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Global Carbon Flux and Biomass Pools Simulated Using SiB4
Katherine
Haynes, Colorado State University, kdhaynes@atmos.colostate.edu
Ian
Baker, Colorado State University, baker@atmos.colostate.edu
(Presenter)
Scott
Denning, Colorado State University, denning@atmos.colostate.edu
We simulate fully self-consistent global carbon flux and biomass pools using the latest version of the Simple Biosphere Model (SiB4). SiB4 is an enzyme-kinetic/process-based model that simulates biophysical mechanisms important for surface-atmosphere exchange. Environmental cues and simulated photosynthesis determine phenology, and carbon uptake is allocated into multiple above- and belowground live and dead pools; transfer coefficients determine exchange between pools, and mechanistic respiration ‘closes the loop’ for a fully self-consistent carbon cycle.
SiB4 diagnostics are evaluated against eddy covariance flux and site-based observations across multiple Plant Functional Types (PFTs). We also confront the model with spectrally-based observations of Leaf Area Index (LAI), fraction of Photosynthetically Active Radiation absorbed (fPAR) and Solar Induced Fluorescence (SIF) for evaluation across broad spatiotemporal scales. We can also isolate the photosynthesis component of the carbon cycle using evaluations of surface uptake of carbonyl sulfide (OCS).
SiB4 simulates reasonable estimates of global Gross Primary Productivity (GPP) and global aboveground biomass. Seasonality in mid- and high-latitudes is reproduced. Biomass in tropical forests is reproduced, but simulated seasonality in carbon flux conflicts with some observations. Some regions of tropical savanna are overproductive, but overall SiB4 shows excellent fidelity when evaluated across multiple observational platforms.
Associated Project(s):
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