Open cwardgar opened 7 years ago
That's a good question. My guess is the ensemble work in netCDF-Java was based on some CF related conversations that never made it into the standard.
The _CoordinateAxisType=Ensemble
is netCDF-Java specific (the _Coordinate Attribute Convention). Outside of that, I'm not sure there is an official convention that handles ensemble data at this point.
Hmm, I didn't realize it wasn't part of any standard. In that case, maybe this issue should be to better document Unidata's treatment of the axis.
There is an "standard_name" on CF to represent ensembles coordinate: standard_name='realization'
http://cfconventions.org/Data/cf-standard-names/44/build/cf-standard-name-table.html#realization
TDS5 it's supporting it but TDS4.X was using 'ensemble'
This was mentioned on the netcdf-java mail list http://www.unidata.ucar.edu/mailing_lists/archives/netcdf-java/2016/msg00146.html
This is the conclusion:
The netcdf-java 4.6.X recognizes the standard_name='ensemble' for Ensembles Axis Type. https://github.com/Unidata/thredds/blob/master/cdm/src/main/java/ucar/nc2/dataset/conv/CF1Convention.java#L157-L160 but 'ensemble' is not a recognized CF standard_name. It should be 'realization' as you have put into the ensemble_member
The netcdf-java 5.0.0, adds 'realization' as possible standard_name value for Ensembles Axis Type https://github.com/Unidata/thredds/blob/5.0.0/cdm/src/main/java/ucar/nc2/dataset/conv/CF1Convention.java#L162-L165
From HMD-769692.
In order for a variable to be identified as an Ensemble
CoordinateAxis
in a gridded dataset:_CoordinateAxisType=Ensemble
attribute ORstandard_name=ensemble
attribute AND the dataset must have aConventions=CF-1.X
global attribute.I think we can do better than that. In particular, why are we detecting Ensemble axes ONLY for the CF conventions?