERA-Interim (ERA-I) low spatial resolution reanalysis, the Global Precipitation
Climatology Centre data set (GPCC) and the MeteoSat Second Generation (MSG)
satellite estimate of downwelling shortwave radiations.
The evaluation of the drivers indicates very low bias in daily downwelling
shortwave radiation for ERA-I (2.5 W m−2) compared to the negative
biases found for SAFRAN (−10 W m−2) and the MSG satellite (−12 W m−2).
Both SAFRAN and ERA-I underestimate downwelling longwave
radiations by −12 and −16 W m−2, respectively. The SAFRAN and
ERA-I/GPCC rainfall are slightly biased at daily and longer timescales (1
and 0.5 % of the mean rainfall measurement). The SAFRAN rainfall is more
precise than the ERA-I/GPCC estimate which shows larger inter-annual
variability in yearly rainfall error (up to 100 mm). The ECOCLIMAP-II LAI
climatology does not properly resolve Mediterranean crop phenology and
underestimates the bare soil period which leads to an overall overestimation of
LAI over the crop succession. The simulation of irrigation by the model
provides an accurate irrigation amount over the crop cycle but the timing of
irrigation occurrences is frequently unrealistic.
Errors in the soil hydrodynamic parameters and the lack of irrigation in the
simulation have the largest influence on ET compared to uncertainties in the
large-scale climate reanalysis and the LAI climatology. Among climate
variables, the errors in yearly ET are mainly related to the errors in
yearly rainfall. The underestimation of the available water capacity and the
soil hydraulic diffusivity induce a large underestimation of ET over 12 years. The underestimation of radiations by the reanalyses and the absence
of irrigation in the simulation lead to the underestimation of ET while the
overall overestimation of LAI by the ECOCLIMAP-II climatology induces an
overestimation of ET over 12 years.
This work shows that the key challenges to monitor the water balance of
cropland at regional scale concern the representation of the spatial
distribution of the soil hydrodynamic parameters, the variability of the
irrigation practices, the seasonal and inter-annual dynamics of vegetation
and the spatiotemporal heterogeneity of rainfall. |
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