[MITgcm-devel] pkg/icefront

[Dimitris Menemenlis]

Hi Martin, the vertical faces are needed for Greenland glaciers, which often terminate and calve at the grounding line, i.e., that have no ice shelf cavity beneath them.

My preference is for a separate package because

(i) rather than search 2D space for ice shelf cavities, the icefront package needs to search a 3D space for the ice fronts,

(ii) probably best to save position of the ice fronts in vectors during initialization in the same way as is done in pkg/downslope,

(iii)  each grid box can have up to three separate contributions from ice fronts while ice shelf cavities only have one contribution from the top,

(iv) shelfice_thermodynamics.F can be rewritten using the downslope formulation (and also shelfice_u_drag.F and shelfice_v_drag.F I think) but they would be radically different and harder to read than they are right now,

(v) eventually the physics of the two packages may diverge to include different processes, for example, a fancier boundary layer scheme for shelfice and a calving scheme for icefront, and

(vi) it's less coding effort to separate the two packages.

I will proceed with a separate package.  OK?

D.

On Dec 9, 2009, at 11:42 PM, Martin Losch wrote:

> Without having thought about this too much I think you should extend  
> pkg/shelfice.
> But: I only neglected the horizontal faces, because it was simpler and  
> nobody so far cared about them: dx = 5km and larger, dz = 10m-500m ->  
> area of ice front/area of ice base = 1/10 at maximum (and even this  
> only hypothetically at very large depths, because normally the ice  
> shelves extend to 1500m, where the vertical resolution is better than  
> 500m in ECCO/ECCO2 and any other configuration that I can think of),  
> more like 1/100 - 1/500. Is it really worth it? The entire  
> parameterization is so shaky that add another 1% of uncertainty  
> doesn't really seem to matter, does it?