KPP

[rafferrari]

I wonder whether we can recast the Ri number criterion in KPP in terms of an energy argument. I am thinking something along the lines described in Reichel and Hallberg for ePBL. The idea is that the increase in mixed layer depth Delta h must be such that the potential energy gained is equal to the turbulent kinetic energy generated by buoyancy fluxes or mechanical stresses. The formula looks a lot like a bulk Ri criterion.

[glwagner]

That sounds like formulating an equation for the rate of change of h --- in other words, a prognostic ODE for h? That seems like a nice idea to me, actually; it certainly seems more robust than the bulk criterion that is currently used.

I'm not too familiar with Kraus-Turner but I think that model involves a prognostic equation for h? Should we think about coding up Kraus-Turner in OceanTurb.jl, and then pursuing a hybrid KT-KPP model?

[rafferrari]

I think the ePBL paper nicely summarizes the prognostic equation for w_e, i.e. the rate of deepening of the mixed layer. The basic idea is to write the potential energy + kinetic energy budget, assuming that fluxes are linear function of z, so that the vertical integrals are easy to compute. I wonder whether one can relax the assumption of linear vertical fluxes in a model that resolves the vertical structure of the mixed layer, like KPP, but still use the energy budget to infer the rate of deepening of the mixed layer.