[MITgcm-support] C grid and pressure

[Nicolas Grisouard]

Hi everyone,

Allow me to follow up on a discussion I started 6 months ago.

On 1/7/12 11:37 AM, Jean-Michel Campin wrote:
> Hi Nicolas,
>
> [...] the pressure P can be obtained as:
> P(i,j,k)/rhoConst = -g*rC(k) + PH(i,j,k) + PNH(i,j,k)
>
> And PHL would be the equivalent of PH (hydrostatic pressure potential anomaly)
> but at the bottom, so that the hydrostatic pressure at the bottom Pb
> would be: Pb(i,j)/rhoConst = g*Depth(i,j) + PHL(i,j)

And what about the full bottom pressure? I am trying to compute the 
force acting on a topography, so I want to integrate something like 
P*h', where P is the pressure and h'is the topographic slope. The way I 
compute P is (following the previous notations):

Pb(i,j)/rhoConst = g*Depth(i,j) + PHL(i,j) + PNHbott(i,j),


where I created PNHbott by locating the lowermost cells with some water 
in them and picking up the value of PNH there. I guess my worry is that 
I am doing something with the PNH fields that was not supposed to be 
allowed with the PH fields. Am I?

The actual numbers tell that the g*Depth(i,j) term dwarfs the other 
ones, but not enough when integrated against h' to completely ignore the 
pressure anomalies.

Thank you for your time and help,
Nico.

-- 
Nicolas Grisouard -- Assistant Research Scientist
Courant Institute of Mathematical Sciences
251 Mercer Street -- New York, NY 10012-1185
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