*INTERFACE:*

subroutine do_kpp(nlev,h0,h,rho,u,v,NN,NNT,NNS,SS,u_taus,u_taub, & tFlux,btFlux,sFlux,bsFlux,tRad,bRad,f)

Here, the time step for the KPP model is managed. If `kpp_interior=.true.`
in `kpp.nml`, the mixing algorithm for the computation of the interior
diffusivities is called first. This algorithm is described in section 4.35.3.
Then, if `kpp_sbl=.true.` and `kpp_bbl=.true.`, the algorithms
for the surface and bottom boundary layer are called. They are described in
section 4.35.4 and section 4.35.5, respectively.

If this routine is called from a three-dimensional code, it is essential to
pass the correct arguments. The first 3 parameters relate to the numerical
grid, discussed in section 3.1.2. Note that `h0` denotes
the local bathymetry, i.e. the positive distance between the reference level
and the bottom.

The next three parameters denote the potential density, , and the two mean velocity components, and . The buoyancy frequency, , and the different contributions to it, and , have to be computed from the potential density as discussed in section 3.14. The shear frequency, , is defined in (36). The vertical discretisation does not necessarly have to follow (39), since in the KPP model no TKE equation is solved and thus energy conservation is not an issue. All three-dimensional fields have to be interpolated "in a smart way" to the water column defined by GOTM. The corresponding interpolation schemes may be quite different for the different staggered grids, finite volume, and finite element approaches used in the horizontal. Therefore, we cannot offer a general recipe here.

The bottom friction velocity is computed as described in section 3.9. If this parameter is passed from a three-dimensional code, it has to be insured that the parameter in (24) is computed consistently, see (25).

All fluxes without exception are counted positive, if they enter the water body. Note that for consistency, the equations of state in GOTM cannot be used if the KPP routines are called from a 3-D model. Therefore, it is necessary to pass the temperature and salinity fluxes, as well as the corresponding buoyancy fluxes. The same applies to the radiative fluxes. The user is responsible for performing the flux conversions in the correct way. To get an idea have a look at section 8.10.

The last argument is the Coriolis parameter, . It is only used for clippling the mixing depth at the Ekman depth.

*USES:*

IMPLICIT NONE

number of grid cells integer :: nlev bathymetry (m) REALTYPE :: h0 thickness of grid cells (m) REALTYPE :: h(0:nlev) potential density at grid centers (kg/m^3) REALTYPE :: rho(0:nlev) velocity components at grid centers (m/s) REALTYPE :: u(0:nlev),v(0:nlev) square of buoyancy frequency (1/s^2) REALTYPE :: NN(0:nlev) square of buoyancy frequency caused by temperature and salinity stratification REALTYPE :: NNT(0:nlev),NNS(0:nlev) square of shear frequency (1/s^2) REALTYPE :: SS(0:nlev) surface and bottom friction velocities (m/s) REALTYPE :: u_taus,u_taub surface temperature flux (K m/s) and salinity flux (psu m/s) (negative for loss) REALTYPE :: tFlux,sFlux surface buoyancy fluxes (m^2/s^3) due to heat and salinity fluxes REALTYPE :: btFlux,bsFlux radiative flux [ I(z)/(rho Cp) ] (K m/s) and associated buoyancy flux (m^2/s^3) REALTYPE :: tRad(0:nlev),bRad(0:nlev) Coriolis parameter (rad/s) REALTYPE :: f

Original author(s): Lars Umlauf

Karsten Bolding 2012-12-28