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- CF standard: add a dummy variable crs and add all grid mapping related meta-data as attributes.
- The ADAGUC WMS/WCS software requires some additional attributes that contain the same information as the CF grid_mapping attributes: proj4_params and epsg_code. In the Dutch National Model and Data Centre NMDC.eu ADAGUC is used as a central component, so for NMDC these additional attributes are highly recommended.
Code Block netcdf test_map { variables: double var(n); var:proj4_params = "+proj=longlat +ellps=WGS84 +datum=WGS84 +no_defs" ; var:EPSG_code = "EPSG:4326"; }
- Proposal for multiple coordinate systems: https://cf-pcmdi.llnl.gov/trac/wiki/MultipleProjections
- proposed extension: add a WKT (well-known text) string of all grid mapping related meta-data (the WKT quite laborious for parsing though). Note that the plethora of brackets and slashes can ruin opendap access to a netCDF file, see the following slash*.nc examples.
- proposed extension: make sure that the dummy variable crs it an integer and that its value is the EPSG code of the coordinate system, e.g:
- 28992 for Dutch Rijksdriehoek (projection_x_coordinate,projection_y_coordinate)
- 4326 for WGS84 global ellipsoid (latitude, longitude)
- 32631 for WGS 84 / UTM zone 31N (projection_x_coordinate,projection_y_coordinate)
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