[MITgcm-devel] another bug in growth.F ?
Baylor Fox-Kemper
baylor at MIT.EDU
Mon Dec 4 09:22:04 EST 2006
Hi Martin,
Love to see the .glob.nc files!
-Baylor
On Dec 4, 2006, at 4:53 AM, Martin Losch wrote:
> More on seaice/thsice.
>
> I have put a few results of my 2deg experiment (to 80N), forced
> with CORE (modified NCAR/NCEP reanalysis) climatology:
>
> http://mitgcm.org/~mlosch/run40
> http://mitgcm.org/~mlosch/run41
> http://mitgcm.org/~mlosch/run42
> http://mitgcm.org/~mlosch/run43
> http://mitgcm.org/~mlosch/run44
> http://mitgcm.org/~mlosch/run45
> http://mitgcm.org/~mlosch/run46
>
> runs 40,41,42,45 are with seaice and growth-thermodynamics, runs
> 43,44,46 with seaice+thsice. All netcdf files are 10day averages in
> the 101st year of integration, except for run43, which crashes at
> some time in the 6th decade, so that the netcdf files contains the
> 51st year. I use asynchronous timestepping
> (deltaTtracer=12h,deltaTmom=20min) for all runs. there are also
> figures with appropriate files name (run40.png, etc) showing
> effective snow and ice thickness and ice concentration in march and
> august for the antarctic ocean. Details:
> run40, not advection of snow, flooding (also included grid.*
> files). Here you see the strange snow patterns, where snow is as
> high as 160m (not included in colorscale), and depresses the sea
> surface by as much as 160m*0.33.
> run41, advection of snow (scheme 2 for all variables): advection
> distributes the snow and thing look more physical
> run42, advection of snow (scheme 2 for all variables),
> flooding=true: a lot less snow but much more ice, too much if you
> ask me.
> run45, advection of snow and flooding, but advection scheme 1 for
> all variables: the different advection schemes makes the solution
> smoother, but not better, as expected.
> run43, with thsice as is in the repository (crashed during the 6th
> decade, don't know why), this version of the code should probable
> vanish pretty soon? tiny concentrations/thicknesses at the ice margins
> run44, with thsice and JMC's "new version" in seaice_advdiff.F: too
> be compared with run45. thsice leads to even more ice than the
> simpler thermodynamics of run45. Thickness is way too high (compare
> with www.seaice.de), and in summer the Eastern Weddell Sea should
> be almost ice free (only some ice along the Peninsula).
> run46, like run44, but flooding turn off (commented out in
> thsice_calc_thickn.F): the flooding algorithm has less of an impact
> on the solution than for growth.
>
> For a comparision with observations of concentrations see
> www.seaice.de, eg. March15, 2006 (from AMSR-E):
> http://iup.physik.uni-bremen.de:8084/amsredata/asi_daygrid_swath/
> l1a/s6250/2006/mar/asi-s6250-20060314-v5_nic.png
> Aug15,2006
> http://iup.physik.uni-bremen.de:8084/amsredata/asi_daygrid_swath/
> l1a/s6250/2006/aug/asi-s6250-20060815-v5_nic.png
>
> same dates in 1999 from SSMI
> http://iup.physik.uni-bremen.de:8084/archive/south/1999/19990315.png
> http://iup.physik.uni-bremen.de:8084/archive/south/1999/19990815.png
>
> So, as far as I can see, the model produces first order
> distriubtions in all cases with too much extend in summer, too much
> ice in general and too much snow. Not too bad, but how much of this
> do we expect. I'll go and consult with my trusty ice specialists.
> But maybe someone on this list can comment too (Jinlun?)
