[MITgcm-support] Regional high-res model configuration

[Stanislav Martyanov]

Hello, dear colleagues!

I am configuring the MITgcm for the Kara Sea region. With the* curvilinear
grid*, the model's resolution is: *dx=500-1200 m, dz=2 m* in upper layers,
and up to* 20 m* in the deepest. The minimum model depth is set equal to *5
m*. I use the *pure r* vertical coordinate (not *r**) for now. Because of
the curvilinear grid, I use *vectorinvariant* package. Other packages used
are: *seaice, my82, exf, cal, obcs*.

Having carefully read (once again) the newest version of the online-manual
and browsed the code, I have configured almost all necessary model
parameters, but still some questions remain. They are qiute specialized, so
I could not find the needed information in puplished papers. But for those
experienced with MITgcm, they might be easy to answer. I will appreciate
any advise!

1) The newly added feature with partial cells (#undef *EXCLUDE_PCELL_MIX_CODE
in CPP_OPTIONS*). The parameter *pCellMix_select = 0* by default, which
means that the enhanced mixing is OFF in bottom and surface layers. The
parameters intended for the enhanced mixing in the inner layers are also
OFF by default: *interViscAr_pCell* and *interDiffKr_pCell = FALSE*. Are
this option and the corresponding run-time parameters really important for
such configuration (Kara Sea)? Any experience with them?

2) I use the following viscocity and diffusivity values, intending to use
the *Smagorinsky viscocity* for lateral turbulent exchange:






*viscAh = 1.0, viscC2smag = 3.0, viscAr = 1.0e-5, diffKhT = 1.0, diffKhS=
1.0, diffKrT = 1.0e-5, diffKrS = 1.0e-5*,
But for diffusivity there is no *Smagorinsky* analogue. What approach can
be the most suitable in this case?

3) In the paper "*ECCO version 4 - an integrated framework... " by Forget
et al., 2015*, the authors decided to switch OFF the *C-D sheme* and to
switch ON the *Implicit vertical advection* option. But they investigated
the global scales, not high-res. From your experience, can their advise be
applyed to the high-res ocean simulations?

4) The *MY82* package does not allow using the convective adjustment (
*cAdjFreq*) and *ivdc_kappa*. Does it mean that the MY in MITgcm works fine
with vertical instability cases? Actually, it should, as follows from J.
Mellor's papers, but this question arose when I was investigating the
*GGL90* code, where I found the line "*convective adjustment might be
needed even with ggl90*"...

Once again, I will appreciate any advise!

PS: Sorry for large wall-of-text here, but I tried to be concrete. :-)
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