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Re: 20030714: IDV and CF files with sigma or ocean-s vertical coordinates (cont.)

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  • Subject: Re: 20030714: IDV and CF files with sigma or ocean-s vertical coordinates (cont.)
  • Date: Mon, 14 Jul 2003 17:20:25 -0600
Rich,

John Caron is about to leave on vacation so I will send what he was
going to point out.

The files you sent me omit an attribute needed for two-dimensional
latitude, longitude coordinate variables. In the CF Metadata Conventions
document,
http://www.cgd.ucar.edu/cms/eaton/cf-metadata/CF-current.html#grid_ex2,
an example is shown with the two-dimensional coordinates "lat" and
"lon." Note the attribute for parameter T, 'T:coordinates = "lon lat"
;'.  In your file you need 
h:coordinates = "latitude, longitude"; 
for any parameter h. Without the "coordinates" attribute the file is not
CF compliant and a netCDF file reader does not find the coordinate
system.  The CF checker must miss checking for this attribute. 

The IDV cannot yet display 3D data with ocean s coordinate, but it
should be able to display your 2D file with the coordinates attribute
added.

John has completed his part of the work on the s and hybrid sigmas
coordinates, finding the z coordinate height values from s or hybrid
sigma values in the netCDf file, and now I will be working on using them
in the IDV data model. Since each z value depends on lat, lon, and time
this is not a simple addition and I cannot say when it will be done. At
the earliest this will be in the next IDV release. No release date has
been set. (We have had 5 releases so far this year.)

Stu

> 
> Thanks for confirming that IDV cannot currently read
> 2D lat/lon.  I wasn't sure whether it was my problem or
> not.
> 
> But thanks even more for confirming that you are working
> on including the capability!
> 
> -Rich

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