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