[MITgcm-devel] horiVertRatio in forcing

[Jean-Michel Campin]

Hi Chris,

> I don't get it :-)
> 
> When r->p we define our coordinate system as (m,m,pa) so volume has units
> m*m*pa
> When r->m we define our coordinate system as (m,m,m ) so volume has units
> m*m*m
> 
> So it is the mass per unit volume in our coordinate system - isn't it?
> 
> Chris

Yes.

It happens that the forcing is generally defined 
relatively to unit of mass. So the most usefull conversion factor
for the forcing is from mass to model volume unit (m^3 if z, m^2.pa if p).
I like to have the "r" in rVolume because, as Alistair wrote, it's not the
physical volume unit but the "model" volume unit, that is the units
of dx.dy.dr. 
This does not include the thickness of the surface
level and will not be function of k. This is consistent with
the boussinesq formulation of the z model (rVolume2mass=rhoConst). 
In the p model (hydrostatic, nonboussinesq) there is no need to have 
a rhoConst, and rVolume2mass=1/gravity (since dr=dp=g*(rho*dz) ).

I am not going to change anything right now, not until every one agree.

See you,

Jean-Michel