[MITgcm-devel] another bug in growth.F ?
Martin Losch
Martin.Losch at awi.de
Mon Dec 4 11:55:48 EST 2006
Hi Baylor,
I am not familiar enough with rdmnc to know what's going on in there.
I agree that changing global attributes is a bad choice, however if
rdmnc relies on it ... Maybe we can hack it by saying: if only 1
file, or a files that end on glob.nc, then overide? But that's a
dirty hack that is likely to break at the first instance, something
is changed ... I have no good solution.
Martin
On 4 Dec 2006, at 17:49, Baylor Fox-Kemper wrote:
> Hi Martin,
> That is curious, since I don't seem to be able to get 330x200
> from a sensible combination of snx/sny and the resolutions. I
> don't want to change the attributes in the glob.nc files, since
> they give the 'historical' values that were used in the data file.
> Maybe we just need to add an override function in readmnc to make
> it ignore the attributes snx and sny and just use 1 for both?
> Tell me what you think.
> -Baylor
>
> On Dec 4, 2006, at 11:13 AM, Martin Losch wrote:
>
>> 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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