| Summary: | Sea ice may be an active source or sink for climatically significant gases such as CO2 and CH4. The dynamics of these biogeochemically active gases within sea ice are still not well understood. Modeling can help to identify and calibrate the physical and biogeochemical processes that affect gas production, consumption, diffusion and transport within sea ice. In this study, we aim at constraining the dynamics of carbon dioxide (CO2) within sea ice using observation data and a one-dimensional halo-thermodynamic sea ice model, including gas physics and biogeochemistry. The incorporation and transport of dissolved CO2 within sea ice, as well as its rejection via gas-enriched brine drainage to the ocean, are modeled following fluid transport equations through sea ice. Gas bubbles nucleate within sea ice when CO2 concentration is above saturation. These bubbles rise to the ice surface due to their own buoyancy when the brine network is connected. Different formulations are tested for the CO2 fluxes between sea ice and the atmosphere (including wind speed, the presence/absence of snow and the differential partial pressure of CO2 between sea ice brines and the atmosphere). The consumption and release of CO2 by primary production and respiration are modeled. Finally, the precipitation and dissolution of ikaite (CaCO3) which influences CO2 concentration within sea ice are modeled. A simulation corresponding to a case study covering the seasonal growth of first-year ice at Point Barrow, Alaska, was run. How specific gas processes affect CO2 dynamics within Arctic sea ice will be discussed.
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