[MITgcm-support] convertEmP2rUnit

[Jean-Michel Campin]

Hi Martin, 

I think that convertEmP2rUnit should be:
 convertEmP2rUnit = rhoConstFresh*recip_rhoConst*horiVertRatio
and not: 
 =1. [if ocean-Z] 
 =rhoConstFresh*Gravity [if ocean-P]
as it is now.

The result is the same for ocean-P since horiVertRatio=rhoConst*Gravity
in this case (and horiVertRatio=1 in ocean-Z).

My point is: 
if we think that a different rhoConst for Fresh water
is needed in the ocean-P, then it seems logical to have the
same ability in ocean-Z. 

The reason why I ask this is that I started to use rhoConstFresh 
for the density of the fresh water with sea-ice component
and with atmospheric model, and cannot reach a perfect 
conservation unless I set rhoConstFresh=rhoConst, simply because
presently convertEmP2rUnit=1. whatever rhoConstFresh/rhoConst is.

What do you think ?

Jean-Michel