Is the Southern Ocean a Major Sink for Anthropogenic Carbon?

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ABSTRACTOCE-0327189Numerical models predict that the Southern Ocean is disproportionately important in the oceanic uptake of anthropogenic carbon dioxide. For this reason, scientists from Princeton University propose to evaluate the role of Southern Ocean in the uptake of anthropogenic carbon. The investigators believe that the primary mechanisms responsible for the large uptake of carbon in this region without leaving a large in-situ inventory is lateral transport towards the north associated with the formation of Sub-Antarctic Mode Water (SAMW) and Antarctic Intermediate Water (AAIW). To attain this goal, this team of investigators plans to determine how much anthropogenic carbon dioxide is found in the SAMW and AAIW, identify the pathways by which anthropogenic carbon dioxide enters the ocean and assess how the models simulate these pathways. The scientists hypothesize that advection of waters along isopycnal surfaces that outcrop in the Subantartic and Antarctic Zone is the most important pathway and suggests that differences between the models arise largely from differences in the forcing of this advection by the wind stress field in the Southern Ocean. To test the hypothesis, the following tasks will be carried out: (1) evaluate and reduce biases in the estimation of anthropogenic carbon dioxide and apply a new water mass analysis technique to assign this to specific water masses; (2) examine the mechanisms that determine the water mass distribution and anthropogenic carbon dioxide burden by performing a set of model sensitivity studies in which winds are varied in the Southern Ocean in both a level-coordinate and new isopycnal circulation model; (3) quantitatively evaluate model-data consistency by performing inverse calculations based on observed inventories and model circulation fields; and (4) determine what types of field measurements would be most appropriate for monitory future uptake and improving our understanding of basic processes. Results from this study will improve our understanding of the processes that determine the uptake of anthropogenic carbon in the Southern Ocean