[MITgcm-devel] seaice adjoint and EVP
Martin Losch
Martin.Losch at awi.de
Wed May 23 10:03:12 EDT 2007
Hi,
I would like to include the zMin = 0 fix before updating the adjoint
results. Interestingly this change changes results of lab_sea
dramatically, I don't quite see why, but I would like to hear
Dimitris opinion about this first.
Martin
On 23 May 2007, at 15:40, Patrick Heimbach wrote:
>
> There's setups in
> verification/lab_sea/code_ad_seaice_only/
> .../code_ad_ocean_only/
>
> They will need updating after all the recent months' changes,
> but shouldn't be too hard.
>
> -p.
>
>
>
> On May 23, 2007, at 8:28 AM, chris hill wrote:
>
>> Martim, Jean-Michel, Patrick etc...,
>>
>> It would really nice to be able to run the sea-ice calculations
>> in a controlled "offline" mode. This would help do sanity checks
>> on forward and reverse sea-ice. It would also then be
>> straightforward to make comparisons with scheisse :-). Are we in a
>> position to do that or are there still some exf, sea-ice, thsice,
>> bulkf etc... issues outstanding?
>>
>> Chris
>> Martin Losch wrote:
>>> Hi Jinlun,
>>> the evp-solver is only in place for the C-grid. I don't have the
>>> time to code the solver for the b-grid now. The b-grid code (for
>>> LSR) is still working, but I have not kept it up to date, so
>>> there may be a few thing different other than the different grids.
>>> In general I though that the c-grid is perfect for evp as all the
>>> discretizations fall in place naturally. Only for this \delta
>>> term one needs to average from center to corner points and vice
>>> versa (have a look at seaice_calc_strainrates and seaice_evp).
>>> However, there may be issues with the coriolis terms (commonly a
>>> problem with the c-grid).
>>> Actually, Elizabeth told us that she masks ice velocities over
>>> open water in CICE.
>>> Now we are a little stuck, aren't we?
>>> Martin
>>> PS. I need to be able to reproduce these results myself (I
>>> haven't been able to, yet), maybe I can debug the stuff this way.
>>> Via email etc. it's quite demanding (o:
>>> On 21 May 2007, at 19:15, Jinlun Zhang wrote:
>>>> I wouldn't think C-grid is problematic with EVP as we have seen.
>>>> But just to make sure, is it possible to use the original B-grid
>>>> EVP to see if the same things occur? There was a B-grid ice
>>>> model setup in place that may be used for doing B-grid.
>>>> Better not zap out things over open ocean. Otherwise,
>>>> discontinuity may occur and ocean may be screwed up.
>>>> Jinlun
>>>>
>>>>>> Hi Martin,
>>>>>>
>>>>>>> 1. Are these figures all with with zMin = 0?
>>>>>>
>>>>> In this case it may be worth turning of individual terms in the
>>>>> rhs of the momentum equations
>>>>> 1. dphiSurf/dx and dphiSurf/dy (in seaice_dynsolver)
>>>>> 2. surface wind stress (taux/y=0 in seaice_get_dynforcing)
>>>>> 3. ice-ocean stress (DWATN in seaice_evp)
>>>>> 4. Coriolis
>>>>> 5. stressDivergence
>>>>> 4 and 5 should be zero over open ocean anyway so I do not see
>>>>> how these terms can lead to the stripes.
>>>>> We should get to the bottom of what is causing these stripes.
>>>>> that way we can probably understand the noise in the ice
>>>>> fields, too.
>>>>>
>>>>>>
>>>>>> Yes, all the figures and results under
>>>>>> http://ecco2.jpl.nasa.gov/data1/arctic/output/tests/
>>>>>> (except for the oldtest subdirectory) are with zMin=0.
>>>>>>
>>>>>>> 2. Do you have an EVP run that does not blow up at all
>>>>>>> (regardless of noise)?
>>>>>>
>>>>>> I have not run any of the zMin=0/SEAICEuseFlooding=.true.
>>>>>> tests out for very
>>>>>> long, but I am almost certain that none of these new
>>>>>> integrations will crash,
>>>>>> including the SEAICE_deltaTevp=60.
>>>>>> The crashes had to do with snow accumulation and could happen
>>>>>> to both LSR or to
>>>>>> EVP solutions.
>>>>>
>>>>> That's good news. It mean that we can (in principle) maskRHS
>>>>> flag and not worry about the stripes.
