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20050720: CF1.0 compliant .nc file problems

Date: Wed, 20 Jul 2005 12:58:11 -0700
From: Stuart Maclean <address@hidden>
To: address@hidden
Subject: CF1.0 compliant .nc file problems

Hi Stuart-

Your message to idvusers bounced because the attachment was too big.
We limit the size of attachments.

> I am trying to get IDV to read and display output of an mm5 model.  I am
>   looking at the CF1.0 convention as the target output format for my mm5
> to .nc converter tool.  The map projection is lambert conformal.
> 
> The resultant .nc file will load and display but the units seem way off.
>   Moving the mouse around the main display shows loony lat/lon values
> e.g. lat = -136.  Contours for data values such as surface temp are
> rendered in such a way that the contouring is right, it's just somehow
> the lat/lon bounds are much bigger than the world under the default map
> projection id IDV.
> 
> I found an example CF-1.0 file, from the RUC model
> (http://my.unidata.ucar.edu/content/software/netcdf/examples/RUC.nc),
> which displays perfectly in IDV.  Using ncdump as a comparator, I am
> trying to get my .nc file to follow the RUC format.  I have added many
> attributes from the RUC file which don't appear in the CF conventions
> doc which i thought IDV may be requiring (e.g. projectionCoordSys), but
> to no avail...
> 
> I notice that the RUC file has both the lists of x and y values in
> meters AND the full lists of lat and lon points?  Is this required for
> IDV?  Are the lat/lon pairs not derivable from the x,y lists, given the
> map projection parameters included.
> 
> I've attached the .cdl file for my data in the hope that someone can
> enlighten me ;)

This is a bug in the 1.2b2 release, but you file seems to work fine
in the 1.2RC1 and the (soon to be released) 1.2 versions.  You can
access the 1.2RC1 version from:

http://my.unidata.ucar.edu/content/software/idv/release/idv_1.2rc1/index.html

Thanks for providing the file to test with.

Don Murray
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