OpenDAP GRIB Retrieval from Nomads

[Wesley Ebisuzaki]

Mark,

    http://nomads.ncep.noaa.gov is the operational NCEP nomads site.
Since you
want a regional subset, I am assuming that you want to minimize
time/bandwidth.
Downloading grib2 is good because grib-2 is compressed data. You will
save time
over DODS which transfers the data as a text file. You will also save
time because
GDS has considerable overhead on the server.   Once you have obtained
the grib-2 data,
you can use g2ctl to create the control file.

Example of grib2 compression:
   1x1 degree GFS hgt 500mb:  4.6 bits per grid point
    text file: several characters per grid point.

Two ways to download the grib data.

   (1) downloading the appropriate grib fields by partial http downloading.

http://www.cpc.noaa.gov/products/wesley/fast_downloading_grib.html
            http://www.cpc.noaa.gov/products/wesley/get_gfs.html
          use "http" option to find the URLs.  See the main page
(http://nomads.ncep.noaa.gov)

    (2) creating regional subsets of the grib2 files, use "grib filter"
(aka g2sub) from
       the main page.

            Wesley Ebisuzaki


Mark Hess wrote:
> All,
>
> I tried to search the GRADSUSR archives for the answer to this
> question, but it gives me the error errno=146 "unable to initiate
> communication...".  Perhaps you all can offer an answer.
>
> Does anyone have any sample strings for use with gradsdods to retreive
> a GFS grib file from the NWS NCEP MOMANDS OpenDAP server?
> (http://nomads.ncep.noaa.gov:9090/dods/gfs)
>
> I'm especially interested in how to extract data for a specified
> geographical region.
>
> If anyone can get me started with this, I should be able to take an
> example and work from there.
>
> Thank you.
>
> Mark
>