Mary Jo,
It's a problem that doesn't currently have an official solution. The
geospatial_lat/lon_resolution are from the ESIP Attribute Convention for
Dataset Discovery (ACDD) <
http://wiki.esipfed.org/index.php/ACDD>, but
they haven't thought through to a generalization yet. You could make
your own attributes geospatial_resolution or geospatial_x_resolution and
geospatial_y_resolution, or you could think of longitude as being ~x and
latitude as ~y and use the existing attributes. You can also query the
ESIP people and request that they add a new set of attributes that would
handle this. I think the CF community likely considers this to be more
of an ACDD issue.
Grace and peace,
Jim
On 8/16/16 12:33 PM, Mary Jo Brodzik wrote:
>
> I am producing a gridded data set using CF-1.6 conventions. In a
> given file, the data are projected onto one of three possible
> projections: Northern or Southern Lambert Azimuthal Equal Area (LAEA),
> or Cylindrical Equal-Area (CEA). With each data variable in the file,
> I do include the grid_mapping attribute and I am populating my
> grid_mapping variable with the required projection information as
> listed here:
>
> http://cfconventions.org/cf-conventions/v1.6.0/cf-conventions.html
>
> Also in a given file, the spatial resolution will be one of 25, 12.5,
> 6.25 or 3.125 km, and although this is obvious from the x and y
> dimension variable values, I am looking for a place to include the
> spatial resolution for a human who is reading the metadata.
>
> I assume an attribute in the grid_mapping variable would be the place
> for this. At first I thought it was one of the "scale_factor*"
> attributes, e.g. "scale_factor_at_projection_origin", but for CEA,
> this would be a misnomer, since the value is the scale at true
> latitude, not the projection origin at all. Also, the convention says
> to include "either standard_parallel or
> scale_factor_at_projection_origin", so now I'm beginning to think
> these "scale_factor_*" attributes are not the correct place at all for
> this information.
>
> I see in the NCEI template file for gridded data
>
> https://www.nodc.noaa.gov/data/formats/netcdf/v2.0/grid.cdl
>
> that they recommend global attributes like "geospatial_lat_resolution"
> and "geospatial_lon_resolution", with a string value of "0.1 degree"
> or "100 meters" which is almost what I am looking for, but of course
> since I have projected data it would not be "lat" or "lon".
>
> Can anyone recommend a best practice for my projected data case that I
> can follow?
>
> Thank you,
> Mary Jo Brodzik
>
> ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> Mary Jo Brodzik, Senior Associate Scientist, 303-492-8263
> NSIDC/CIRES, Univ. of Colo. at Boulder, 449 UCB, Boulder, CO 80309-0449
> ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> _______________________________________________
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> CF-metadata at cgd.ucar.edu
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Received on Tue Aug 16 2016 - 10:43:57 BST
