[MITgcm-devel] pkg/seaice wish list

[Patrick Heimbach]

Hi there,

On Jun 11, 2007, at 8:31 AM, chris hill wrote:

> Hi Martin,
>
>  A break - I'm shocked!

It seems to wear down even the strongest! ;o)

>  What is the status of the documentation/paper on the seaice?  
> Patrick and I would be happy (actually I haven't checked this with  
> Patrick!)

Chris, you owe me a huge (sea-)ice cream for that one :o)

> to spend a bit of time trying to get the technical documentation up  
> to date in the manual. If you have anything we can start from that  
> would be good.

Agree.
-p.

PS:
We should aim to have a documentation before the Arctic sea-ice is  
all gone:
Stroeve, J., M. M. Holland, W. Meier, T. Scambos, and M. Serreze. 2007.
Arctic sea ice decline: Faster than forecast. Geophysical Research  
Letters 34, L09501



> Chris
> Martin Losch wrote:
>> Hi,
>> after all these changes during the last week(s), I would like to  
>> take a break from this seaice frenzy, but not without writing down  
>> a few thing that still require some attention, technically speaking:
>> 1. Defaults: currently, the seaice ice package has a few  
>> unfortunate defaults (they affect only seaice_growth and  
>> seaice_advdiff and not the dynamics):
>> - SEAICEadvSnow = .false. (changing this will change lab_sea again)
>> - flooding should probably be turned on by defaut (currently  
>> #undef ALLOW_SEAICE_FLOODING and SEAICE_flooding = .false., I  
>> suggest removeing the CPP-flag, if TAF complies, and setting  
>> SEAICE_flooding = .true., (also changes lab_sea)
>> - #undef SEAICE_MULTICATEGORY should probably turned on by  
>> default. That's a standard feature of ice models (modifies lab_sea)
>> - comment in these as default in seaice_growth:
>> CML#ifdef SEAICE_EXTERNAL_FORCING
>> CMLC     this seems to be more natural as we do compute the wind  
>> speed in
>> CMLC     pkg/exf/exf_wind.F, but it changes the results
>> CML          UG(I,J) = MAX(SEAICE_EPS,wspeed(I,J,bi,bj))
>> CML#else
>> [...]
>> CML#endif
>> 2. time stepping variables: I would like to get rid of these 3  
>> time levels for HEFF, AREA, UICE/VICE. They make life miserable  
>> and increase the number of exchange unnecessarily. But this would  
>> also mean that the B-grid code would be really out of date and  
>> unusable (unless that is sorted out as well). It also means that  
>> advection with leap-frog is no longer possible (currently it's  
>> only possible with the default advection scheme = 2 and no  
>> advection of snow, so that's not really a loss)
>> 3. related to 2: sort out the pickup files. We don't need all time  
>> levels in the pick up files (in fact we need only one) and we  
>> don't need all of these variables in there, e.g. YNEG could  
>> definitely be a local variable in seaice_growth. the pickup could  
>> be devided into a dynamics and a thermodynamics pickup, since we  
>> only need the dynamics, if we want to use seaice+thsice.
>> This way we could also have netcdf pickups more easily (possibly).
>> 4. sort out spurious exchanges especially in seaice_model
>> 5. remove the spurious seaice forcing "package" (along with some  
>> diagnostics, e.g. UWIND/VWIND)
>> 6. Improve vectorisation of seaice_lsr/evp
>> 7. add some sanity test (as Chris has suggested earlier). I have  
>> two tests for the dynamics only, one is based on Hunke, JCP  
>> (2001), maybe in the contrib area?
>> 8. add simple and exchangable/tunable ridging algorithms (in a  
>> transparent way, not as it is done now in seaice_growth, and who- 
>> knows-where in thsice).
>> 9. Finally, find a way to give the MITgcm a more transparent way  
>> of doing sea ice: that is, either merge seaice and thsice (which I  
>> prefer) or separate seaice into a dynamics and a thermodynamics  
>> package
>> ... anything else? Oh yes, documentation, coming soon (o:
>> Martin
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>
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---
Dr Patrick Heimbach | heimbach at mit.edu | http://www.mit.edu/~heimbach
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