부산대학교 도서관

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. Plain Language Summary: With increasing computational power, ocean models are starting to explicitly resolve eddy motions with characteristic length‐scales of 10–100 km. With the increased model resolution, there is an increasing call for scale‐aware parameterizations, that is, simplified models that are supposed to represent the missing eddy feedbacks onto the modeled state that are either self‐tuning, or do not require re‐tuning of parameters, without damping explicit eddies resolved by the model. The question we ask is whether an eddy parameterization known as GEOMETRIC is scale‐aware. The expected answer might be "no": such schemes are known to heavily flatten density variations and damp out explicitly resolved eddies. We instead propose a splitting scheme that avoids damping of explicitly resolved eddies. The GEOMETRIC scheme, with the use of splitting, seems to be scale‐aware in the sense that there is approximate constancy of total eddy energy, where the explicit and parameterized components vary with resolution, and additionally lead to other desirable features in the model considered. Key Points: Evidence is presented for scale‐awareness of the GEOMETRIC eddy parameterization with a "splitting" approachScale‐awareness means constancy of total eddy energy, while the explicit and parameterized components vary with resolutionIn eddy permitting calculations, such eddy parameterizations should be applied to the large‐scale background state, obtained via "splitting" [ABSTRACT FROM AUTHOR]