[MITgcm-support] GMRedi ptracers Diagnostics

[Martin Losch]

Hi Dhruv,

Hong pointed out to me, that I was wrong: it is possible to specify 3D GM and Redi diffusivities. There are parameters in the gmredi namelist (GM_background_K3dFile, GM_isopycK3dFile), but the code for reading the fields is connected to the ctrl-package. The corresponding 5d-fields KapGM and and KapRedi are defined in pkg/ctrl/CTRL_FIELDS.h, so that they are only available when the control package is compiled (set in pacackage.config) and the CPP-flags ALLOW_KAPGM_CONTROL, ALLOW_KAPREDI_CONTROL are defined.

There is probably a good reason for doing this in this way, but I am not quite sure if I can suggest how you want use this information. Either you compile the ctrl-package (which will require that you add a definition of nobcs into SIZE.h, please example SIZE.h in the verification/*/code_ad/ directories) and define the cpp flags and keep your fingers crossed, or you take the definition of fields out of the ctrl package and put them into the GMREDI-header file and adjust ini_mixing and/or gmredi_init_varia.F (where I would have put reading the fields in the first place, but then again, since they have been meant for ecco-type optimization, there is probably a good reason for doing it they way it has been done).

Maybe others have an opinion on this?

Martin

> On 19. Oct 2018, at 15:55, Martin Losch <Martin.Losch at awi.de> wrote:
> 
> Hi Dhruv,
> 
>> On 19. Oct 2018, at 03:21, Dhruv Balwada <db194 at nyu.edu> wrote:
>> 
>> Hi, 
>> 
>> I am running a MITgcm channel simulation in coarse resolution with the GMRedi package, forced with winds and buoyancy at the surface. I also advect tracers using the ptracers package. 
>> I have 2 questions:
>> a) Is it possible to provide MITgcm with an arbitrary 3D GM diffusivity and a 3D Redi diffusivity field as input, in the current MITgcm release? If 3D fields cannot be specified, then is it possible to provide a vector with the depth variation? I am interested in prescribing arbitrary fields, rather than a particular diffusivity parameterization scheme.
> 
> I don’t think so, you can only specify 3D fields of vertical diffusivies, afaik.
>> 
>> b) When the model is being run with both GMRedi and ptracers packages, what is the  flux diagnostic for the ptracer tracer that has the influence of the GMRedi diffusion tensor? 
> Don’t the normal diffusive flux diagnostics should contain this (DFxETr01, DFyETr01, DFrETr01, DFrITr01, etc.)?
> 
> Martin
>> 
>> Thank you,
>> Dhruv
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>