Scale-awareness in an eddy energy constrained mesoscale eddy parameterization

Journal article

There is an increasing interest in mesoscale eddy parameterizations that are scale-aware, normally interpreted to mean that a parameterization does not require parameter recalibration as the model resolution changes. Here we examine whether Gent–McWilliams (GM) based version of GEOMETRIC, a mesoscale eddy parameterization that is constrained by a parameterized eddy energy budget, is scale-aware in its energetics. It is generally known that GM-based schemes severely damp out explicit eddies, so the parameterized component would be expected to dominate across resolutions, and we might expect a negative answer to the question of energetic scale-awareness. A consideration of why GM-based schemes damp out explicit eddies leads a suggestion for what we term a splitting procedure: a definition of a “large-scale” field is sought, and the eddy-induced velocity from the GM-scheme is computed from and acts only on the large-scale field, allowing explicit and parameterized components to co-exist. Within the context of an idealized re-entrant channel model of the Southern Ocean, evidence is provided that the GM-based version of GEOMETRIC is scale-aware in the energetics as long as we employ a splitting procedure. The splitting procedure also leads to an improved representation of mean states without detrimental effects on the explicit eddy motions.

Authors: Mak, J; Maddison, JR; Marshall, DP; Ruan, X; Wang, Y

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: American Geophysical Union
• Journal: Journal of Advances in Modeling Earth Systems
• Volume: 15
• Issue: 12
• Article number: e2023MS003886
• Publication date: 2023-12-19
• Acceptance date: 2023-10-27
• DOI: 10.1029/2023MS003886
• EISSN: 1942-2466
• Language: English
• Subjects: eddy, parameterization, ocean modeling, scale-aware, energetics