Publications by David Marshall

Resolving and parameterising the ocean mesoscale in earth system models

Current Climate Change Reports Springer Nature 6 (2020) 137-152

H Hewitt, M Roberts, P Mathiot, D Marshall, et al.

Purpose of ReviewAssessment of the impact of ocean resolution in Earth System models on the mean state, variability, andfuture projections and discussion of prospects for improved parameterisations to represent the ocean mesoscale.Recent FindingsThe majority of centres participating in CMIP6 employ ocean components with resolutions of about 1 degree intheir full Earth System models (eddy-parameterising models). In contrast, there are also models submitted to CMIP6 (both DECKand HighResMIP) that employ ocean components of approximately 1/4 degree and 1/10 degree (eddy-present and eddy-richmodels). Evidence to date suggests that whether the ocean mesoscale is explicitly represented or parameterised affects not onlythe mean state of the ocean but also the climate variability and the future climate response, particularly in terms of the Atlanticmeridional overturning circulation (AMOC) and the Southern Ocean. Recent developments in scale-aware parameterisations ofthe mesoscale are being developed and will be included in future Earth System models.SummaryAlthough the choice of ocean resolution in Earth System models will always be limited by computational consider-ations, for the foreseeable future, this choice is likely to affect projections of climate variability and change as well as otheraspects of the Earth System. Future Earth System models will be able to choose increased ocean resolution and/or improvedparameterisation of processes to capture physical processes with greater fidelity.

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