[CF-metadata] Using "axis" with curvilinear coordinates

From: mcginnis at ucar.edu <mcginnis>
Date: Thu, 5 Jul 2007 18:47:36 -0600

[Reposting with a subject -- sorry for the duplication]

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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Received on Thu Jul 05 2007 - 18:47:36 BST