[ecco-support] [EXTERNAL] surface pressure in LLC4320

[Dimitris Menemenlis]

Hi Matt, yes you are correct.
The equivalent sea level assuming all snow and ice is melted would be:
SSH = ETA + sIceLoad / rhoConst
sIceLoad = SIheff * SEAICE_rhoIce + SIhsnow * SEAICE_rhoSnow
SEAICE_rhoIce = 910
SEAICE_rhoSnow = 330
rhoConst = 1027.5

Depending on application, you may want to remove tides and atmospheric
pressure.  There is two ways to do that.  One is to compute steric height
from Theta and Salt.  That means you need full 3D fields.  A second way is:
steric = SSS - PhiBot - AtmosPres
where PhiBot is bottom pressure and AtmosPres surface atmospheric
pressure, including tidal-potential forcing.  This second way is accurate
to within accuracy of model’s inverse barometer adjustment.
Jinbo has done a more complete analysis of accuracy of above two methods
that I can try to dig up, if it is needed.

D.


> On Oct 20, 2020, at 9:53 AM, Matthew Mazloff <mmazloff at ucsd.edu> wrote:
> 
> Hello 
> 
> We love the LLC4320 - thank you!
> 
> We are analyzing the SO dynamics in it, and we need to know surface pressure. However ETAN appears to be the water column height under the sea ice. Is this correct - do we need to add sea ice loading?
> 
> If so would it be 
>            sIceLoad  = HEFF * SEAICE_rhoIce + HSNOW * SEAICE_rhoSnow
> And then 
> 	phiSurf = ( etan + sIceLoad*recip_rhoConst ) *gravity
> 
> Much appreciated!
> Matt
> 
> 
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