[MITgcm-devel] SHELFICEBoundaryLayer ustar calculation with hFacC>1

[Daniel Goldberg]

Thanks for pointing this other one out, Martin. Not sure we want that
behavior (with drLoc<0) for the forcing either..

For now, I propose a quick fix to revert to non-shelficeboundarylayer
behaviour for shelfice_forcing.F when hfacC(kTopC)>1, by setting drLoc=0 in
this case. (This will mean that if hFacC(kTopC)>>1, then shelfice
temperature and salinity forcing will have a smaller effect, but we are
trying to limit how large hFacC becomes as the shelf thins..)

Would these changes be OK to check in:
http://mitgcm.org/viewvc/MITgcm/MITgcm_contrib/dgoldberg/shelfice/shelfice_thermodynamics.F?revision=1.2&view=markup
(see
line 283)

http://mitgcm.org/viewvc/MITgcm/MITgcm_contrib/dgoldberg/shelfice/shelfice_forcing.F?revision=1.1&view=markup
(see
lines 78, 86, 170, 178)

Thanks
Dan

On Tue, Apr 21, 2015 at 7:43 AM, Martin Losch <Martin.Losch at awi.de> wrote:

> Hi Dan,
>
> clearly, this code was written with hFac<=1 in mind. I think your limiting
> drKp1 from below makes absolute sense, because this scheme was only meant
> to work for hFac<1, and as you can see from the code, the largest effect is
> larger the smaller hFacC is. For a fully wet cell, it should do anything.
> There are two more occurence of this in shelfice_forcing (there the
> variable is drLoc).
>
> M.
> > On 18 Apr 2015, at 21:56, Daniel Goldberg <dngoldberg at gmail.com> wrote:
> >
> > Hi Martin
> >
> > At the moment we are using ShelficeBoundaryLayer for the calculation of
> melt rates, but are allowing hFacC to be larger than 1.
> >
> > But we find this allows the factor drKp1 to become negative (line 280 of
> shelfice_thermodynamics.F) and velocities from the cell below even when the
> top cell is thicker than drF(kTopC).
> >
> > Is this correct, or was this written with only hFacC(kTopC)<1 in mind?
> At the moment we are simply inserting the line
> >
> > drKp1 = MAX(drKp1, 0.0)
> >
> > after line 282 (although long term we hope to implement something like
> what J-M has suggested, using wet-point averaging to find ustar at the
> center of the cell).
> >
> > Many thanks
> > Dan
> >
> >
> >
> > --
> >
> > Daniel Goldberg, PhD
> > Lecturer in Glaciology
> > School of Geosciences, University of Edinburgh
> > Geography Building, Drummond Street, Edinburgh EH8 9XP
> >
> >
> > em: Dan.Goldberg at ed.ac.uk
> > web: http://ocean.mit.edu/~dgoldberg
> > _______________________________________________
> > MITgcm-devel mailing list
> > MITgcm-devel at mitgcm.org
> > http://mitgcm.org/mailman/listinfo/mitgcm-devel
>
>
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-- 

Daniel Goldberg, PhD
Lecturer in Glaciology
School of Geosciences, University of Edinburgh
Geography Building, Drummond Street, Edinburgh EH8 9XP


em: D <dgoldber at mit.edu>an.Goldberg at ed.ac.uk
web: http://ocean.mit.edu/~dgoldberg
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