[MITgcm-support] what's the difference between U, V, W, salt in data.diagnostic and the output result

[Martin Losch]

Chunyan,

the diagnostics package already has a long list of predefined diagnostics. With each run of the model you'll get this list (taylored to the specific configuration) in "available_diagnostics.log". I'd check with this file before implementing anything new. For example (from this file):
   142 |UBotDrag| 50 |   143 |UUR     MR|m/s^2           |U momentum tendency from Bottom Drag
   143 |VBotDrag| 50 |   142 |VVR     MR|m/s^2           |V momentum tendency from Bottom Drag
That might already do what you want.
If you cannot find a diagnostic, you can define your own by using one of the S/UDIAGS (at the beginning of the file). E.g. add 'SDIAG9 ' and 'SDIAG10' (because they are defined at U/V points) to the list of diagnostics and then "fill" then at the appropriate place in the code by calling diagnostics_fill (see also <http://mitgcm.org/public/r2_manual/latest/online_documents/node266.html>)
You can also define new names by editing diagnostics_main_init , just copy a similar block, eg. for oceTAUX/Y and edit. You do not need to edit diagnostics_addtolist.F (There is no more diagnostics_add2list and the documentation is a little out of date)

M.


On Mar 24, 2011, at 6:13 PM, Chun-Yan Zhou wrote:

> Dear Martin,
>  Thanks for your help. I have tried as you suggested and can reproduce U,V,W with diagnostics package.
>  And if I want to add a new 2D array such as bottom shear stress which is calculated from velocity, and want to output it. I suppose it can be done through data.diagnostic, because its structure just like ETAN. And I know that I have to modify the diagnostics_add2list, but I can't understand well. Is there any examples?
>  Many thanks!
>  chunyan
> ----------------------------------------------------------------------
> 
> Message: 1
> Date: Thu, 24 Mar 2011 16:32:35 +0100
> From: Martin Losch <Martin.Losch at awi.de>
> To: mitgcm-support at mitgcm.org
> Subject: Re: [MITgcm-support] what's the difference between U, V, W,
> salt in data.diagnostic and the output result
> Message-ID: <839AE782-F849-46C2-B52E-42498078C55F at awi.de>
> Content-Type: text/plain; CHARSET=US-ASCII
> 
> Hi,
> 
> the values in the dynDiag file are averages, with the averagin period specified by this line:
> frequency(2) = 864000.,
> to 10-day averages, while the other output (either in state.*.nc or in the *.data/meta files) are snapshots (frequency is controlled by dumpFreq in "data"). To reproduce this with diagnostics package you need to use a negative frequency (to get snapshots) and also a non-default "output phase" (by default the output is at the center of teh interval, so for frequency(2)=-864000., the first output would be after 5 days, the second after 10, etc). I think that timePhase(2) = 864000., would do the job, but please check with documentation.
> 
> btw, uvelmass is u*hfacw, and vvelmass is v*hfacs
> 
> Martin
> 
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