[ncl-talk] Polar stereographic plots of tripole grids

Thu Sep 19 09:45:02 MDT 2019

Hi Abby,

This is always the challenge with tripole grids. Here is an example from a
CICE run on the MOM6 tripole grid:

http://webext.cgd.ucar.edu/MOM/bmom.e20.BMOM.f09_t061.long_run_mct.001/ice/bmom.e20.BMOM.f09_t061.long_run_mct.001-obs/yrs1-100/contour/con_ann_hi_cice.png

I always add 'res at gsnAddCycle = True' to all of my plots, but this doesn't
quite cover the tripole zipper. The only way to do it is add an extra row
at the northern edge of the domain.

Dave

On Thu, Sep 19, 2019 at 9:39 AM Abigail Smith via ncl-talk <
ncl-talk at ucar.edu> wrote:

> Hi Dennis,
>
> Thanks for your quick response! And thank you for clarifying about the
> coordinate variables.
>
> However, in the plot you attached there are large gaps in the Arctic
> Ocean. I realize that this is due to the shape of the grid, but using
> lat2d/lon2d seems to do a slightly better job of mapping data onto those
> areas, except for the gap passing through 90 degrees N (as seen in the
> original pdf that I attached). Do you know if there's a way to maximize the
> area that the data maps to, such that there are no gaps?
>
> Best,
> Abigail
>
> On Wed, Sep 18, 2019 at 9:30 PM Dennis Shea <shea at ucar.edu> wrote:
>
>> float siconc(time, lat, lon)
>> where lat(lat) and lon(lon) are coordinate variables.
>> There is no need to use @lat2d, @lon2d
>>
>> The original file was renamed when I downloaded:
>>
>> test.siconc_SIday_BCC-CSM2-MR.nc
>> <http://secure-web.cisco.com/1ul9UbLFj_X6lncl6JMMTi4Z0LU5goBypbouOMvqKAEissidSQKpjXLz-EwLcj3xMGAUbf7OK-l3t-klD4b2rnt1dNK-_zHMNcI5EbARZMGyYkxMwO9cwRwRB8YYP9NYvGkoyrRXsjo8gAXyO31V5cZp17lv3lLMtlrokhjzZPlWGN8md9hSOw3Wf7trO8o3kwOVEPJuXW77J3JsJ9-QSbco3QxsMKoZbg1n5Bwqwg7EaKVxpbsHjumHA-DgtzW_Wy3-64mGcPvfIvQekJLi7TxRVLrNpm9SBFYJU77LIZ2PX_OSg-WiXuXR-PJgw4TH7L6AtBQqC9tpytJAzU11iwKARvBOeR-z_qZKlrUJZ9Dn3-sVi3cAQrJksvjuzR_8b1RqgPEZnA2aC6AbdMqwkWaPNx97aX3ae0ajtBHKPphzDfS_qg9oQ0TK62DC864Xg/http%3A%2F%2Ftest.siconc_SIday_BCC-CSM2-MR.nc>
>> <==  siconc_SIday_BCC-CSM2-MR_historical_r1i1p1f1_gn_19000101-19091231.nc
>> ===
>> Variable: sic
>> Type: float
>> Total Size: 121939200 bytes
>>             30484800 values
>> Number of Dimensions: 3
>> Dimensions and sizes: *[time | 365] x [lat | 232] x [lon | 360]*
>> Coordinates:
>>             time: [ 0.5..364.5]
>>
>> *           lat: [-81.5..89.5]   <== coordinate variable            lon:
>> [ 0.5..359.5]  <== coordinate variable*
>> Number Of Attributes: 11
>>   standard_name : sea_ice_area_fraction
>>   long_name : Sea Ice Area Fraction (Ocean Grid)
>>   comment : Area fraction of grid cell covered by sea ice
>>   *units : %*
>>   original_name : CN
>>   cell_methods : area: mean where sea time: mean
>>   cell_measures : area: areacello
>>   history : 2018-11-27T09:03:20Z altered by CMOR: Treated scalar
>> dimension: 'type'.
>>   coordinates : type latitude longitude
>>   missing_value : 1e+20
>>   _FillValue : 1e+20
>>
>>
>> See attached:
>>
>> *%> ncl* siconc.ncl
>>
>>
>> On Wed, Sep 18, 2019 at 2:00 PM Abigail Smith via ncl-talk <
>> ncl-talk at ucar.edu> wrote:
>>
>>> Hi NCL-talk,
>>>
>>> I'm attempting to create polar stereographic contour plots of Arctic sea
>>> ice from various CMIP models on their native grids. Some of the grids are
>>> tripole, so I end up having the same gap as seen in ice_4.ncl at
>>> https://www.ncl.ucar.edu/Applications/orca.shtml. I want to remove the
>>> gap, but the solution in ice_4.ncl uses U-fold grid coordinates, which
>>> aren't provided for many CMIP models.
>>>
>>> I've attached an example script and the plot it produces. The data are
>>> available for download here:
>>>
>>> https://handle-esgf.dkrz.de/lp/21.14100/c55636b2-3c1a-4735-8243-4e62310acbc3
>>> <https://secure-web.cisco.com/1yJctVysxmtw-Ey_-bTATuatmIfgwB_PPX3DpPQbX966Md4RBVe5Og6JJoKylyKORLv3UywkR6yJay4Uu1hsNPoRfDs4ye7bjONPTKDvuhHiNPaKg2HL1Mn5YV8QjpmQWiHKNT7ZzX5dzGQELsJHuupS6TipNVI7-Y6ksQfzlBw_swbE6N4nu15LKyLloKESepVNAuyYsw24x5__PuDAegxI3aPUT74MGoPraBGT9MMXwUM8YXV9r7aW_0dIkNM8QM_Kt4wSA_9aomjcdRY4ts4W2cWopqO0dnC5Lnn0dQ3iv2i_I2g08x75rzcTf6E8XmuvOXcSJADU-J92vZMxS9Ap1ZNCFu6AxmBRAsJ5aeJclzvolz_yVnsgvGmzL1Sr1cOoQMWAJMF9PWnUYdsO4znxrVkFD-KEOjyh9V70jiw-FI4zRdIOS46KR6xmWtaz1igTiJYFnWkiBOGqPUsUhRw/https%3A%2F%2Fhandle-esgf.dkrz.de%2Flp%2F21.14100%2Fc55636b2-3c1a-4735-8243-4e62310acbc3>
>>> I'm running ncl version 6.3.0 and not getting any error messages.
>>>
>>> Thanks in advance for considering this issue!
>>>
>>> Best,
>>> Abigail Smith
>>> University of Colorado Boulder
>>> _______________________________________________
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>>
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-- 

David A Bailey
 email: dbailey_at_ucar.edu
National Center for Atmospheric Research   phone: 303-497-1737
PO Box 3000
fax  : 303-497-1700
Boulder, CO 80307-3000
                   http://www.cgd.ucar.edu/staff/dbailey
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