Detailed Description

By Robert Hallberg, 2015.

This file contains the subroutine (energetic_PBL) that uses an integrated boundary layer energy budget (like a bulk- or refined- bulk mixed layer scheme), but instead of homogenizing this model calculates a finite diffusivity and viscosity, which in this regard is conceptually similar to what is done with KPP or various two-equation closures. However, the scheme that is implemented here has the big advantage that is entirely implicit, but is simple enough that it requires only a single vertical pass to determine the diffusivity. The development of bulk mixed layer models stems from the work of various people, as described in the review paper by Niiler and Kraus (1979). The work here draws in with particular on the form for TKE decay proposed by Oberhuber (JPO, 1993, 808-829), with an extension to a refined bulk mixed layer as described in Hallberg (Aha Huliko'a, 2003). The physical processes portrayed in this subroutine include convectively driven mixing and mechanically driven mixing. Unlike boundary-layer mixing, stratified shear mixing is not a one-directional turbulent process, and it is dealt with elsewhere in the MOM6 code within the module MOM_kappa_shear.F90. It is assumed that the heat, mass, and salt fluxes have been applied elsewhere, but that their implications for the integrated TKE budget have been captured in an array that is provided as an argument to this subroutine. This is a full 3-d array due to the effects of penetrating shortwave radiation.