Sea surface pCO2-SST relationships across a cold-core cyclonic eddy:: Implications for understanding regional variability and air-sea gas exchange

This study is designed to improve the understanding of how biologically productive, cold-core cyclonic eddies affect sea surface pCO(2) in the lee of the main Hawaiian Islands in the subtropical North Pacific Gyre. We identified three unique relationships between pCO(2) and sea surface temperature (SST). A positive correlation between pCO(2) and SST was observed in the waters surrounding the eddy suggesting surface CO2 is controlled primarily by thermodynamics. In contrast, a negative relationship was observed within the eddy core as a result of the upwelling of CO2-enriched subsurface waters. A third relationship existed throughout the rest of the eddy with reduced pCO(2) suggesting a combination of biological uptake, physical upwelling and thermodynamic controls. In the absence of an eddy, this region is a CO2 sink, with the passage of the cold-core mesoscale eddy decreasing the magnitude of the sink by similar to 17%. However, if the general temperature correlation is used to predict pCO(2) inside the cold eddy, it would overestimate the CO2 sink inside the eddy by 100%.