资源环境科技发展态势分析平台

We compare air-sea CO₂ exchange in an ensemble of global ocean hindcast models to a suite of observation-based products for 1990-2018. Individual products agree closely for regional fluxes, but individual models vary widely in their regional estimates. Despite their regional divergence, individual models estimate similar global mean fluxes, indicating that significant regional compensation occurs to balance in the global integral. Models diverge most strongly from the observed mean flux in the northern and southern subtropics, despite strong agreement in seasonality. In the Southern Ocean, models estimate a wide range of both mean and seasonality. The ensemble of observation-based products can be used to select the models that best represent the regionally-resolved mean state of air-sea CO₂ exchange. Three models are within 3σ of the observed estimates in all regions. With this selected model ensemble, the global mean flux is slightly reduced and its uncertainty is reduced by 35%.