Collaborative Research: NSFGEO-NERC: QUICCHE: Quantifying Interocean fluxes in the Cape Cauldron Hotspot of Eddy kinetic energy

This is a project that is jointly funded by the National Science Foundation’s Directorate of Geosciences (NSF/GEO) and the National Environment Research Council (UKRI/NERC) of the United Kingdom (UK) via the NSF/GEO-NERC Lead Agency Agreement. This Agreement allows a single joint US/UK proposal to be submitted and peer-reviewed by the Agency whose investigator has the largest proportion of the budget.

Upon successful joint determination of an award, each Agency funds the proportion of the budget and the investigators associated with its own ivestigators and component of the work.

The Cape Basin in the southeast Atlantic is a global hotspot of eddy kinetic energy, fed by a leakage of waters from the subtropical Indian Ocean via the Agulhas Current. A proportion of warm and salty Agulhas waters is vigorously stirred and mixed into the cooler and fresher Atlantic by co-interacting rings and eddies. This project will address the hypothesis that a large proportion of the Indian Ocean waters that leak into the Atlantic is to be found in submesoscale (less than approximately 1 km) features generated by deformations of the mesoscale (tens to hundreds of km) flow field.

The project will observe and characterize, for the first time, submesoscale features generated by mesoscale recirculations within the Cape Cauldron. The observations will be used to estimate Agulhas leakage fluxes with theoretical eddy diffusivity and eddy flux frameworks. The results will be related to new and existing satellite altimeter observations to infer variability in Agulhas leakage.

Outreach and education activities include production of two short films aboard ship, student and intern visits to the ship, hands-on experience building ocean drifters at Miami high schools, and creation of a popular science article and an educational, oceanographic card game for school children.

This project will entail the collection of new observations within the Cape Basin of filamentation and eddy interaction to measure the related submesoscale features and estimate diffusivities. These measurements will be used to quantify eddy heat and salt fluxes. Observations will be made using both Eulerian and Lagrangian instrumentation, including moorings, an undulating CTD system, gliders, drifters, profiling floats, and microstructure turbulence profilers, capturing time and space scales from hours to seasons and from 1 to 100 km.

The observations will be synthesized and analyzed with other datasets including measurements from the SWOT crossover in the Cape Basin and output from an ocean model. The observations will also be used to evaluate the new NASA SWOT (Surface Water and Ocean Topography) satellite mission at a swatch crossover point in the study region.

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.