A global carbon assimilation system based on a dual optimization method

[摘要] Ecological models are effective tools for simulating the distributionof global carbon sources and sinks. However, these models oftensuffer from substantial biases due to inaccurate simulations ofcomplex ecological processes. We introduce a set of scaling factors(parameters) to an ecological model on the basis of plant functionaltype (PFT) and latitudes. A global carbon assimilation system(GCAS-DOM) is developed by employing a dual optimization method(DOM) to invert the time-dependent ecological model parameter stateand the net carbon flux state simultaneously. We use GCAS-DOM toestimate the global distribution of the CO₂ flux on1° × 1° grid cells for the period from 2001 to2007. Results show that land and ocean absorb −3.63 ± 0.50 and −1.82 ±0.16 Pg C yr⁻¹, respectively. North America, Europeand China contribute −0.98 ± 0.15,−0.42 ± 0.08 and −0.20 ±0.29 Pg C yr⁻¹, respectively. The uncertainties inthe flux after optimization by GCAS-DOM have been remarkably reducedby more than 60%. Through parameter optimization, GCAS-DOM canprovide improved estimates of the carbon flux for eachPFT. Coniferous forest (−0.97 ± 0.27 Pg C yr⁻¹)is the largest contributor to the global carbon sink. Fluxes ofonce-dominant deciduous forest generated by the Boreal EcosystemsProductivity Simulator (BEPS) are reduced to−0.78 ± 0.23 Pg C yr⁻¹, the third largestcarbon sink.

[学科分类] 地球化学与岩石