Ocean components of Earth System Models employed for climate projections as yet do not routinely resolve mesoscale eddies for computational cost reasons, and the associated subgrid processes are still parameterised in these numerical models. While the performance of physics parameterisations in a numerical ocean model is normally assessed via examining the associated physical responses, biogeochemical responses are also important, but are often treated separately. Given recent advances in mesoscale eddy parameterisations, specifically for the eddy induced advection, this work systematically examines the improvements brought about by the inclusion of a time and space varying eddy induced velocity coefficient, and examine the joint consequences for physical and biogeochemical responses in the context of an idealised but ocean relevant model. Relative to a high resolution mesoscale eddy resolving model, the more updated mesoscale eddy parameterisation is able to capture aspects of the model truth in the physical responses. However the biogeochemistry response is rather more subtle, where a 'better' response with the conventional eddy parameterisation with a constant coefficient could arise from a physically inconsistent response. The present work provides some baseline model sensitivities from which future assessments employing other parameterisations or in more complex settings could compare against.

Mesoscale eddies regulate the ocean heat and carbon budgets. However, how and where the kinetic energy flows out from the mesoscale reservoir remains uncertain. In this study, a simplified equation of the mesoscale energy budget is used to obtain a global estimation of the eddy dissipation rate. This framework is first validated in a global ocean model and then applied to a density climatology and a global reconstruction of the eddy kinetic energy field. We find a global disipation rate of 0.66±0.19 TW for the mesoscale kinetic energy, in agreement with recent independent estimates. The results also show an intense dissipation near western boundary currents and in the Antarctic Circumpolar Current, where both large levels of energy and baroclinic conversion occur. The resulting geographical distribution of the dissipation rate brings new insights for closing the ocean kinetic energy budget, as well as constraining future mesoscale parameterizations and associated mixing processes.

Mesoscale eddies play a crucial role in the transport and mixing processes of the global ocean. Their zonal propagation has routinely been predicted using the theoretical phase speed of long baroclinic Rossby waves. However, this long-wave speed is known to be too fast to quantify the eddy zonal propagation equatorward of ~35 latitudes. To address this fundamental issue, this study takes the local eddy wavelengths into account for estimating the eddy zonal propagation globally, whose accuracy is then significantly improved, particularly across mid- to low-latitudes. This improvement hinges upon the observation that mesoscale eddies across mid- to low-latitudes have length scales comparable to the local deformation scales and do not satisfy the long-wave approximation. Additionally, the observed eddy radii from satellite altimetry can be readily used to estimate the local eddy wavelengths. These findings have significant implications for long-range mesoscale eddy propagation behaviors and eddy-driven mixing throughout the global ocean.