Quantifying Interocean Fluxes across the Cape Cauldron Hotspot of Eddy Kinetic Energy

The Agulhas current carries warm and salty subtropical Indian Ocean water south along the coast of east Africa. Past the Cape of Good Hope, the Agulhas Current overshoots the tip of the African continent and turns back towards the Indian Ocean, throwing lots of eddies into the south Atlantic across the Cape Basin, located southwest of South African coast. These eddies are large rotating vortex rings that interact with each other, sometimes merging, sometimes breaking up into smaller structures. All together this energetic flow field moves northwest across the Cape Basin carrying heat and salt into the fresher south Atlantic. It turns out this influx of heat and salt from the Indian Ocean is really important for the large-scale overturning circulation of our oceans which redistribute heat and salt from basin to basin and across latitudes in a way that helps control our climate. However, measuring the heat and sal flux from the Indian to Atlantic Oceans is not trivial because of the chaotic nature of the flow field. We propose a novel set of measurements that will let us measure the heat and salt fluxes, not just in the really large eddies that can be seen from space (aka Agulhas Rings), but also the smaller eddying features whose contribution to the interocean fluxes is still unaccounted for. These measurements include moorings, ocean turbulence, fine-resolution hydrographic surveys, seagliders and two different types of lagrangian drifters set to measure at the surface and at 2000-m depth. In addition, we will make these measurements at a time that coincides with the science calibration phase of the upcoming SWOT satellite, so as to provide ground-truthed data for that mission.