Eddy fluxes across the Southern Antarctic Circumpolar Current Front near Southeast Indian Ridge

Principal Investigators: Kathleen Donohue and D. Randolph Watts

Ocean circulation regulates the Earth's climate by transporting heat and carbon through the global ocean and storing heat and carbon in the deep ocean. In the Southern Ocean, the strongest current on earth, the Antarctic Circumpolar Current (ACC), distributes heat, salt, and freshwater between ocean basins. This project seeks to use moored instrumentation to quantify the exchange of heat and salt across the southernmost portion of the Antarctic Circumpolar Current (ACC) into the waters around Antarctica in a sector where the ACC fronts are in close proximity and mesoscale eddy activity is particularly high. The project coordinates US and Korean observational and modeling components. The instrumentation and modeling will expand and augment an already funded Korean program. Ship time needed to deploy and recover the instruments will be provided South Korea. Data from the moored instruments will be collected annually by telemetry via pop-up data shuttles, leaving the instruments undisturbed on the seafloor. The observations will be used to refine and verify global proxy estimates of heat fluxes. Global context for understanding the heat budget will be guided by a high-resolution numerical model.

The goal of this project is to measure and diagnose ocean eddy heat fluxes in the lee of Southeast Indian Ridge in the ACC. This location stands out as one of the major ACC eddy flux hot spots and as a region where the three ACC fronts converge closely together as they encounter the ridge complex. At this hot spot, mean and eddy fluxes likely conspire to cross the breadth the ACC. The focus is upon the southernmost ACC front where existing in situ measurements are sparse and where ACC-sourced heat influences the Southern Ocean Ross and Weddell gyres and ultimately the Antarctic margin. A high-resolution numerical model will provide the larger context for proposed observations, and proxy estimates will be sought that use the existing global observing system.

SEIR is funded by the National Science Foundation under Award Number 2023306.

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