Will the Agulhas extension tend towards a barrier or blender in a changing climate?

This project will explore the dynamics and meridional heat transport of the Agulhas Return Current (ARC), the extension of the Agulhas Current that carries warm subtropical waters eastward along the northern flank of the Antarctic Circumpolar Current. The research will examine mesoscale eddies and meanders, interannual-to-decadal variability, and climate change using a combination of observational data, climate model simulations, and numerical sensitivity experiments to obtain a comprehensive understanding of these processes. The research will be guided by the following questions: How does the ARC vary and what mechanisms dominate? How does differential warming in the Indian and Southern Oceans affect the ARC and its poleward eddy heat flux? How does the ARC respond to opposing wind curl changes over the subtropical and subpolar latitudes and what is the effect on poleward heat flux? This research will advance understanding of the Agulhas Return Current and its variability. The ARC, its eddies and meanders, hold the key to how heat is moved into the Southern Ocean and the system is undergoing rapid change. Regional trends in eddy kinetic energy are complex and their effect on poleward heat flux uncertain. Any change in poleward heat flux involves a competition between large-scale advection, eddy-driven frontogenesis and eddy-induced mixing, requiring a deep dive into ARC eddy dynamics. The work will lead to better understanding of how oceanic heat transport into the Southern Ocean is changing. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.