The resulting eddies are formed at a characteristic scale called the Rossby deformation radius. This scale depends on the strength of stratification and the coriolis parameter (which in turn depends on the latitude). As a result, baroclinic eddies form on scales of around 1° (~100 km) at the tropics, but less than 1/12° (~10 km) at the poles and in some shelf seas. Most climate models, such as those run as part of CMIP experiments, are run at a resolution of 1-1/4° in the ocean, and can therefore not resolve baroclinic eddies across large parts of the ocean, particularly at the poles. However, high-latitude baroclinic eddies are important for many ocean processes such as the Atlantic Meridional Overturning Circulation (AMOC), which affects global climate. As a result, the effects of eddies are parameterised in climate models, such as through the widely-used Gent-McWilliams (GM) parameterisation which represents the isopycnal-flattening effects of eddies as a diffusivity. This parameterisation is not perfect - for instance, it may overpredict the sensitivity of the Antarctic Circumpolar Current and AMOC to the strength of winds over the Southern Ocean. As a result, alternative parameterisations are being developed to improve the representation of eddies in ocean models.
