A global carbon assimilation system based on a dual optimization method

Abstract

Abstract. Ecological models are effective tools for simulating the distribution of global carbon sources and sinks. However, these models often suffer from substantial biases due to inaccurate simulations of complex ecological processes. We introduce a set of scaling factors (parameters) to an ecological model on the basis of plant functional type (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 state and the net carbon flux state simultaneously. We use GCAS-DOM to estimate the global distribution of the CO 2 flux on 1 • × 1 • grid cells for the period from 2001 to 2007. Results show that land and ocean absorb −3.63 ± 0.50 and −1.82 ± 0.16 Pg C yr −1 , respectively. North America, Europe and China contribute −0.98 ± 0.15, −0.42 ± 0.08 and −0.20 ± 0.29 Pg C yr −1 , respectively. The uncertainties in the flux after optimization by GCAS-DOM have been remarkably reduced by more than 60 %. Through parameter optimization, GCAS-DOM can provide improved estimates of the carbon flux for each PFT. Coniferous forest (−0.97 ± 0.27 Pg C yr −1 ) is the largest contributor to the global carbon sink. Fluxes of once-dominant deciduous forest generated by the Boreal Ecosystems Productivity Simulator (BEPS) are reduced to −0.78 ± 0.23 Pg C yr −1 , the third largest carbon sink.

基于大气CO<sub>2</sub>浓度和生态碳通量模型的土壤碳库优化方法

“…大气传 输模型采用MOZART-4(Model for Ozone and Related Chemical Tracer, version 4) [19] . 1°网格分辨率优化碳 通量计算方法采用窗口双优化算法DOM [17,18] . Figure 2 Parameter estimation results of soil carbon pools at a horizontal resolution of 1° × 1°, where pink and red represent the value is bigger than one, which means the initial soil carbon pools are underestimated, but cyan and blue represent the value is less than one, which means the initial soil carbon pools are overestimated.…”

If Some Critical Regions Achieve Carbon Neutrality, How Will the Global Atmospheric CO2 Concentration Change?

“…Wang et al [13] used the GEOS-Chem model to simulate the CO 2 concentration and changes over China from 2004 to 2012. MOZART [14] is a tropospheric global chemical transport model, based on which Zheng et al [15] developed a global carbon assimilation system (GCAS-DOM). Base et al [16] evaluated the uncertainty of simulating CO 2 using five atmospheric transport models (ACTM, LMDZ, GEOS-Chem, PCTM, and TM5).…”

Optimization of Terrestrial Ecosystem Model Parameters Using Atmospheric CO2 Concentration Data With the Global Carbon Assimilation System (GCAS)

“…This study aims at exploring spatiotemporal variations of TBM parameters using atmospheric CO 2 concentration data through the newly developed Global Carbon Assimilation System (GCAS). GCAS is developed for optimizing global land surface net carbon fluxes and TBM parameters at 1° resolution at weekly time intervals (Chen et al, ; Zhang et al, , ; Zheng et al, , ).…”