FEOTS: A New Offline Code for the Fast Equilibration of Tracers in the Ocean

In this paper we introduce a new software framework for the offline calculation of tracer transport in the ocean. The Fast Equilibration of Ocean Tracers Software (FEOTS) is an end-to-end set of tools to efficiently calculate tracer distributions on a global or regional sub-domain using transport operators diagnosed from a comprehensive ocean model. To the best of our knowledge, this is the first application of a Transport Matrix Model to an eddying ocean state. We demonstrate the capabilities of FEOTS in an application focused on the Argentine Basin, where intense eddy activity and the Zapiola Anticyclone lead to strong mixing of water masses. The demonstration clearly shows the benefits of the approach, while at the same time highlighting the limitations of the Impulse Response Functions approach in capturing tracer transports by a non-linear advection scheme. Our future work will focus on improving the computational efficiency of the code to reduce time-to-solution, and on using different basis functions to better represent non-linear advection operators.