[CF-metadata] (no subject)

[mcginnis at ucar.edu]

Hi all,

I'm wondering how to properly apply the 'axis' attribute to coordinate 
variables in a curvilinear/two-dimensional coordinate system.

I have data in a Lambert conformal projection, so I have coordinate 
variables in x & y, and auxiliary coordinate variables in lat & lon.  
Like this:


dimensions:
         yc = 135 ;
         xc = 160 ;
         time = UNLIMITED ; // (5848 currently)
variables:
         double yc(yc) ;
                 yc:long_name = "y-coordinate of Cartesian system" ;
                 yc:units = "km" ;
         double xc(xc) ;
                 xc:long_name = "x-coordinate Cartesian system" ;
                 xc:units = "km" ;
         double lon(yc, xc) ;
                 lon:long_name = "longitude" ;
                 lon:units = "degrees_east" ;
         double lat(yc, xc) ;
                 lat:long_name = "latitude" ;
                 lat:units = "degrees_north" ;
         double time(time) ;
                 time:long_name = "time" ;
                 time:axis = "T" ;
                 time:units = "days since 1979-01-01 00:00:0.0" ;
         float temp(time, yc, xc) ;
                 temp:units = "K" ;
                 temp:long_name = "Surface Temperature";
                 temp:coordinates = "lon lat" ;


My question is, which variables is it appropriate to define an 'axis' 
attribute with the value "X" for: xc, lon, both, or neither?

Thanks,

Seth


----
Seth McGinnis
Associate Scientist
ISSE/NCAR

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