[MITgcm-support] C grid and pressure

[Nicolas Grisouard]

Hi everyone,

Two simple questions, they should be easy but I'm having a hard time 
confirming my guesses.

1/ In the pdf of the MITgcm manual, if you take a look at figure 2.9 
(the one showing the 3D staggering of velocity components), you see that 
w is evaluated on top and bottom of a tracer cell. So if you have Nr 
tracer cells, you should get Nr+1 vertical points for the W field, which 
is not the case. Does it mean that the bottom point is systematically 
ignored as is it zero? And hence that the z-coordinate for the W field 
is RF minus its bottom point?

2/ I am running oceanic, non-hydrostatic configurations with a linear 
free surface (nonlinFreeSurf = 0) and linear EOS. If I want to have the 
pressure at a given point i,j,k located in the center of a tracer cell, 
do I need to simply do the following:

P(i,j,k) = PH(i,j,k) + PNH(i,j,k) + Eta(i,j)*g*rho_surface(i,j) ?

PH, PNH and Eta are the result of reading the output files of the same 
names and rho_surface will be diagnosed from the temperature. What about 
PHL in the presence of topography? After searching through the 
documentation as well as the support list archive, I finally managed to 
get completely confused on that issue.

Thanks for your time and help,
Nicolas.

-- 
Nicolas Grisouard
Assistant Research Scientist
Courant Institute of mathematical Sciences
251 Mercer Street
New York, NY 10012
tel: (+1) 212-992-9920 -- room 927
Office Skype ID: nicolas.grisouard
http://nicolas.grisouard.free.fr