FEOTS v0.0.0: 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. While a Newton-Krylov-based equilibration capability is still under development and not presented here, we demonstrate in this paper the transient modeling 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 illustrates progress in developing offline passive tracer simulation capabilities, while highlighting the challenges 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, using different basis functions to better represent non-linear advection operators, applying FEOTS to a parent model with unstructured grids (Ocean Model for Prediction Across Scales, MPAS-Ocean), and fully implementing a Newton-Krylov steady-state solver.

Automated summary

In this paper, we present a new offline calculation software framework called FEOTS for tracer transport in the ocean. FEOTS is a set of tools that efficiently calculates tracer distributions using transport operators diagnosed from an ocean model. This paper demonstrates the transient modeling capabilities of FEOTS in the Argentine Basin, highlighting the challenges of capturing tracer transports using a non-linear advection scheme with impulse response functions. Future work will focus on improving computational efficiency, implementing a steady-state solver, and applying FEOTS to a model with unstructured grids.