[netcdf-java] netcdf-java selects wrong grid_mapping if several grid_mapping_name variables are present

• To: netcdf-java@xxxxxxxxxxxxxxxx
• Subject: [netcdf-java] netcdf-java selects wrong grid_mapping if several grid_mapping_name variables are present
• From: Heiko Klein <Heiko.Klein@xxxxxx>
• Date: Fri, 30 Apr 2010 16:24:56 +0200

Hi,

netcdf-java seems to ignore the grid_mapping attribute if several
grid_mapping_name variables are present:

I'm currently reprojecting some data from

        int projection_1 ;
                projection_1:grid_mapping_name = "polar_stereographic" ;
                ...

to

        int projection_stere ;
                projection_stere:grid_mapping_name = "polar_stereographic" ;
                ...

The reprojected altitude has now the attributes:
        short altitude(time, y, x) ;
                altitude:standard_name = "altitude" ;
                altitude:units = "m" ;
                altitude:coordinates = "lon lat" ;
                altitude:grid_mapping = "projection_stere" ;


For reference, I still keep the original 'projection_1' variable in the
file. But whenever I try to view the altitude (idv (webstart),
netcdf-toolsUI (4.1)), the data is distorted because netcdf-java assumes
'projection_1' to be the correct projection for 'altitude'.

I can solve the problem by completely deleting the projection_1
variable, but since I use the 'altude:grid_mapping =
"projection_stere"', this shouldn't be neccessary.


An example-file with altitude around Greenland is attached.

Best regards,

Heiko

Attachment: out.nc
Description: Cdf file

• Follow-Ups:
  • Re: [netcdf-java] netcdf-java selects wrong grid_mapping if several grid_mapping_name variables are present
    • From: John Caron