New GLS routine (for verticals physics)

[rbourdal]

A new zdfgls.F90 routine has been implemented at Mercator Ocean.
Find in this ticket this new routine and the namelist bloc associated (namelist_ref should be changed !)
the namzdf_gls is tune for k-epsilon closure.

!-----------------------------------------------------------------------
&namzdf_gls ! GLS vertical diffusion ("key_zdfgls")
!-----------------------------------------------------------------------

rn_emin = 1.e-6 ! minimum value of e [m2/s2]
rn_epsmin = 1.e-12 ! minimum value of eps [m2/s3]
ln_length_lim = .true. ! limit on the dissipation rate under stable stratification (Galperin et al., 1988)
rn_clim_galp = 0.267 ! galperin limit
ln_sigpsi = .true. ! Activate or not Burchard 2001 mods on psi schmidt number in the wb case
rn_crban = 100. ! Craig and Banner 1994 constant for wb tke flux
rn_charn = 70000. ! Charnock constant for wb induced roughness length
rn_hsro = 0.02 ! Minimum surface roughness
rn_frac_hs = 1.3 ! Fraction of wave height as roughness (if nn_z0_met=2)
nn_z0_met = 2 ! Method for surface roughness computation (0/1/2)
nn_bc_surf = 1 ! surface condition (0/1=Dir/Neum?)
nn_bc_bot = 1 ! bottom condition (0/1=Dir/Neum?)
nn_stab_func = 2 ! stability function (0=Galp, 1= KC94, 2=CanutoA, 3=CanutoB)
nn_clos = 1 ! predefined closure type (0=MY82, 1=k-eps, 2=k-w, 3=Gen)

/
!-----------------------------------------------------------------------

[rbourdal]

This new routine has been used in the GMD paper (G. Reffray et al., 2014: ​http://www.geosci-model-dev.net/8/69/2015/gmd-8-69-2015.pdf).
The default value of rn_emin has been changed from 1e-6 to 1e-7 m2.s-2 in namelist_ref. The diffusivities and viscosities values are then closed to those obtained with tke model below the mixed layer. The values in the mixed layer are not impacted.

The AMM12 namelist_cfg has been modified to conserve the same physical choice for the surface rugosity computation.

https://forge.ipsl.jussieu.fr/nemo/changeset/5109/trunk