Re: [thredds] CF conventions for NetCDF metadata?

Hi Greg:

Greg Keith wrote:
-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1
The first part of this is not exactly a TDS question, but the second
part is...

We have had some recent complaints that the NetCDF data we serve using
THREDDS from http://www.cdc.noaa.gov/thredds/ cannot be imported
successfully into ArcGIS. In contrast to our installation, we are told
that the NetCDF files served from the NCDC NOMADS THREDDS server at
http://nomads.ncdc.noaa.gov/thredds/catalog/narr/catalog.html import
successfully.

I am wondering if the reason why is because the metadata in the NetCDF
files we serve using THREDDS adheres to the CF 1.0 conventions, and it
is lacking the more full-featured grid mapping attributes added in
later CF versions, specifically the "grid_mapping_name =
latitude_longitude" grid mapping I see documented in the CF 1.4
conventions
(http://cf-pcmdi.llnl.gov/documents/cf-conventions/1.4/cf-conventions.html#appendix-grid-mappings).

that sounds possible, though i dont really know what ArcGIS supports, and it likely depends on the version of ArcGIS. I understand it only supports a subset of CF projections, however.


However, I thought that if ArcGIS assumes the WGS-84 datum where
projection is not specified, it would default to lat/long when
importing the file...

The second part of this question IS a THREDDS-specific question - I
see, for example with the NCDCD NOMADS TDS NARR files (for example
http://nomads.ncdc.noaa.gov/thredds/ncss/grid/narr/200902/20090223/narr-b_221_20090223_0600_000.grb/dataset.html),
that NCDC is serving GRIB files and then using the NetCDF Subset
Service to allow the user to add required variables ("Add Lat/Lon to
file" may be the crucial piece missing in our setup for imports into
ArcGIS). However, I don't understand from looking at the NetCDF Subset
Service docs what enables this interface - is it a config setting in
TDS, more comprehensive metadata in the files we serve, both?
have a look here:

http://www.unidata.ucar.edu/projects/THREDDS/tech/reference/WCS.html

let me know if that answers it....
Thanks, Greg

- --
Greg Keith - Web System Administrator   greg.keith(-at-)noaa.gov
NOAA ESRL Physical Sciences Division  http://www.esrl.noaa.gov/psd
R/PSD, 325 Broadway, Boulder, CO         phone: 303-497-6645


-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.4.7 (MingW32)
iD8DBQFKb3v38IR34NeP2BwRAoVhAJ4m9WRhcBgwJFiNbDAkZ6AOprL9rgCeMBtZ
YmyR/++YTG4KdVwBDhw7jp0=
=uRHZ
-----END PGP SIGNATURE-----

_______________________________________________
thredds mailing list
thredds@xxxxxxxxxxxxxxxx
For list information or to unsubscribe, visit: http://www.unidata.ucar.edu/mailing_lists/



  • 2009 messages navigation, sorted by:
    1. Thread
    2. Subject
    3. Author
    4. Date
    5. ↑ Table Of Contents
  • Search the thredds archives: