Will High-Resolution Global Ocean Models Benefit Coupled Predictions on Short-Range to Climate Timescales?
This is a review article of the benefits of the explicit resolution of mesoscale eddies, narrow boundary currents and their frontal structures, and topographic-flow interactions in the ocean components of global coupled models. Based on published, albeit limited results, the emerging consensus is that the realistic representation of these features and processes is important for coupled prediction.
Fine resolution coupled models allow for the representation of climate processes and feedbacks on short space scales that are currently missing in standard coupled models. Overall both ocean and atmospheric circulations are impacted by the presence of explicit mesoscale eddies and well-resolved frontal systems.
A review of published findings indicates that it is very likely important to explicitly resolve oceanic mesoscale eddies, frontal systems associated with western boundary currents, and topographic-flow interactions in coupled prediction models. In standard climate models, these processes and features are either unrealistically represented or are parameterized, or may even be missing. It was found that explicitly resolved mesoscale eddies reduce subsurface ocean model warming drifts, improving the realism of water masses relative to those in standard models. The energy cycle and meandering state of the Kuroshio Extension in the North Pacific was found to be strongly dependent on mesoscale eddy-atmosphere feedbacks. Accurate simulation of climate change responses in the Southern Ocean was reported to be critically dependent on mesoscale eddies. Mesoscale oceanic eddies impact the atmospheric boundary layer and above, as well as extra-tropical storm tracks. In the Gulf Stream region, storm track biases were reduced and blocking frequencies improved.