[MITgcm-devel] another bug in growth.F ?
Martin Losch
Martin.Losch at awi.de
Mon Dec 4 11:13:46 EST 2006
Hi Baylor,
there is a small bug still: when I try to read the glob.nc files with
rdmnc, the dimension of the fields are wrong, e.g., if you try to
read one of the files that I described in my previous email, the
dimension of the fields should be 180x120, but they are in fact
330x200, which I do not quite understand, it must have to do the sNx/
sNy in the global attributes or something else that rdmnc uses to
assemble files and now misinterprets within the glob.nc files.
M.
On 4 Dec 2006, at 15:22, Baylor Fox-Kemper wrote:
> 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
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