[MITgcm-support] NLFS=4 with z coordinates.. and sea ice

[Daniel Goldberg]

thanks J-M! i didn't know about the sIceLoadFac parameter either, so that will be an option.

best
dan
________________________________
From: MITgcm-support <mitgcm-support-bounces at mitgcm.org> on behalf of Jean-Michel Campin <jmc at mit.edu>
Sent: Tuesday, September 22, 2026 13:18
To: mitgcm-support at mitgcm.org <mitgcm-support at mitgcm.org>
Subject: Re: [MITgcm-support] NLFS=4 with z coordinates.. and sea ice

Hi Dan,

It should work, not used much without z*, precisely for the reason you mentioned,
see also the Ocean modelling paper, doi:10.1016/j.ocemod.2008.05.005 :
"Sea ice-ocean coupling using a rescaled vertical coordinate z*"

Note that you could always bring back an inconsistent "levitating" sea ice with
a recently added param (in "data", first namelist): sIceLoadFac=0.,

Cheers,
Jean-Michel

On Tue, Sep 22, 2026 at 11:18:26AM +0000, Daniel Goldberg wrote:
> Hello!
>
> I am curious if anyone has used nonlinear free surface (NLFS=4) with z-coordinates and with the sea ice model?
>
> I suspect that it will be limited by the thickness of the top cell relative to the sea ice thickness, and am prepared to deal with surf_adjustment errors if they occur.
>
> But aside from this, Im wondering if there are any numerics/packages that simply won't work, of if i will get a RT error simply for trying this combination of parameters?
>
> Thanks!
> dan
>
> --
> Daniel Goldberg, PhD (he/him)
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