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NCSS return confusing for lat/lon data #1048
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This issue is related to #450 and #337: NCSS NetCDF output files only include selected data variables and the variables that comprise their coordinate systems. NCSS is not smart enough to examine attributes to find other variables that should be included. Auxiliary coordinate variables (i.e. variables listed in the |
While I don't doubt the sentiment of your statement, the fact that this problem doesn't occur with e.g. Lambert Conformal output from HRRR on TDS would seems to indicate that the problem is specific to lat/lon coordinate systems, and not a more general NCSS issue. |
Hmm, you're right. First, in addition to the variables I mentioned above, NCSS also includes the coordinate transform variables. However, when a Does anyone know why this decision was made? Perhaps John forgot that there are some cases where including a |
I'm guessing that's right. CF doesn't require it, but it also doesn't mind if you do include it. My preference is to include it always, because it simplifies my code (though I'll probably have to deal with lat/lon data without it from other source); if we leave it out, then we just need to make sure that it doesn't list a |
No idea why According to CF:
I'd say we should always include it for maximum clarity. |
For a straightforward request for data from models on lat/lon grids (say: http:https://thredds.ucar.edu/thredds/ncss/grib/NCEP/GFS/Global_0p5deg/GFS_Global_0p5deg_20180302_0000.grib2?var=Temperature_isobaric&disableLLSubset=on&disableProjSubset=on&horizStride=1&time_start=2018-03-02T00%3A00%3A00Z&time_end=2018-03-18T00%3A00%3A00Z&timeStride=1&vertCoord=&accept=netcdf4), the return doesn't seem to be CF-compliant:
Specifically, the
grid_mapping
attribute references aLatLon_Projection
variable, which is not included in the file. While it's not necessary, it would probably be good to include this as alatitude_longitude
projection so that the assumed radius of the earth can be included.I have this this on 0.5 GFS and WW3 output. A netCDF file generated a year ago (for the 0.25 GFS) doesn't seem to have this problem--but only because there isn't a
grid_mapping
attribute. I'm not sure that's actually better.The text was updated successfully, but these errors were encountered: