An important element to keep track of global change is the atmosphere–water exchange of carbon dioxide (CO2) in the ocean as it provides insight in how much CO2 is incorporated in the ocean (i.e. the ocean as a sink for CO2) or emitted to the atmosphere (i.e. the ocean as a source). To date, only few high-resolution observation sets are available to quantify the spatiotemporal variability of air–sea CO2 fluxes. In this study, we used observations of pCO2 collected daily at the ICOS station Thornton Buoy in the southern North Sea from February until December 2018 to calculate air–sea CO2 fluxes. Our results show a seasonal variability of the air–sea carbon flux, with the sea being a carbon sink from February until June switching to a carbon source in July and August, before switching back to a sink until December. We calculated that the sink was largest in April (−0.95 ± 0.90 mmol C m−2 d−1), while in August, the source was at its maximum (0.08 ± 0.13 mmol C m−2 d−1). On an annual basis, we found a sink for atmospheric CO2 of 130.19 ± 149.93 mmol C m−2 y−1. Apart from region- and basin-scale estimates of the air–sea CO2 flux, also local measurements are important to grasp local dynamics of the flux and its interactions with biogeochemical processes. |
