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| Titel |
Consistent assimilation of MERIS FAPAR and atmospheric CO2 into a terrestrial vegetation model and interactive mission benefit analysis |
| VerfasserIn |
T. Kaminski, W. Knorr, M. Scholze, N. Gobron, B. Pinty, R. Giering, P.-P. Mathieu |
| 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 ; 9, no. 8 ; Nr. 9, no. 8 (2012-08-16), S.3173-3184 |
| Datensatznummer |
250007241
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| Publikation (Nr.) |
 copernicus.org/bg-9-3173-2012.pdf |
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| Zusammenfassung |
The terrestrial biosphere is currently a strong sink for anthropogenic
CO2 emissions. Through the radiative properties of CO2, the
strength of this sink has a direct influence on the radiative budget
of the global climate system. The accurate assessment of this sink and
its evolution under a changing climate is, hence, paramount for any
efficient management strategies of the terrestrial carbon sink to
avoid dangerous climate change. Unfortunately, simulations of carbon
and water fluxes with terrestrial biosphere models exhibit large
uncertainties. A considerable fraction of this uncertainty
reflects uncertainty in the parameter values of the process
formulations within the models.
This paper describes the systematic calibration of the process
parameters of a terrestrial biosphere model against two observational
data streams: remotely sensed FAPAR (fraction of absorbed
photosynthetically active radiation) provided by the MERIS (ESA's Medium Resolution Imaging Spectrometer) sensor and
in situ measurements of atmospheric CO2 provided by the
GLOBALVIEW flask sampling network. We use the Carbon Cycle Data
Assimilation System (CCDAS) to systematically calibrate some
70 parameters of the terrestrial BETHY (Biosphere Energy Transfer Hydrology) model. The
simultaneous assimilation of all observations provides parameter
estimates and uncertainty ranges that are consistent with the
observational information. In a subsequent step these parameter
uncertainties are propagated through the model to uncertainty ranges
for predicted carbon fluxes.
We demonstrate the consistent assimilation at global
scale, where the global MERIS FAPAR product and atmospheric
CO2 are used simultaneously. The assimilation
improves the match to independent observations. We quantify how MERIS
data improve the accuracy of the current and future (net and gross)
carbon flux estimates (within and beyond the assimilation period).
We further demonstrate the use of an interactive mission benefit
analysis tool built around CCDAS to support the design of future space
missions. We find that, for long-term averages, the benefit of FAPAR
data is most pronounced for hydrological quantities, and moderate for
quantities related to carbon fluxes from ecosystems. The benefit for
hydrological quantities is highest for semi-arid tropical or
sub-tropical regions. Length of mission or sensor resolution is of
minor importance. |
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