Resolving and parameterising the Ocean Mesoscale in earth system models

Abstract

This article is part of the Topical Collection on Advances and Future Directions in Earth System Modelling

Purpose of Review Assessment of the impact of ocean resolution in Earth System models on the mean state, variability, and future projections and discussion of prospects for improved parameterisations to represent the ocean mesoscale.

Recent Findings The majority of centres participating in CMIP6 employ ocean components with resolutions of about 1 degree in their full Earth System models (eddy-parameterising models). In contrast, there are also models submitted to CMIP6 (both DECK and HighResMIP) that employ ocean components of approximately 1/4 degree and 1/10 degree (eddy-present and eddy-rich models). Evidence to date suggests that whether the ocean mesoscale is explicitly represented or parameterised affects not only the mean state of the ocean but also the climate variability and the future climate response, particularly in terms of the Atlantic meridional overturning circulation (AMOC) and the Southern Ocean. Recent developments in scale-aware parameterisations of the mesoscale are being developed and will be included in future Earth System models.

Summary Although the choice of ocean resolution in Earth System models will always be limited by computational considerations, for the foreseeable future, this choice is likely to affect projections of climate variability and change as well as other aspects of the Earth System. Future Earth System models will be able to choose increased ocean resolution and/or improved parameterisation of processes to capture physical processes with greater fidelity.

HTH, EB, PM, PH, MJR, and MB acknowledge the Met Office Hadley Centre Climate Programme. MJR, DP, and TA acknowledge PRIMAVERA funding received from the European Commission under Grant Agreement 641727 of the Horizon 2020 research programme. EP, TK, and AY were supported by the National Environmental Research Council (NERC) National Capability Science Multi-Centre funding for the UK Earth System Modelling project through grant NE/N018036/1 and the EU Horizon 2020 CRESCENDO project, grant number 641816. BFK is supported by ONR N00014-17-1-2963, NSF 1350795 and 1655221, and NOAA NA19OAR4310366. RB was supported by NSF’s Southern Ocean Carbon and Climate Observations and Modeling (SOCCOM) Project under NSF Award PLR-1425989. DPM is supported by NERC NE/R000999/1. TA acknowledges PRACE for awarding us access to MN4 supercomputer, hosted by BSC, Spain. The CESM1.3 simulations are completed through the International Laboratory for High Resolution Earth System Prediction (iHESP)—a collaboration among QNLM, TAMU, and NCAR, from which QZ, BG, and FC acknowledge funding. LZ was supported by NSF‐GEO 1912357 and NOAA CVP NA19OAR4310364.

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