Estimated regional CO₂ flux and uncertainty based on an ensemble of atmospheric CO₂ inversions

Abstract. Global and regional sources sinks of carbon across the earth's surface have been studied extensively using atmospheric dioxide (CO2) observations chemistry-transport model (ACTM) simulations (top-down/inversion method). However, uncertainties in flux distributions remain unconstrained due to lack high-quality measurements, simulations, representation data errors inversion systems. Here, we assess a suite 16 cases derived from single transport (MIROC4-ACTM) but different sets priori (bottom-up) terrestrial biosphere oceanic fluxes, as well prior observational (50 sites) estimate CO2 fluxes for 84 regions over period 2000–2020. The ensembles provide mean field that is consistent with global growth rate, land ocean sink partitioning ?2.9 ± 0.3 (± 1? uncertainty on ensemble mean) ?1.6 0.2 PgC yr?1, respectively, 2011–2020 (without riverine export correction), offsetting about 22 %–33 % %–18 fossil fuel emissions. rivers carry 0.6 yr?1 into deep ocean, thus effective ?2.3 ?2.2 0.3, respectively. Aggregated 15 compare reasonably best estimations 2000s (? 2000–2009), given by REgional Carbon Cycle Assessment Processes (RECCAP), all appeared 2011–2020. Interannual variability seasonal cycle are more consistently two distinct when greater degree freedom (increased uncertainty) system. We further evaluated meridional independent (not used inversions) aircraft suggesting (model–observation standard deviation = ?0.3 3 ppm) suited budgets than an individual ?0.35 3.3 ppm). Using 11 at 5-year intervals, show promise capability track changes toward supporting ongoing future emission mitigation policies.