What Controls the Variability of the Southern Ocean Productivity and Carbon Uptake?

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The variability of the biological productivity and correspondingly the carbon uptake, including fossil fuel CO2, of the Southern Ocean are hampered by our incomplete understanding of the responses of the marine ecosystems to physical forcings, oceanic transport and climate change. This modeling study will address three main questions: i) what are the mechanism that link climate dynamics and biological production? ii) what are the mechanisms for micronutrient iron limitation and the relative importance of different iron sources? and iii) what are the roles of mesoscale eddies on regional carbon and iron budgets? Based on the MIT ocean general circulation model (MITgcm), eddy permitting (1/60 x 1/60 lat lon; 42 depth levels) physical circulation fields from the Southern Ocean State Estimate will be constrained by a very large observational data set of Southern ocean properties. Model simulations, with improved representations of iron sources from continental shelves, and including the interplay between increasing partial pressure (pCO2) in the atmosphere and upwelling of cold CO2 rich waters, will be tested against the observed variability of surface chlorophyll and biogeochemical tracers. This research should yield a more authentic estimate of the carbon, and iron budgets for recent and future years. Educational aspect of the project will train a graduate student and undergraduate student interns in earth-system modeling at Georgia Institute of Technology.