[MITgcm-devel] switching seaice_obcs from legacy to devel

[Menemenlis, Dimitris (3248)]

Sounds good. I agree. I will go ahead and check in later today.

I am trying to remember if An's experiment warmed or cooled with new code. This behavior would certainly explain a warming with newer code and we would need to readjust albedos accordingly.

Wish I was in Cambridge with u guys.

Dimitris Menemenlis

On Dec 15, 2012, at 8:46 AM, "Martin Losch" <Martin.Losch at awi.de> wrote:

> Hi Dimitris,
> 
> sitting vis a vis with Jean-Michel at his kitchen table, here's my (really: our) take on this:
> 1. we don't want to use the legacy code anymore and in fact most (all) of us don't, so it's better to test the code that is being used.
> 2. having very small ice thicknesses (10e-3) with 100% does not appear very physical, so searching for this would mean searching for a problem in code that we actually want to get rid off.
> 
> So let's go ahead and use the non-legacy code in this experiment without further worrying about the differences.
> 
> Martin
> 
> On Dec 15, 2012, at 12:41 AM, "Menemenlis, Dimitris (3248)" <Dimitris.Menemenlis at jpl.nasa.gov> wrote:
> 
>> Dear MITgcm sea ice developers, as requested I am working on switching
>> verification/seaice_obcs from legacy to devel code.
>> 
>> With #undef SEAICE_GROWTH_LEGACY
>> I get some rather large differences in the output of the 3 experiments:
>> 
>> Y Y Y Y> 2< 2  7  5  5  5  9  7  4  1  1  2  2 16  2  3  2  0  2  0  0  0  4  3  3 FAIL  seaice_obcs
>> Y Y Y Y> 2< 2  7  5  4  5  9  7  4  1  1  3  2 16  1  3  2  0  2  0  0  0  3  3  3 FAIL  seaice_obcs.seaiceSponge
>> Y Y Y Y> 3< 2  7  5  5  5 10  7  4  2  1  3  3  1  3  3  3  0  2  0  0  0  4  3  3 FAIL  seaice_obcs.tides
>> 
>> I have traced this difference back to large differences in "AREA" between legacy and devel branches.
>> In attached figure I plot AREA, HEFF, and Qsw after 6 model time steps for the legacy
>> and devel branches an for the difference.
>> Note that in region of very thin ice (lower right quadrant of panels),
>> the legacy code gives ~100% ice cover, while the devel code give ~0% ice cover.
>> This has big consequence for shortwave radiation.
>> 
>> I have following questions:
>> 
>> - Do you know what is causing this difference?
>> 
>> - Are there compile-time or run-time flag options that can reduce this difference?
>> 
>> - Shall we just check in the new output.txt as is?
>>  For the things that are being tested in seaice_obcs, this difference is probably not important,
>>  and the devel treatment is probably more realistic in terms of shortwave forcing.
>> 
>> Dimitris Menemenlis
>> 
>> <legacy.jpeg>
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> 
> 
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