[IDV #DMJ-221042]: IDV - No content found in netCDF file

Hi Mark-

> Institution: NGDC/NOAA
> Package Version: 2.0
> Operating System: os.name:Windows XP; os.arch:x86; os.version:5.1;
> Hardware Information: java.vendor:Sun Microsystems Inc.; 
> java.version:1.5.0_07; java.home:C:\\Program Files\\Java\\jre1.5.0_07; 
> j3d.version:1.3.2 fcs (build12); j3d.vendor:Sun Microsystems, Inc.; 
> j3d.renderer:OpenGL;
> Inquiry: Hello -- when I open the attached netCDF file in IDV the Field 
> Selector shows nothing --
> no variables, grids, or anything at all. Can you tell me what I need to do to 
> make this netCDF
> file readable by IDV?

There are a couple of issues with this file.

- first, to be CF compliant, you'd need the following attribute:

               sst:coordinates = "latitude longitude" ;

to the sst variable for the CF Two-dimensional latitude, longitude 
coordinate system.

See:

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

- we do not support time varying latitude/longitude coordinates (and I
didn't see an example in the CF documentation listed above). If
you remove the time dimension, it gets closer to working.
 
- the latitude and longitude variables have the following attributes:

                latitude:add_offset = 0s ;
                latitude:scale_factor = 10s ;
                latitude:valid_range = -9000s, 9000s ;
                latitude:valid_min = -9000s ;
                latitude:valid_max = 9000s ;

and 

                longitude:add_offset = 0s ;
                longitude:scale_factor = 10s ;
                longitude:valid_range = -18000s, 17999s ;
                longitude:valid_min = -18000s ;
                longitude:valid_max = 17999s ;

which would scale the values by 10.  The values for latitude 
look like:

 latitude =
  59, 57, 57, 57, 57, 57, 57, 57, 57, 57, 57, 56, 56, 57, 57, 57, 57, 57, 57,
    57, 57, 56, 56, 56, 56, 56, 56, 56, 57, 56, 56, 56, 56, 56, 56, 56, 56,
    56, 56, 56, 56, 56, 56, 56, 55, 55, 55, 55, 56, 56, 55, 55, 55, 56, 56,
    54, 54, 55, 55, 55, 54, 55, 54, 54, 54, 55, 55, 55, 55, 54, 54, 54, 54,
    54, 54, 54, 54, 54, 54, 54, 53, 53, 53, 54, 54, 54, 54, 54, 54, 54, 53,

which seem like normal degrees, but if you multiply them by 10 (scale)factor,
they'll be outside the bounds of normal lat/lons.  If you remove the
scale factor, it's a little better, but...

- this does not appear to be a regular grid.  looking at the lat/lon
values, there is no regularity to the values.  In some cases, the
longitudes jump back and forth:

   145, 145, 144, 137, 144, 144, 145, 144, 145, 136, 138, 139, 145, 140,
   137, 139, 142, 138, 142, 137, 141, 142, 142, 138, 139, 143, 143, 138,
   141, 139, 142, 142, 142, 141, 138, 142, 137, 141, 141, 142, 141, 142,
   145, 141, 142, 142, 140, 141, 146, 146, 140, 141, 141, 141, 140, 142,

After making the changes above, I
can plot the data, but it's a wierd looking plot.  Is this truly a 
grid or is it really point data?

Let me know if you have more questions.

Don Murray

Ticket Details
===================
Ticket ID: DMJ-221042
Department: Support IDV
Priority: Normal
Status: Open