[MITgcm-support] [EXTERNAL] Seaice water drag

[Kalyan Shrestha]

Hi Ou,

I forgot to mention in my previous post that there is no atmospheric
forcing in all the three experiments. This is just a spindown problem of a
mixed layer front.

Thanks,
Kalyan

On Wed, May 13, 2020 at 9:52 AM Wang, Ou (US 329B) <ou.wang at jpl.nasa.gov>
wrote:

> Kalyan,
>
>
>
> Do the three experiments have atmospheric forcing? If so, isn’t in Case A
> the ocean will feel the wind stress and other atmospheric forcing directly
> since there is no sea-ice (sea-ice concentration c=0), while Cases B and C
> don’t because the ocean is fully covered by sea-ice (c=1).
>
>
>
> I don’t have an explanation why Cases B and C have exactly similar
> results. They should be somewhat different.
>
>
>
> Regards,
>
> Ou
>
>
>
> *From: *MITgcm-support <mitgcm-support-bounces at mitgcm.org> on behalf of
> Kalyan Shrestha <kalyansh at uw.edu>
> *Reply-To: *"mitgcm-support at mitgcm.org" <mitgcm-support at mitgcm.org>
> *Date: *Wednesday, May 13, 2020 at 9:28 AM
> *To: *"mitgcm-support at mitgcm.org" <mitgcm-support at mitgcm.org>
> *Subject: *[EXTERNAL] [MITgcm-support] Seaice water drag
>
>
>
> Hello everyone,
>
>
>
> I am trying to explore baroclinic instability under sea ice. However, in
> the MITgcm sea ice model, I noticed that changing the drag doesn't seem to
> affect anything, which means that there is something weird happening with
> the sea ice-water drag. Let me elaborate this with an example - please
> refer the related figure in the dropbox link below.
>
> *https://www.dropbox.com/s/ipcnf2p95w00itp/SeaiceWaterDrag.pdf?dl=0
> <https://www.dropbox.com/s/ipcnf2p95w00itp/SeaiceWaterDrag.pdf?dl=0>*
>
>
>
> For this, I have designed three numerical experiments, which are
> as follows. The only difference in the following three cases is in sea ice
> concentration and sea ice water drag, while all other parameters are
> identical.
>
> Case A-- sea ice concentration, c =0; and Sea ice-water drag, Cd = 5.35E-03
>
> Case B-- c = 1; Cd = 0
>
> Case C-- c = 1; Cd = 1.32E-03
>
>
>
> Physically, Case A and Case B should give the same result because both
> have zero sea ice-water stress. On the other hand, Case B and Case C should
> behave differently as their drag coefficients have changed. However, the
> results are surprising. Contrary to what is expected, Case A and Case B
> give unidentical results, whereas Case B and Case C give exactly similar
> results. Apart from total kinetic energy vs time plot and salinity contours
> in the attached figure, I also checked the energetics and other
> diagnostics, and the results do not make physical sense.
>
>
>
> Could you please help me to understand this?
>
>
>
> Thanks,
>
> Kalyan Shrestha
>
>
>
>
>
>
>
>
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