[MITgcm-support] Set a density distribution

[fancer fancer]

Hi, guys.

One more question about density and buoyancy.
I've find in the source code the next formulas:
*find_rho.f:*

...
refTemp=tRef(kRef)
refSalt=sRef(kRef)
dRho = rhoNil-rhoConst
...
rhoLoc(i,j) = rhoNil*(sBeta*(sFld(i,j)-refSalt) - tAlpha*(tFld(i,j)-refTemp)
) + dRho
...

*calc_buoyance.f*

...
buoy(i,j) = -gravity*recip_rhoConst*rholoc(i,j)
...

*ini_parms.F*

...
recip_rhoConst = 1. _d 0 / rhoConst
...

I don't set tRef, therefore refTemp = 0.0.
I set sBeta = 0.0, rhoNil = rhoConst = 1000.0, therefore dRho = 0.0.
Now I get:
rhoLoc = - rhoNil*tAlpha*tFld(i,j)
buoy(i,j) = -gravity*recip_rhoConst*rholoc(i,j)

What's wrong in my calculations? Or may be something wrong in source code.
Is rhoLoc a density or something other?
I've found the next mailing-list:
http://mitgcm.org/pipermail/mitgcm-support/2006-December/004492.html
And I am sure that density should be:

rhoLoc(i,j) = rhoNil*(*1 + *sBeta*(sFld(i,j)-refSalt) -
tAlpha*(tFld(i,j)-refTemp) ) + dRho

Could you please answer me where I wrong?

Sincerely,
Serge Semin

On Tue, Apr 19, 2011 at 11:22 PM, fancer fancer <fancer.lancer at gmail.com>wrote:

> Matt, Ryan
>
> Thanks you very much.
> This is a very useful approach for me! Now I testing it.
>
> Good luck you in your researches.
> Sincerely,
> Serge Semin
>
>
> On Tue, Apr 19, 2011 at 1:45 AM, Ryan Abernathey <rpa at mit.edu> wrote:
>
>> Serge,
>>
>> What Matt described is what many of us do in idealized setups where we
>> don't care about T & S individually but only about buoyancy in general.
>> Specifically, I use the following options in my data file.
>>
>> eosType='LINEAR',
>> tAlpha=2.0E-04,
>> sBeta=0.,
>> saltStepping = .false.,
>>
>> Then the buoyancy is defined as
>> gravity * tAlpha * THETA
>>
>> You can set an initial buoyancy just by setting an initial temperature. In
>> your data file, this would look like
>>  &PARM05
>>  hydrogThetaFile='myHydrogThetaFile.bin',
>>  &
>>
>> -Ryan
>>
>> On Apr 18, 2011, at 5:35 PM, Matthew Mazloff wrote:
>>
>> Hi Serge,
>>
>> You cannot just set density -- as you stated, T and S are the state
>> variables used by the MITgcm.  If you are running an idealized experiment,
>> however, you can just turn off salinity stepping (saltStepping = .false., in
>> data PARM01)  and just use T making your equation of state linear such that
>> T and rho will be analogous.
>>
>> -Matt
>>
>>
>> On Apr 18, 2011, at 2:06 PM, fancer fancer wrote:
>>
>> Matt,
>>
>> I mean dynamics density, but for initial conditions.
>> I mean can I set a matrix with 3D density profile of my area, instead of
>> setting T and S at initial time?
>> If I understand your answer properly, I can not.
>> I looked the equations of model and understood what it is impossible.
>> Every time calculates T and S  through the special equations. Then density
>> calculates through EOS and desity goes to equation of motion.
>> MITgcm do not have a equation for  evolution of density. But if it has, it
>> can be possible. Right?
>>
>> Sincerely,
>> Serge Semin
>>
>>
>> On Tue, Apr 19, 2011 at 12:34 AM, Matthew Mazloff <mmazloff at ucsd.edu>wrote:
>>
>>> Hi Serge,
>>>
>>> Do you mean reference density or dynamics density.
>>>
>>> Dynamic density is not  a model input, but instead calculated from T and
>>> S using one of the equation of state (EOS) options.  Some of the EOS have
>>> matlab equivalents in
>>> http://mitgcm.org/viewvc/MITgcm/MITgcm/utils/matlab/
>>>
>>> Reference density is taken as a constant, and should not be spatially
>>> varying....
>>>
>>> -Matt
>>>
>>>
>>>
>>> On Apr 18, 2011, at 12:18 PM, fancer fancer wrote:
>>>
>>> Hi, MITgcm support.
>>>
>>> How can I set a density distribution for my computational area?
>>> I know about rhoRefFile input parameter, but this is a 1D vector, where
>>> each element for one vertical layer.
>>> I have a 3D matrix with density profile for my area.
>>> Is there are some special input parameters or method for integrating it
>>> into computational area?
>>>
>>> In advance thanks for help.
>>>
>>> Sincerely,
>>> Serge Semin
>>> <ATT00001.txt>
>>>
>>>
>>>
>>> _______________________________________________
>>> MITgcm-support mailing list
>>> MITgcm-support at mitgcm.org
>>> http://mitgcm.org/mailman/listinfo/mitgcm-support
>>>
>>>
>> <ATT00001.txt>
>>
>>
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>>
>>
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