Decadal Changes and Implications for Air-Sea Exchange of CO2 in the East China Sea

The role of the productive East China Sea (ECS) in regulating the anthropogenic CO₂ and effect of environmental changes on CO₂ uptake changes are being revealed gradually. Here we report the synthesis of time-series data of the annual mean CO₂ fluxes since 1980 based on both observations and model calculation. This assessment of annual CO₂ uptake is more reliable and complete, compared to previous estimates, in terms of temporal and spatial coverage. Additionally, the CO₂ time-series exhibits distinct seasonal pattern and also reveals apparent inter-annual variations. The flux seasonality shows a strong sink in spring and a weak source in the period from late summer to mid fall. The weak sink status during warm periods in summer-fall is fairly sensitive to changes of pCO₂ and may easily shift from a sink to a source due to environmental changes. Finally, the effects of the Changjiang river discharge (CRD) and the Kuroshio strength on the CO₂ uptake have been discerned and future changes due to the CRD fluctuation are examined; i.e. how the CO₂ uptake in the ECS is controlled by the CRD fluctuation and the Kuroshio strength, which, in turn, are influenced by climate change and anthropogenic forcing, has been investigated as well.