Mesoscale Eddies Regulate Seasonal Iron Supply and Carbon Drawdown in the Drake Passage

Abstract

AbstractThe Southern Ocean is a major region for uptake of anthropogenic carbon. The transport of carbon and nutrients are dominated by the Antarctic Circumpolar Current and its rich mesoscale eddy field; however, the current generation of Earth System Models (ESMs) lack the resolution to resolve eddies. Here we show that a computational model that explicitly represents mesoscale eddies can reproduce observed phases and amplitudes of seasonal biological productivity and partial pressure of carbon dioxide. Our sensitivity study demonstrates that when eddies are suppressed or parameterized, the model cannot reproduce these seasonal cycles. Experiments with suppressed eddy activity show that the lack of eddies significantly changes the iron supply and phenology of phytoplankton blooms. The mismatch in the timing and intensity of the bloom causes significant biases in the seasonal carbon cycle of the region with implications to the enigmatic biases in partial pressure of carbon dioxide among the state‐of‐the‐art ESMs.