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Re: non-orthogonal grid

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  • Subject: Re: non-orthogonal grid
  • Date: Mon, 15 Nov 2004 13:17:33 -0700
>To: address@hidden
>From: "Mario Germano" <address@hidden>
>Subject: Re: 20041111: non-orthogonal grid
>Organization:
>Keywords: 200411110425.iAB4P0i8028102

Mario,

> Thanks for your answer Russ,
> 
> I've tried to define dimensions like you have suggested (see you previous
> email).
> However, I'm not sure of how to introduce data. I've written the following
> in the "data" part of the cdl file:
> 
>   m=1,2,3,4,5,...,100;
>   n=1,2,3,4,5,...,75;
>   lon=m × n matrix of real values;
>   lat= m × n matrix of real values;
>   wind_speed = m × n matrix of real values;
>   temperature = m × n matrix of real values;
> 
> 
> After having transformed the cdl file into a cdf file (via ncgen), ferret
> gives me the following error message when trying to list the wind_speed or
> the temperature variable:
> **ERROR: dimensions improperly specified: 9999999 words were requested.
>  *** NOTE: Check for unspecified limits on an ABSTRACT axis
>  *** NOTE: Use the SHOW GRID command to see the axes
> 
> Can you tell me why ?

This may be a Ferret question rather than a netCDF question, in which
case it would be better to direct it to the developers/maintainers of
Ferret:

  http://ferret.pmel.noaa.gov/Ferret/ferret_support.html

I suspect the answer is that Ferret requires data that adheres to the
COARDS standard conventions:

  http://www.ferret.noaa.gov/noaa_coop/coop_cdf_profile.html

which do not permit multidimensional coordinate variables such as
lat(m,n) and lon(m,n) as you have defined them.  There may be some
other way of representing such data that Ferret understands, but for
that it would be best to consult the Ferret developers or maintainers
or the Ferret email list.  There was a brief description of this on
the ferret email list a few years ago:

  http://ferret.pmel.noaa.gov/Ferret/Mail_Archives/fu_98/msg00246.html
  http://ferret.pmel.noaa.gov/Ferret/Mail_Archives/fu_98/msg00247.html

that doesn't provide a way to do what you want except to interpolate
onto a regular lat/lon grid, which is probably unsatisfactory ...

--Russ