Collaborative Research: Natural and anthropogenic controls on the inorganic carbon dynamics in the Chukchi Sea

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As a result of increasing atmospheric carbon dioxide concentrations, the cold waters of the Arctic Ocean and its peripheral seas absorb more and more carbon dioxide from the atmosphere. This process, called ocean acidification, decreases the pH and consumes carbonate ions. Ocean acidification is further enhanced as the Arctic Ocean?s sea ice cover is reduced over longer periods of time each year. The fast chemical changes of the waters are detrimental to many marine organisms. In particular, it makes it more difficult for calcifying organisms to build their calcium carbonate shells or skeletons. Since many of the calcifying organisms exist at the base of the food chain, there are potentially important, but poorly understood, consequences for the marine ecosystem. This project will utilize and improve a numerical model of the physical circulation and biogeochemistry of the Chukchi Sea, a shallow sea peripheral to the Arctic Ocean, to study carbon dynamics and ocean acidification throughout the annual cycle.This project will contribute to STEM workforce development through the provision of support to two early-career scientists during their formative years. It will also provide support for the training of a graduate student. Outreach to a local K-12 Aleut community will be enabled by participation in classroom activities during the annual "Bering Sea Days" on St. Paul Island. The resulting model results will be a resource for related studies of the marine carbon cycle in the Arctic, such as the international Distributed Biological Observatory (DBO) program and the Arctic Marine Biodiversity Observing Network (AMBON).Little is known about the carbon dynamics of the Chukchi Sea in fall, winter and spring due to limited spatial and temporal data coverage in this remote and often inaccessible area. This project will utilize moderately high-resolution three-dimensional ocean and ice circulation regional physical-biogeochemical numerical model (ROMS + COBALT) integrations to study Chukchi Sea carbon dynamics and ocean acidification throughout the year. Hindcasts (1979-present) will be forced by meteorological reanalysis products and will account for lateral transport from the Bering Sea and central Arctic as well as input of organic and inorganic carbon from rivers and sea-ice melt water. Specific project tasks will include: data-based evaluation of the simulated ocean biogeochemistry system fields; characterization of the patterns of carbon dioxide system variability for the Chukchi Sea across time-scales; partition of the underlying physical and biological mechanisms; quantification of the downstream transport of organic and inorganic carbon using dye tracers and Lagrangian floats; and analysis of the sensitivity of ecosystem processes to ocean acidification.