[MITgcm-support] Problems about the diagnostic output of MITgcm

[Martin Losch]

Hi Yaoxuan,

(1) for the pure advective fluxes (3 components, one for each grid direction) use ADVx_Vm, ADVy_Vm, ADVrE_Vm, and the same for Um (only for fluxform, I’m afraid). Vm_Advec includes the total tendency (i.e. also Coriolis). The metric terms, however, stem from the representation of the advection on a non-cartesian grid, right? I agree that the description of this diagnostic is misleading. You could always substract the Coriolis term (Vm_Cori).

(2) “PHI_NH  “ gives you “Non-hydrostatic Pressure Pot.(p/rho)”, that’s what you want. (check the list of “available_diagnostics.log” that should contain this variable if you are really using the non-hydrostatic cde.

(3) I suggest that you use one of the verification experiments, e.g. isomip/input.htd as an example (they do have non-zero SHIfwFlx if you set the corresponding “frequency” to a small number, e.g. 1). Try also ‘SHIForcS’

Martin

> On 5. Sep 2019, at 22:42, 曾耀萱 <yxzeng at pku.edu.cn> wrote:
> 
> Hi everyone,
> 
> 
> I am now doing ocean simulations on MITgcm with shelfice package, non-hydrostatic settings and flux-form momentum equations. Now I have some problems with the diagnostic output:
> 
> 
> (1) For the advection term Um/Vm_Advec, the description is "U/V momentum tendency from Advection terms", but I checked the pkg/mom_fluxform/mom_fluxform.F and find that it may be wrong:
> 
> Line 950, the diagnostic output is filled by gV: 
> 
>         CALL DIAGNOSTICS_FILL(gV(1-OLx,1-OLy,k,bi,bj),
>      &                               'Vm_Advec',k,1,2,bi,bj,myThid)
> Before that, gV is added by advection terms (line 689), metric terms (line 867 and 876) and Coriolis terms (line 907), so it seems that the final output should be advection terms + metric terms + Coriolis terms.
> 
> 
> (2) I also want to know how I can get the output of the non-hydrostatic pressure field (phi_NH) in the model.
> 
> 
> (3) For the Ice shelf freshwater flux (SHIfwFlx), I get the output of all zeros, which is quite weird because there is salinity change so the ice should be melting/freezing. I'm not sure if this is caused by some settings for the shelfice package. My data.shelfice settings are as follows:
> 
> 
>  &SHELFICE_PARM01
>  SHELFICEboundaryLayer = .FALSE.,
>  SHELFICEtopoFile='ice.topo',
>  SHELFICEloadAnomalyFile = 'p.anomaly',
>  useISOMIPTD = .FALSE.,
>  SHELFICEconserve = .TRUE.,
>  SHELFICEuseGammaFrict = .FALSE.,
>  no_slip_shelfice = .false.,
>  SHELFICEwriteState = .TRUE.,
>  SHELFICEthetaSurface = -81.2,
>  rhoShelfIce = 926.,
>  SHELFICEsaltTransCoeff = 4.E-8,
>  SHELFICEheatTransCoeff = 7.E-7,
>  &
> 
> 
> Thanks,
> 
> Yaoxuan
> 
> 
> 
> 
> 
> 
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