The Chukchi Sea in a changing environment: A synthesis of modeling and observations

The Chukchi Sea is an important biogeochemical gateway into the Arctic Ocean. Rising temperatures, loss of sea ice, enlarged freshwater input, increases in frequency and magnitude of storms, and ocean acidification are likely to transform the biogeochemistry and ecosystem of this pristine shelf sea. However, due to limited spatial and temporal data coverage in this remote and often inaccessible area, little is known about the present day carbon dynamics in fall, winter, and spring. Frequent but poorly studied late-season mixing episodes on the Chukchi Shelf may be important drivers of the marine carbon budget and the intensity and duration of ocean acidification events as they alter the degree to which carbon is retained on the shelf, released to the atmosphere, or mobilized and transported into the Arctic Ocean. While loss of sea ice could increase productivity and temporarily increase surface aragonite saturation state, melt water dilutes the carbonate ion concentration and thereby decreases the aragonite saturation state. Here, we integrate results from a 3-D ocean circulation, sea ice and biogeochemistry model ROMS-COBALT (Regional Ocean Modeling System-Carbon, Ocean, Biogeochemistry and Lower Trophics) hindcast simulation with observations from the new Chukchi Ecosystem Observatory to get a better understanding of the seasonal to interanual variability and underlying drivers of the regional inorganic carbon system. The model is used to expand the observational timeseries in time and space to shed light on the impact of global climate variability and trends on the Chukchi Sea CO2 system.