>>>>>
>>>>>>
>>>>>>> 3. What's the convergence criterion for LSR, and how many
>>>>>>> interations do you allow/do? In other words how close is the
>>>>>>> LSR solution to VP?
>>>>>>
>>>>>>
>>>>>> LSR_ERROR = 2e-4,
>>>>>> SOLV_MAX_ITERS=1500
>>>>>
>>>>> That's not very much, is it? For an accurate VP solution I
>>>>> would put LSR_ERROR = 1e-7 to 1e-13, right?
>>>>>
>>>>>>
>>>>>>> c. the same is true for the wind-ice/ocean-ice stress terms
>>>>>>> which in involve
>>>>>>> averaging perpendicular to the stripes (unless the turning
>>>>>>> angle is not
>>>>>>> equal to zero, in which case there is also averaging in the
>>>>>>> other directions,
>>>>>>> but you don't do that, do you?).
>>>>>>
>>>>>>
>>>>>> No I use SEAICE_airTurnAngle=SEAICE_waterTurnAngle=0.
>>>>>
>>>>> Good.
>>>>>
>>>>>>
>>>>>>> About question 3 (is it really a VP solution): Could you
>>>>>>> diagnose SIsigI and SIsigII (snapshots!!!! I guess one is
>>>>>>> enough) for all (or some) solutions and
>>>>>>> plot them (plot(SIsigII(:),SIsigI(:),'x')? These should be
>>>>>>> the principle components of sigma normalized by the strength/
>>>>>>> pressure P.
>>>>>>
>>>>>>
>>>>>> With SEAICE_dumpFreq, SIGMA1, SIGMA2, and SIGMA12 are
>>>>>> diagnosed by default for
>>>>>> the EVP solutions but not for LSR. Are these the same as
>>>>>> SIsigI and SIsigII?
>>>>>> Figure for SIGMA1, SIGMA2 for EVP solution is here:
>>>>>> http://ecco2.jpl.nasa.gov/data1/arctic/output/tests/figs/
>>>>>> SIGMA2232.ps
>>>>>> Does it look as expected?
>>>>>
>>>>> sigma1/2/12 are not the principle stress components. I have
>>>>> added diagnostics that are called SIsigI and SIsigII, which is
>>>>> what you want. In principle you could computed them yourself
>>>>> (from snapshots):
>>>>> SIsigI = 0.5*(sigma1 + sqrt(sigma2^2 + 4*sigma12^2)/Press
>>>>> SIsigII = 0.5*(sigma1 - sqrt(sigma2^2 + 4*sigma12^2)/Press
>>>>>
>>>>> Press = max(1.e-13,Pstar * HEFF *exp( -20*(1-AREA)));
>>>>>
>>>>> see seaice_do_diags.F (and seaice_dynsolver.F)
>>>>>
>>>>>>
>>>>>>> I am also a little concerned that the LSR and EVP solutions
>>>>>>> look so different
>>>>>>> in the ice-covered area, can that be attributed to that
>>>>>>> different boundary
>>>>>>> conditons? Can you try a run with no slip for the evp solver?
>>>>>>
>>>>>>
>>>>>> Is LSR no slip by default? How do you specify no slip for evp
>>>>>> solver?
>>>>>
>>>>> LSR is half slip and that's hardwired. I didn't want to bother
>>>>> this the boundary conditions if EVP works, because it's so
>>>>> much simpler to do that in EVP. But now I may have to
>>>>> reconsider this decision.
>>>>> EVP is free slip by default. SEAICE_no_slip = .true. makes it
>>>>> no slip.
>>>>>
>>>>> Martin
>>>>>
>>>>> _______________________________________________
>>>>> MITgcm-devel mailing list
>>>>> MITgcm-devel at mitgcm.org
>>>>> http://mitgcm.org/mailman/listinfo/mitgcm-devel
>>>>
>>>>
>>>> --
>>>> Jinlun Zhang
>>>> Polar Science Center, Applied Physics Laboratory
>>>> University of Washington, 1013 NE 40th St, Seattle, WA 98105-6698
>>>>
>>>> Phone: (206)-543-5569; Fax: (206)-616-3142
>>>> zhang at apl.washington.edu
>>>> http://psc.apl.washington.edu/pscweb2002/Staff/zhang/zhang.html
>>>>
>>>>
>>>>
>>>>
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> ---
> Dr Patrick Heimbach | heimbach at mit.edu | http://www.mit.edu/~heimbach
> MIT | EAPS, 54-1518 | 77 Massachusetts Ave | Cambridge, MA 02139, USA
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