[MITgcm-support] calculate total pressure

[钱钰坤]

Hi all,


I have read some threads on how to calculate total pressure in this maillist like:
http://mailman.mitgcm.org/pipermail/mitgcm-support/2013-August/008448.html
http://mailman.mitgcm.org/pipermail/mitgcm-support/2013-November/008636.html
but I still got some related questions.


My case here is hydrostatic.  I concluded that the total pressure potential would be:
p(k, j, i)/rhoConst = PHrefC(k) + PHIHYD(k, j, i) = g*rC + PHIHYD(k, j, i)
1) Why not adding ETAN*g or PHI_SURF?  I notice that surface contribution should be
take into account when one needs to close the momentum budget.


2) There is a slightly difference between ETAN*g and PHI_SURF when using implicit free-
surface (http://mailman.mitgcm.org/pipermail/mitgcm-devel/2019-March/007065.html).
Does this difference matter here if surface contribution should be taken into account?


3) I found that ETAN(j, i)*g is quite similar to PHIHYD(0, j, i) at the first level.  Is there any
relationship between the two? or just because they are very close to each other (my first
tracer level is defined at -2.5m depth).


4) I found that the bottom pressure should be calculated as:
p_bot(j, i)/rhoConst = g*Depth + PHIBOT(j, i)
So I would expect that p_bot(j, i) >= p(k, j, i).  Is this correct?

My MITgcm is c66g and I noticed that the pressure diagnostics may be re-grouped
in the recent version (including surface contribution in PHIHYD?).  So I hope I am
doing this calculation correctly.


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

 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      


 
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