[MITgcm-support] Non-Hydrostatic Energy Budget

[钱钰坤]

Hi Bertrand,


I tried to close the momentum/energy budget using MITgcm one year ago and
suffered a lot as you.  So I write two notebooks and collect all the information
I can find.  You may find them useful:
https://github.com/miniufo/notebooks/blob/master/Budget%20in%20MITgcm%20Part%20III.ipynb
https://github.com/miniufo/notebooks/blob/master/Budget%20in%20MITgcm%20Part%20IV.ipynb


However, I did not remember any clue on close w-momentum budget in
nonhydrostatic case.  Maybe you are the first one trying to do it.


On energy budget, you are right that you have to take the dot product of
velocity vector and momentum equations.  I remember that there is a major
change of the diagnostic package that some diagnostics have been re-grouped
to simplified the budget (you can find this in the reference part of the notebook).
So you have to make sure the version of the model that contains the change or
not.




------------------

 Best regards 
 
Yu-Kun Qian (钱钰坤) 
Center for Monsoon and Environment Research 
 Department of Atmospheric Sciences
School of Environmental Science and Engineering 
 Sun Yat-sen University 
No. 135 Xingang West Road, Haizhu District 
Guangzhou, 510275, P.R. China 
Tel; 020-84115227 
Email: qianyk at mail3.sysu.edu.cn      


 
 
 
------------------ 原始邮件 ------------------
发件人: "Bertrand Delorme"<bdelorme at stanford.edu>;
发送时间: 2020年11月24日(星期二) 晚上9:31
收件人: "mitgcm-support at mitgcm.org"<mitgcm-support at mitgcm.org>; 

主题: Re: [MITgcm-support] Non-Hydrostatic Energy Budget

 

  
Hi everyone,
 
 
 
Follow-up to my previous post below. It seems that the diagnostics Wm_Advec, Wm_Diss and AB_gW are available with the code in NH mode. However, to have a complete budget, I would need the total  vertical pressure gradient (something like a Wm_dPhiZ diagnostic). It would also be nice to have the tendency of the vertical velocity (something like TOTWTEND). I can’t find any of these two diagnostics in  the code of the model. Is there a reason why those haven’t been included with the other diagnostics of the vertical momentum equation? Is there any ways to access them outside of an offline calculation?
 
 
 
Thank you,
 
 
 
Bertrand
 
 
  
De : Bertrand DELORME <bdelorme at stanford.edu>
 Date : vendredi 13 novembre 2020 à 16:24
 À : "mitgcm-support at mitgcm.org" <mitgcm-support at mitgcm.org>
 Objet : Non-Hydrostatic Momentum Budget
 
  
 
 
 
Hi everyone,
 
 
 
I am trying to compute the fully non-hydrostatic energy budget of my internal wave simulation using the Diagnostics package and I have a few questions:
 
 
 
 i)                    I read that the diagnostics Um_Advec and Vm_Advec already contain the Coriolis terms. Does that mean that in NH mode, Um_Advec contains both the -f*v and +fh*w, where f is the vertical component  of the Coriolis parameter and fh the horizontal component of the Coriolis parameter? When calculating the energy budget, one needs to take the dot product of the momentum equations with the velocity vector, effectively canceling out the Coriolis terms in the  energy equation. However, using only the horizontal momentum equations diagnostics (i.e.,  Um_Advec and Vm_Advec), we don’t get the -fh*u term coming from the vertical momentum equation that permits to cancel out the +fh*w term from the zonal momentum equation.  Is that really what is happening when we perform U . Um_Advec + V . Vm_Advec (i.e., we get a u*fh*w term that is not balanced)? If yes, is there a way to get a Wm_Advec term from the diagnostics package or do I have to calculate it offline when performing  my energy budget?
 
 
 
 ii)                   In a previous post from Jean-Michel, I read that the surface pressure horizontal gradient needs to be added to the Um_dPHdx and Vm_dPHdy diagnostics. However, when I run my simulation, I don’t  get the Um_dPHdx and Vm_dPHdy diagnostics but I get the Um_dPhiX and Vm_dPhiY diagnostics instead, which seem to already incorporate the surface pressure gradient. Am I right on that? Also, do these new diagnostics incorporate the NH pressure field?
 
 
 
Thank you,
 
 
 
Bertrand Delorme
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