[ncl-talk] Polar stereographic plots of tripole grids

[Abigail Smith]

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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