[netcdf-java] Geostationary CF grid_mapping problem: "HTTP Status 500 - Internal Server Error" [SEC=UNCLASSIFIED]

• To: "netcdf-java@xxxxxxxxxxxxxxxx" <netcdf-java@xxxxxxxxxxxxxxxx>
• Subject: [netcdf-java] Geostationary CF grid_mapping problem: "HTTP Status 500 - Internal Server Error" [SEC=UNCLASSIFIED]
• From: Leon Majewski <Leon.Majewski@xxxxxxxxxx>
• Date: Wed, 13 May 2015 07:52:28 +1000

Hi,
I've been using the vertical_perspective CF1.6 grid_mapping to display 
geostationary satellite data. The limitation of the implementation within 
netcdf-java is the handling of the earth_radius (only one term instead of 
semi_minor_axis and semi_major_axis), which results in coastline mis-match in 
opendap-thredds generated WMS and netcdf subset service output.

It's been suggested that I use the CF1.7 grid_mapping geostationary, as this 
handles the semi_major and semi_minor_axis parameters correctly. To do so 
should simply be a matter of replacing 'vertical_perspective' with 
'geostationary' and ensuring the semi_major and semi_minor_axis parameters are 
specified. However, I can't get opendap-thredds [Version 4.5.5 - 20150306.1537] 
to identify the grid_mapping=geostationary. I get "HTTP Status 500 - Internal 
Server Error" when I try to access the WMS. Selected CDL for my example is 
below.

Has anyone else seen this behaviour? 
Thanks,
Leon

        float channel_0013_brightness_temperature(time, y, x) ;
                channel_0013_brightness_temperature:grid_mapping = 
"geostationary" ;

        float geostationary ;
                geostationary:latitude_of_projection_origin = 0. ;
                geostationary:longitude_of_projection_origin = 140.7 ;
                geostationary:grid_mapping_name = "geostationary" ;
                geostationary:perspective_point_height = 35785863 ;
                geostationary:semi_major_axis = 6378137. ;
                geostationary:semi_minor_axis = 6356752.3 ;
                geostationary:proj4_string = "+proj=geos +lon_0=140.7 
+h=35785863 +a=6378137.0 +b=6356752.3" ;

// global attributes:
                :Conventions = "CF-1.7" ;
                :standard_name_vocabulary = "CF-1.7" ;