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| Titel |
Sensitivity and predictive uncertainty of the ACASA model at a spruce forest site |
| VerfasserIn |
K. Staudt, E. Falge, R. D. Pyles, Paw U. K. T., T. Foken |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1726-4170
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| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 7, no. 11 ; Nr. 7, no. 11 (2010-11-17), S.3685-3705 |
| Datensatznummer |
250005064
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| Publikation (Nr.) |
 copernicus.org/bg-7-3685-2010.pdf |
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| Zusammenfassung |
The sensitivity and predictive uncertainty of the Advanced
Canopy-Atmosphere-Soil Algorithm (ACASA) was assessed by employing the
Generalized Likelihood Uncertainty Estimation (GLUE) method. ACASA is a
stand-scale, multi-layer soil-vegetation-atmosphere transfer model that
incorporates a third order closure method to simulate the turbulent exchange
of energy and matter within and above the canopy. Fluxes simulated by the
model were compared to sensible and latent heat fluxes as well as the net
ecosystem exchange measured by an eddy-covariance system above the spruce
canopy at the FLUXNET-station Waldstein-Weidenbrunnen in the Fichtelgebirge
Mountains in Germany. From each of the intensive observation periods carried
out within the EGER project (ExchanGE processes in mountainous Regions) in
autumn 2007 and summer 2008, five days of flux measurements were selected. A
large number (20000) of model runs using randomly generated parameter sets
were performed and goodness of fit measures for all fluxes for each of these
runs were calculated. The 10% best model runs for each flux were used for
further investigation of the sensitivity of the fluxes to parameter values
and to calculate uncertainty bounds.
A strong sensitivity of the individual fluxes to a few parameters was
observed, such as the leaf area index. However, the sensitivity analysis
also revealed the equifinality of many parameters in the ACASA model for the
investigated periods. The analysis of two time periods, each representing
different meteorological conditions, provided an insight into the seasonal
variation of parameter sensitivity. The calculated uncertainty bounds
demonstrated that all fluxes were well reproduced by the ACASA model. In
general, uncertainty bounds encompass measured values better when these are
conditioned on the respective individual flux only and not on all three
fluxes concurrently. Structural weaknesses of the ACASA model concerning the
soil respiration calculations and the simulation of the latent heat flux
during dry conditions were detected, with improvements suggested for each. |
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