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

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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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