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M. Scholze, S. Blessing, W. Dorigo, R. Giering, J. Grant, T. Kaminski, W. Knorr, C. Köstler, C. Paulik, G. Schürmann, K. Scipal, M. Vossbeck, S. Zaehle:
"Simultaneous assimilation of three EO data streams into two global terrestrial ecosystem models to constrain land - atmosphere exchange fluxes";
Talk: 4th iLEAPS Science Conference "Terrestrial ecosystems, atmosphere, and people in the Earth system", Nanjing, China; 2014-05-12 - 2014-05-16.

Within the European Space Agency's (ESA) CarbonFlux project three Earth Observation (EO) data products are assimilated into two models of the terrestrial carbon cycle. The EO products are soil moisture provided by ASCAT/AMSR-E, Fraction of Photosynthetically Active Radiation (FAPAR) derived by the Two-stream Inversion Package (TIP) from MODIS broadband albedo, as well as column-integrated atmospheric CO2 (XCO2) derived from SCIAMACHY.
Using the derivative-based variational Carbon Cycle Data Assimilation System (CCDAS) approach, these data streams are applied in a mathematically rigorous way together with prior information to act as simultaneous constraints on process parameters/initial conditions in the Biosphere Energy Transfer HYdrology Scheme (BETHY) and the Jena Scheme for Biosphere-Atmosphere Coupling in Hamburg (JSBACH) models.
The calibrated models provide an integrated, consistent with the observational data view on global land-atmosphere exchange fluxes. Using second-derivative information, we infer posterior parameter/initial state uncertainties and map them forward onto simulated net and gross surface carbon fluxes over multiple scales. Thus the two CCDASs deliver fluxes including their uncertainty ranges consistent with the EO input products, which allows a rigorous assessment of the indirect constraint on carbon fluxes provided by the EO products.
We present first results from the CarbonFlux project including the validation against independent observations and comparison with further CCDAS products derived through assimilation of different data streams, such as flask samples of the atmospheric CO2 concentrations.