[MITgcm-support] changes in seaice default behaviour?

[Martin Losch]

Hi Christoph,

here:
<https://github.com/MITgcm/MITgcm/issues/107>
you can see, what the new defaults are. I guess you can try to do override some of them:

SEAICEscaleSurfStress (was .FALSE. now .TRUE.)
SEAICEaddSnowMass (was .FALSE. now .TRUE.)
SEAICE_useMultDimSnow (was .FALSE. now .TRUE., this will make ice thicker)
SEAICE_drag (factor of two smaller now)
SEAICE_waterDrag (shouldn’t make too much of a difference, since you didn’t set it explicitly)

More precise comments in doc/tag-index

I’m afraid, that none of this seems to me to be a candidate for your problems (maybe scaleSurfStress).

Martin

> On 31. Jan 2019, at 16:17, Christoph Voelker <christoph.voelker at awi.de> wrote:
> 
> Dear all,
> 
> I have problems in continuing a global ocean run for the last glacial maximum that I suspect are related to changes in the default behaviour of the seaice module in checkpoint 67d.
> 
> I used to run the model with the somewhat outdated version checkpoint 66f over 3000 years. Then I switched to the newer code version, recompiled and wanted to continue the run for another 1000 years or so. What then happens is that - without having changed anything in my data.seaice and SEAICE_OPTIONS.h - the model starts accumulating very thick ice around Antarctica; ice tends to build up to typical ice thicknesses of more that 15 m where I previously only had 2 m or so. Eventually the model crashes and I believe it has to do with seaice+snow reaching a thickness of more than 60m in a few points.
> 
> Can anyone perhaps tell me which of the new defaults in the seaice parameters might me responsible and suggest what I could change?
> 
> I must add to this that I run a scenario where I force the model with atmospheric output (temperature, winds etc) from a coupled ocean atmosphere climate model run for the last glacial, so I get rather cold air temperatures around Antarctica. For that reason my data.seaice has already a few settings to prevent a too strong seaice buildup:
> 
> # SEAICE parameters
>  &SEAICE_PARM01
>   SEAICEwriteState   = .TRUE.,
>   SEAICE_initialHEFF = 0.0,
>   HO = 1.,
>   SEAICEuseFlooding = .true.,
>   SEAICEadvSnow     = .true.,
>   SEAICEpressreplfac = 0.,
>   SEAICE_clipVelocities = .false.,
>   SEAICEadvScheme   = 33,
>   SEAICE_no_slip    = .false.,
> # SEAICE_deltaTevp  = 360.,
>  &
> 
> Cheers, Christoph
> 
> -- 
> Christoph Voelker
> Alfred Wegener Institute
> Helmholtz Centre for Polar and Marine Research
> Am Handelshafen 12
> 27570 Bremerhaven, Germany
> e: Christoph.Voelker at awi.de
> t: +49 471 4831 1848
> 
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