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Hi Roy-While the NCDC NOMADS is a TDS provider ( http://nomads.ncdc.noaa.gov/thredds/catalog.html); we are not now providing Ocean models - however NODC is currently planning an "Ocean-NOMADS". Scott Cross is cc:ed herein. I believe that the Marine Modeling group is engaged in this discussion as well. Scott and Co, could use some user input I'm sure. Jordan Alpert tells me Avichal Mehra at NCEP will soon be standing up the OPeDNAP (gds) access to the RTOFS on the NOMADS server at NWS: http://nomads.ncep.noaa.gov/
Glenn Rich Signell wrote the following on 1/29/2009 7:40 AM:
Roy,Good thing you asked because we spent some time last summer scratching our heads over this one with the folks from NCEP!The RTOFS GRIB files represent an interesting case indeed, and the solution again shows the power of NcML. It also shows that we need a version of the THREDDS Data Server that uses NetCDF-Java 4.0.The problem is that RTOFS is a general curvilinear orthogonal grid (see http://coast-enviro.er.usgs.gov/models/share/2009-01-29_0717.png)that is not uniformly spaced in any map projection that can be specified analytically -- there is no GRIB code that can be used to determine the X,Y locations of the curvilinear grid cells. The RTOFS GRIB files specify "204", which was unknown to the NetCDF-Java 2.2.22, so it just stopped with an "unknown projection = 204" error. But with NetCDF-Java 4.0, it recognizes 204 as a "Curvilinear_Orthogonal_Grid". If you check out the NcML view of a RTOFS variable from the NetCDF tools app (-java -Xmx512m -jar toolsUI-4.0.jar), here's what you see:<variable name="Sensible_heat_net_flux" shape="time y x" type="float"> <attribute name="units" value="W m-2" /><attribute name="long_name" value="Sensible heat net flux @ surface" /><attribute name="missing_value" type="float" value="-9999.0" /> <attribute name="grid_mapping" value="Curvilinear_Orthogonal_Grid" /><attribute name="GRIB_param_discipline" value="Meteorological_products" /><attribute name="GRIB_param_category" value="Temperature" /> <attribute name="GRIB_param_name" value="Sensible_heat_net_flux" /> <attribute name="GRIB_param_id" type="int" value="2 0 0 11" /><attribute name="GRIB_product_definition_type" value="Analysis/forecast at horizontal level/layer" /><attribute name="GRIB_level_type" type="int" value="1" /> </variable>Of course, you still want to provide CF-compliant data via OpenDAP to your users, and the magic of NcML allows you to just union in a file that containst the lon and lat variables. So Avichal Mehra at NCEP kindly provided the lon/lat values and we made a NetCDF file that just contained those variables called "rtofs_lonlat.nc <http://rtofs_lonlat.nc>". So the NcML looks like:<netcdf xmlns="http://www.unidata.ucar.edu/namespaces/netcdf/ncml-2.2";> <aggregation type="union"> <netcdf location="shtfl.grib2"/> <netcdf location="rtofs_lonlat.nc <http://rtofs_lonlat.nc>"/> </aggregation> <variable name="Sensible_heat_net_flux"> <attribute name="coordinates" value="lon lat"/> <remove type="attribute" name="grid_mapping"/> </variable> <attribute name="Conventions" type="String" value="CF-1.0"/> </netcdf>If you want to try this out, you can grab these files (including grib and NcML) from:http://coast-enviro.er.usgs.gov/models/share/rtofs.zipUnfortunately, while the NcML works with NetCDF-Java 4.0, the current THREDDS Data Server does not yet use NetCDF-Java 4.0. As a work around for THREDDS using NetCDF-Java 2.22, you could modify ASCII .gbx file that get created when NetCDF-Java reads a grib file, replacing the unknown 204 code with something like "30". This will allow NetCDF-Java to continue without error, and it doesn't matter because the grid_mapping is not being used anyway.-RichOn Wed, Jan 28, 2009 at 4:09 PM, Roy Mendelssohn <Roy.Mendelssohn@xxxxxxxx <mailto:Roy.Mendelssohn@xxxxxxxx>> wrote:Hi All: Can THREDDS serve the RTOFS grib files? We are getting an error of unsupported coordinate system, get similar error within toolsUI. Is here something we need to ad to the setup to get it to work? Thanks, -Roy ********************** "The contents of this message do not reflect any position of the U.S. Government or NOAA." ********************** Roy Mendelssohn Supervisory Operations Research Analyst NOAA/NMFS Environmental Research Division Southwest Fisheries Science Center 1352 Lighthouse Avenue Pacific Grove, CA 93950-2097 e-mail: Roy.Mendelssohn@xxxxxxxx <mailto:Roy.Mendelssohn@xxxxxxxx> (Note new e-mail address) voice: (831)-648-9029 fax: (831)-648-8440 www: http://www.pfeg.noaa.gov/ "Old age and treachery will overcome youth and skill." "From those who have been given much, much will be expected"-- Dr. Richard P. Signell (508) 457-2229USGS, 384 Woods Hole Rd. Woods Hole, MA 02543-1598
-- Glenn K. Rutledge Meteorologist / Physical Scientist Team Lead Data Access Branch Climate Services Division NOMADS Project Manager National Oceanic and Atmospheric AdministrationNational Climatic Data Center 151 Patton Ave
Asheville NC 28801 Phone: (828) 271-4097 Fax: (828) 271-4876 NOMADS: http://nomads.ncdc.noaa.gov/
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