Seasonal variation of CO2 air-sea flux and effects of warming in the Kuroshio Current of the East China Sea

The partial pressure of CO₂ (pCO₂) and associated CO₂ air-sea flux exhibit highly heterogeneous temporal and spatial patterns in ocean margins. In this study, we analyzed a three-year time-series of data sampled during 2011–2014 along the Kuroshio Current within the East China Sea (ECS) to investigate the seasonal pattern of carbonate chemistry and CO₂ air-sea fluxes. Annually, the Kuroshio within the ECS operates as a net CO₂ sink at approximately 1.3 mol C m⁻² yr⁻¹, less than estimates over the ECS shelf (∼1.8 mol C m⁻² yr⁻¹). The thermal control of pCO₂ makes the Kuroshio a strong CO₂ sink in winter, with a transition to net-neutral, or a weak CO₂ source in summer. On an interannual basis, however, the seasonal CO₂ air-sea fluxes in the Kuroshio may undergo shifts if warming conditions continue.