[MITgcm-support] get info Momentum/Vorticity Budget

[Martin Losch]

Marco,

I really suggest that you keep this thread on support-list, even if no-one other than me answers. Did you read the post by Emily in the link? It also contains instructions (further down in the thread) how to derive the viscosity contribution from the diagnostics variable VISrI_Um:

>  Um_Impl(:,:,k) =[ VISrI_Um(:,:,k+1) - VISrI_Um(:,:,k) ]
>                 /[ rAw(:,:)*drF(k)*hFacW(:,:,k) ]
>  (hope I got the sign right)
> 
>  VISrI_Um(k=1) should be zero, and the bottom one (k=Nr+1) is not shored in the output file but it’s also zero.

The same should be true for your explicit contribution VISrE_Um. I would also save VISrI_U/Vm just to make sure that they are really zero.

Martin



> On Nov 30, 2013, at 7:25 PM, Marco Reale <reale.marco82 at gmail.com> wrote:

> Hi Martin,
> 
> Thanks for the forward of my mail to MITGCM support list.Unfortunately I didn’t get any answer so far…What it looks strange  to me are the strong difference in term of magnitude among all the values. I mean at t=100 in a point of my grid :
> 
> Totutend/86400=2.150995812742083e-10
> 
>      Um_Advec=-5.585041762401488e-08
>      VISrE_Um =-1.181081396934272e-10
>      Um_Corios=-5.584458406815429e-08
>>> Um_Diss= -9.438065884381786e-10
>>> Um_dPHdx=-9.924201016531242e-09
>>> Um_Ext=0
>>> dEta/dx=-1.075985166033507e-08
> 
>      Utend(sum of previous terms)=-1.334409690971671e-07
> 
> I have the rigid lid and my fields(included Totutend) are not snapshot but average over 432000 (frequency positive in the file data.diagnostics).all the terms are output from the model except Utend (my summation) and Dtheta/dx(computing as (Etan(i+1)-Etan(i))/DXC(i)..Am I doing something wrong in summing? about the sign of Deta/dx?Should I multiply it for gravity acceleration?Should I divide/multiply my terms for something else?should i simply sum  them or considering difference signs in the summation?
> 
> Cheers
> 
> Marco
> 
> 
> 
> 
> 
> 
> Il giorno 28/nov/2013, alle ore 13:46, Martin Losch <Martin.Losch at awi.de> ha scritto:
> 
>> Hi Marco,
>> 
>> I am returning this to the support list. There is no guarantee that I (or any individual) can answer a specific question so it is better to have more listeners. I am sorry you haven’t got a satisfactory reply so far.
>> 
>> Here’s an email thread that ends with success (I found it by entering this: “totutend site:mitgcm.org/pipermail” in google.com, I don’t understand why “our” search function does not work properly, that’s an continous problem):
>> 
>> http://mitgcm.org/pipermail/mitgcm-support/2010-December/006921.html
>> 
>> Apparently, you need to include surface elevation gradient (d ETAN / d x).
>> 
>> Martin
>> 
>> On Nov 28, 2013, at 12:43 PM, Marco Reale <reale.marco82 at gmail.com> wrote:
>> 
>>> Dear dr. Losch,
>>> 
>>> My name is Marco and I’m ph.d Student in Environmental and Industrial Fluid Mechanics at University of Trieste.Presently I’m involved in a joint project between OGS and ICTP.I’m using the model MITGCM to study the upper layer variability of circulation of Ionian Sea. Now I’m computing  vorticity and momentum budget for the Ionian Sea using the diagnostics coming from the model.In the file data.diagnostics I set frequency(n)=432000  and I got the following diagnostics :  totutend, Um_Diss,Um_Advec,Um_Cori,Um_dPHdx,Um_Ext,VISrE_Um (I’m using explicit scheme).I didn’t consider the rigid lid in the computations. Similar diagnostics have been got for totvtend,Then I applied the formula for each time step dr Campin suggests in MITGCM mailing list
>>> 
>>> “TOTUTEND/86400=Um_Diss+Um_Advec+Um_Cori+Um_dPHdx+Um_Ext"
>>> 
>>> but it doesn’t work. The difference appears to be strong  (two or three orders of magnitude).
>>> 
>>> Then I applied the curl in the form MITGCM uses for computing relative vorticity to each previous term of momentum budget and compared the final result with Z3 coming from the model but also in this case the difference is strong(an overestimation of 20%)…
>>> 
>>> In the past I wrote to MITGCM list but I didn’t get any suggestion or advice.Could you provide some suggestions or advice?
>>> 
>>> Looking forward to a positive response to my reply
>>> 
>>> Best regards
>>> 
>>> Marco
>>> ***********************************
>>> Marco Reale
>>> ph.D student "Environmental and Industrial Fluid Mechanics"-XXVII cycle
>>> University of Trieste-Department of Mathematics and Informatics
>>> National Institute of Geophysics and Oceanography (OGS)
>>> International Center for Theorethical Physics (ICTP)
>>> Italian Geophysical Association
>>> Italian Meteorological Society
>>> web-page: http://phdfluidmechanics.appspot.com/stud.html?Reale
>>> skype: mcreal82
>>> phone number: +39 3270888069
>>> 
>>> ***********************************
>>> 
>> 
> 
> ***********************************
> Marco Reale
> ph.D student "Environmental and Industrial Fluid Mechanics"-XXVII cycle
> University of Trieste-Department of Mathematics and Informatics
> National Institute of Geophysics and Oceanography (OGS)
> International Center for Theorethical Physics (ICTP)
> Italian Geophysical Association
> Italian Meteorological Society
> web-page: http://phdfluidmechanics.appspot.com/stud.html?Reale
> skype: mcreal82
> phone number: +39 3270888069
> 
> ***********************************
>