Abstract:

The representation of ocean mesoscale eddies (analogous to mid-latitude atmospheric storms) presents a formidable theoretical and computational challenge in ocean global circulation models. At present ocean mesoscale eddies are often not explicitly resolved in models (including those involved contributing to the IPCC reports through the CMIP exercises) due to computation cost, at least not over the high latitudes and the Southern Ocean, and eddy effects are often parameterised. Increasingly however the emergent ocean climatology and its sensitivity between eddy resolving and eddy parameterising models have been found to diverge, in turn impacting model properties such as ocean ventilation time scales, heat content, and so forth. A new geometrically informed, energetically constrained parameterisation is presented, which predicts and demonstrates eddy saturation and degrees of eddy compensation, and in turn on ocean heat content. The rather counter-intuitive role of eddy energy dissipation in setting global ocean stratification and ocean heat content is discussed.

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(Host faculty: Prof. Yan WANG)