pCO2 variation in ice-covered regions of the Arctic Ocean from the summer 2022 observation

Abstract

To enhance our understanding of the carbon cycle in the Arctic Ocean, comprehensive observational data are crucial, including measurements from the underlying ice water. This study proposed a practical method for calibrating pCO₂ sensor using measured dissolved inorganic carbon and total alkalinity. Our findings suggested the minimum number of bottle samples needed for calibration to ensure 1% accuracy. Additionally, we identified the significant role of a decrease in dissolved inorganic carbon due to photosynthesis and the increase in buffer capacity of the seawater from the release of excess alkalinity by sea ice in regulating pCO₂. The mean air–sea CO₂ fluxes were −48.9 ± 44.6, −7.3 ± 14.6, and −1.4 ± 2.8 mmol m⁻² d⁻¹ in the southern Chukchi Sea, northern Chukchi Sea, and northern East Siberian Sea, respectively. We found a robust negative correlation between the flux and sea ice concentration in the Arctic Sea ice regions.