Title: Carbon and fAPAR Assimilation within CCDAS
Citation: Proceedings of ECMWF/ELDAS Workshop on Land Surface Assimilation p. 213-219
Publication Year: 2005
JRC N°: JRC31181
URI: http://publications.jrc.ec.europa.eu/repository/handle/JRC31181
Type: Articles in periodicals and books
Abstract: We present the Carbon Cycle Data Assimilation System (CCDAS), which is built around the Biosphere Energy Transfer HYdrology Scheme (BETHY), coupled to the atmospheric transport model TM2. In its current form, the system uses a two-step assimilation procedure to estimate 57 model parameters from both satellite observed vegetation activity and atmospheric carbon dioxide samples. Observational uncertainties are mapped back on parameter uncertainties. These parameter uncertainties are then projected forward to important diagnostics such as regional carbon budgets. CCDAS includes BETHY's adjoint, Jacobian, and Hessian codes, which are provided by automatic differentiation (AD) of the BETHY code. This automated procedure allows quick updates of CCDAS after modifications of BETHY. We also report on the preparation of fraction of Absorbed Photosynthetically Active Radiation (fAPAR) data provided by SeaWiFS for use in CCDAS. Analysis of this fAPAR data suggests a time lag against precipitation of one to several months. A reaction of the terrestrial biosphere at such timescales carries promises for medium-range to seasonal prediction.
JRC Directorate:Sustainable Resources

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