On a minimum set of equations for parameterisations in comprehensive ocean circulation models

TL;DR

This study investigates the minimal set of equations that need parameterisation in comprehensive ocean models to balance simplicity and accuracy, focusing on the Gulf Stream in a North Atlantic configuration.

Contribution

It identifies that only tracer equations for temperature and salinity require parameterisation, simplifying model development while maintaining large-scale flow accuracy.

Findings

Parameterising only tracer equations suffices for accurate Gulf Stream representation.

Hydrodynamic and atmospheric equations can remain unmodified without loss of accuracy.

Simplifies the development of ocean circulation models by reducing the number of equations to parameterise.

Abstract

The complexity of comprehensive ocean models poses an important question for parameterisations: is there a minimum set of equations that should be parameterised, on the one hand, to reduce the development to a minimum, and, on the other hand, to ensure an accurate representation of large-scale flow patterns? This work seeks to answer this to assist modern parameterisations be more selective in their targets. For this, we considered a North Atlantic configuration of the MIT general circulation model and studied contributions of different model equations to the accuracy of representation of the Gulf Stream at low resolution. Our results suggest that it is enough to parameterise only the tracer equations for temperature and salinity and leave the other equations in the hydrodynamic part, as well as the atmospheric model unmodified.