>
> Martin
>
> On 30 Nov 2006, at 17:37, Martin Losch wrote:
>
>> Hi Dimitris and others,
>>
>> I have no 100year of running my 2deg configuration with isotropic
>> grid in the southern hemisphere for 41 different parameter
>> combinations/code versions. Here is my superficial summary:
>> 1. The crucial fix for the sea ice distribution (AREA+HEFF) is the
>> evap*(1-area) fix. I think we can agree on that
>> 2. If snow is not advected or turned into ice by submersion
>> (flooding algorithm), it accumulates at rates of more than 1m/y
>> consistent with the surface forcing (precipitation) provided by
>> the CORE climatology. This happens only in areas with perennial
>> ice cover and only in the southern hemisphere (my domain stops at
>> 80N). The pattern of snow accumulation is a little strange, which
>> is the straw that I cling to in thinking that there is still a bug
>> in the handling of snow in growth (see attached figure for a
>> typical pattern, run40).
>> 3. If I use flooding but no advection of snow, the snow look OK,
>> but there is far too much ice (thickness), especially in summer
>> (area), run38 in a previous figure.
>> 4. If I use advection of snow but no flooding, the snow is
>> distributed and can melt (I guess), run41 in attached figure.
>> There is still a litte too much snow after 100 year (3.6m in a few
>> areas west of the Antarctic peninsula, but I could live with
>> that). Be aware that the advection I use is the 2nd order
>> (default) advection, and I am afraid, that the advection of snow
>> is not properly done in this case, but that should be a minor
>> issue. Ice looks reasonable in this case maybe a little thin in a
>> few areas in summer, but appears to be problem of the 0-layer
>> thermodynamics, I guess.
>> 5. What will happen with flooding and advection of snow I don't
>> know yet (not part of my 41 different combinations), but tomorrow
>> (will this be run42?).
>>
>> So my preliminary conclusions are:
>> 1. The snow is still not handled properly in growth/seaice_advdiff
>> 2. with advection of snow the problems are smallest (may be even
>> smaller with additional flooding)
>>
>> Martin
>>
>> <snow4041.png>
>>
>> On 30 Nov 2006, at 16:49, Dimitris Menemenlis wrote:
>>
>>> Jinlun, the beer/crap comment was in jest. Everyone who has used
>>> pkg/seaice appreciates your effort in making this package
>>> available to MITgcm and also your subsequent help with bug fixes
>>> and with other modifications.
>>>
>>> Martin, I also find that
>>>
>>>> cdm IF(FICE(I,J,bi,bj).GT.ZERO) THEN
>>>> IF(atemp(i,j,bi,bj).LE.273.15 _d 0 ) THEN
>>>
>>> has very little impact on growth.F both for the forward solution
>>> as well as for the high forward sensitivity of the model that you
>>> and Patrick reported. What does remove the high forward
>>> sensitivity is commenting out the snow-melt addition.
>>>
>>>> C Now melt snow if there is residual heat left in surface
>>>> level C Note that units of YNEG and SEAICE_SALT
>>>> are m of ice cdm IF(RESID_HEAT
>>>> (I,J,bi,bj).GT.ZERO.AND. cdm
>>>> & HSNOW(I,J,bi,bj).GT.ZERO)
>>>> THEN cdm GHEFF(I,J)=MIN
>>>> (HSNOW(I,J,bi,bj)/SDF/ICE_DENS, cdm
>>>> & RESID_HEAT
>>>> (I,J,bi,bj))
>>>> cdm YNEG(I,J,bi,bj)=YNEG(I,J,bi,bj)+GHEFF
>>>> (I,J) cdm HSNOW(I,J,bi,bj)=HSNOW
>>>> (I,J,bi,bj)-GHEFF(I,J)*SDF*ICE_DENS cdm
>>>> SEAICE_SALT(I,J,bi,bj)=SEAICE_SALT(I,J,bi,bj)-GHEFF
>>>> (I,J) cdm ENDIF
>>>
>>> So back to where we were before latest exchange.
>>>
>>> Dimitris
>>>
>>> --
>>> Dimitris Menemenlis <menemenlis at jpl.nasa.gov>
>>> Jet Propulsion Lab, California Institute of Technology
>>> MS 300-323, 4800 Oak Grove Dr, Pasadena CA 91109-8099
>>> tel: 818-354-1656; fax: 818-393-6720
>>> _______________________________________________
>>> MITgcm-devel mailing list
>>> MITgcm-devel at mitgcm.org
>>> http://mitgcm.org/mailman/listinfo/mitgcm-devel
>>
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