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  • Subject:
  • Date: Thu, 11 Nov 2004 14:42:37 -0700
>To: address@hidden
>From: "Mario Germano" <address@hidden>
>Subject: Re: 20041111: non-orthogonal grid
>Organization: 
>Keywords: 200411110425.iAB4P0i8028102

Hi Mario,

> I am experiencing difficulties in inserting grid points in a cdf file (using
> FORTRAN) because these points have all different lon-lat coordinates: they
> are not uniformly distributed on an orthogonal grid, but rather on a rotated
> grid.
> 
> Ideally I'd like to be able to insert points one by one using a syntax like:
>    insert_point(lon,lat,wind_speed, temperature,.)
> I ignore if such a thing is possible.

I think you need to define two extra variables to hold the latitudes
and longitudes for points on the grid:

 dimensions:
   m = 100;  // for example
   n = 75;   // for example
 variables:
   double lat(m,n); // latitude of the (m,n) grid point
   double lon(m,n); // longitude of the (m,n) grid point
   float wind_speed(m,n);
   float temperature(m,n);
    ...

Conventions for storing such grids in netCDF files are discussed in
the "CF conventions", section 5.2:

  http://www.cgd.ucar.edu/cms/eaton/cf-metadata/CF-1.0.html
  http://www.cgd.ucar.edu/cms/eaton/cf-metadata/CF-1.0.html#grid_ex2

--Russ
_____________________________________________________________________

Russ Rew                                         UCAR Unidata Program
address@hidden          http://www.unidata.ucar.edu/staff/russ