[MITgcm-devel] Add sea ice surface forcing to pkg/seaice

[Jean-Michel Campin]

Hi Dimitris,

I think I already answered this by writing the following:
> Point (iii) to (v) are even more confusing to me.

Fine with me to stay with the code as it is now, as long as:
a) things are clear (clarification below).
b) I can put the "snowprecipFile" business into the list of
  "other reason to use pkg/thsice (instead of pkg/seaice thermo)"
c) we don't turn on snowprecipFile in experiment global_ocean.cs32x15 
  (input.seaice + ad tests).

clarification:
1) we know how to implement snowPrecip, whether it's specified
  through snowprecipFile or inferred for precip & atemp/tsurf
  (cf pkg/thsice).
2) however a different route has been taken in seaice_growth.F
  in order to squeeze in ice from iceberg into snow precip.

Note regarding point (2): by thsice standard, it would be called a bug, 
but in pkg/seaice, it's not so clear according to your list of 
remarks from yesterday, (i) to (v), which left me confused.

Cheers,
Jean-Michel

On Mon, Apr 23, 2012 at 11:25:44PM +0000, Menemenlis, Dimitris (3248) wrote:
> Jean-Michel, to address your concerns below and in previous two messages,
> (and make sure that novice telemarkers will not be overwhelmed by too much fresh powder)
> 
> I can set AREA=1 when and where following conditions are met:
> snowPrecipFile .NE. ' '
> snowPrecip(i,j,bi,bj) .GT. ZERO
> HSNOW .GT. siEps
> or some slightly more adjoint-friendly version of above.
> 
> The assumption is that snowPrecip spreads evenly in each model grid box where it is non-zero.
> 
> Will that be OK?
> 
> Dimitris Menemenlis
> 
> On Apr 23, 2012, at 3:50 PM, Jean-Michel Campin wrote:
> 
> > Dimitris,
> > 
> > I am confused about your comments (i) to (v) below.
> > For me, the actual snow thickness is more natural that 
> > the effective one. Can do in-situ measurements. 
> > If it does not exist in some parts of seaice_growth but still exists
> > in seaice_solve4temp, it's going to be quite chalenging to explain 
> > to new users how seaice pkg works.
> > Point (iii) to (v) are even more confusing to me.
> > 
> > But to come back to my example of a good snow fall (> 1.cm/h) over 
> > small fraction of seaice, which could be as low as 10^-5 for default
> > SEAICE_area_reg=siEPS, within the same grid cell, the SST can 
> > still be warm enough to be cooled by the latent heat of the snow 
> > and to remain above freezing (no new ice formed). But instead of 
> > doing this, the falling snow will increase the actual snow thickness 
> > over seaice at a rate ~10^5 larger than the real accumulation rate.
> > Can easily get 1.km of fresh snow (ye, fresh powder !) in an hour or so.
> > 
> > Cheers,
> > Jean-Michel
> 
> 
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