[Met_help] NetCDF format

John Halley Gotway johnhg at rap.ucar.edu
Wed Sep 9 14:40:18 MDT 2009


Holly,

Sure thing.  Take a look in the directory METv2.0/out/pcp_combine for the
output of the PCP-Combine tool.  These were generated in by the MET test
scripts.  The NetCDF output from PCP-Combine is the format you should
copy.

The NetCDF format in METv2.0 is rather narrowly defined and wasn't
originally intended for this sort of use.  We're working to provide more
general support for NetCDF in the next release.

But as long as you make it look like the output of PCP-Combine, you should
be fine.  Here are a few pointers:

- Be sure to name the NetCDF data variables using the GRIB code
abbreviations listed in this table:
http://www.nco.ncep.noaa.gov/pmb/docs/on388/table2.html
   - Any spaces in the abbreviation in that table should be removed in the
variable name.
   - For accumulation intervals, append the number of accumulation hours
"_NN" to the variable name.  For example, 3-hours accumulated precip
would be APCP_03.

- Be sure to define all the variable attributes you see in the output of
PCP-Combine.  The "_ut" means unix time, the number of seconds since Jan 1
1970.  FYI, the command "date +%s" will give you the current unix time.

- Lastly, you need to define a bunch of global attributes that define the
grid on which the data resides.  The PCP-Combine output gives an example
of data on a Lambert Conformal grid.  If your data is on a different
projection, you could email me for help.  Or you could find a Grib file
that uses that type of projection, run it though PCP-Combine, and then
look at the global attributes to see how they're defined.

As I mentioned, we realize these conventions are overly restrictive. 
We're working to make it a lot easier to use NetCDF CF-convention data in
future releases of MET.

Thanks,
John
> Hello John-
>
>
>
> I hope this email finds you well.  We are hoping to convert one of our
> in-house models into NetCDF format so it can be read by Point Stat in
> MET.  Our first attempt gave us the following error:  "NetCDF:
> Attribute not found."
>
>
>
> Is there a sample NetCDF file you could send me so we have something to
> go off of?  Or a list of attributes/variables that must be defined in
> the files in order to be read by MET?
>
>
>
> Thank you!
>
> Holly
>
>
>
> ___________________________________
>
> Holly C. Hassenzahl
>
> Meteorologist, Science Analyst
>
> Data Products Group
>
>
>
> Weather Central, Inc.
>
> 401 Charmany Drive Suite 200
>
> Madison, WI 53711
>
> +1.608.274.5789
>
> +1.608.276.4600
>
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