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attribute "coordinates" lost

Added by Jay Su over 6 years ago

I am using CDO to subset IMERG data:

cdo -s -L -f nc4 -sellonlatbox,10.0,20.0,10.0,20.0 -selname,precipitationCal 3B-DAY-E.MS.MRG.3IMERG.20170501-S000000-E235959.V04.nc4 tmp.nc4

The attribute "coordinates" is removed for all variables. May I ask why and how I can fix it?

Thanks,


Replies (5)

RE: attribute "coordinates" lost - Added by Karin Meier-Fleischer over 6 years ago

Hi Jay,

I don't have IMERG data, so is it possible to upload the data?

-Karin

RE: attribute "coordinates" lost - Added by Karin Meier-Fleischer over 6 years ago

I think the problem is that the coordinates attribute is of type NC_STRING and not NC_CHAR which violates the CF convention.

But you can add the coordinates using the setattributes operator:

  cdo -setattribute,precipitationCal@coordinates="lat lon" tmp.nc4 tmp_with_coordinates.nc4

-Karin

RE: attribute "coordinates" lost - Added by Jay Su over 6 years ago

Thank you Karin,

So we are expecting coordinates to be NC_CHAR, right? I could not find it in the CF convention v1.7 though ...

By cdo -setattribute,precipitationCal@coordinates="lat lon", is it now NC_CHAR, not NC_STRING?

Is it possible we can bypass the checking in CDO? It will be tedious if I have to manually set back for all the variables.

RE: attribute "coordinates" lost - Added by Ralf Mueller over 6 years ago

hi Jay!

your upload has a regular lonlat grid - the coordinates attribute is not needed for this type of grid. Thats why CDO ignores it and doesn't keep it.

if a data variable used the lon,lat as horizontal dimensions and there are data variables with the same name, the CF-convention is fulfilled - no extra attribute needed.

hth
ralf

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