APPENDIX GRIB data

Because of the complexity of GRIB data and the fact that it is not fully supported by Digital Atmosphere yet, Weather Graphics Technologies will not provide assistance in locating, retrieving, or using GRIB data.  It is provided as-is.  Comments are welcomed but we may not be able to respond to questions. If you need help, please access our public discussion group on our website at www.weathergraphics.com

The majority of GRIB output data is available from supercomputer models, such as the ETA model output provided by the National Center for Environmental Prediction near Washington DC. Sources of data include:

• ftp://140.90.88.142
• http://weather.noaa.gov/pub/SL.us008001/ST.opnl/      - Choose the .grl directories. Within these, try to choose the smallest datasets, as even the smallest ones will contain a vast amount of data. The larger ones may crash Digital Atmosphere. A good dataset usually ends in awp211. These are GRIB sets but will not have a *.grb extension. To get them to show up you will need to change the filetype to "AWIPS" or "all" when choosing a GRIB file to import.
• http://nomad3.ncep.noaa.gov/   (new as of 2006)
• http://www.globalmarinenet.net/grib.htm
• http://www.ecmwf.int/products/realtime/d/gts/essential/
  

Documentation for the GRIB format includes:

http://www.nws.noaa.gov/dataprod.html

http://205.156.54.206/oso/ftpgenl.shtml

http://zephyr.unl.edu/grids/

http://www.ncep.noaa.gov/NCO/PMB/docs/on388/tablea.html (MMM model codes)

http://www.ncep.noaa.gov/NCO/PMB/docs/on388/tableb.html (grids with pole point listings)

http://www.comet.ucar.edu/strc/data/model_data_summaries/ (lists grids w/ images and model codes in current use)

http://www.comet.ucar.edu/strc/data/model_data_summaries/osoname.html (GRIB naming conventions)

http://dss.ucar.edu/docs/formats/grib/gribdoc.pdf (Complete documentation)

http://weather.unisys.com/wxp/Appendices/Formats/GRIB.html (more documentation)

http://weather.unisys.com/wxp/File/Model_Name.html

http://www.cgd.ucar.edu/cms/eaton/cf-metadata/ECMWF.html

 

Since 2002, the NWS has used a hierarchichal naming convention that forms a URL. An example is:
  http://weather.noaa.gov/pub/SL.us008001/ST.opnl/MT.eta_CY.00/RD.20031009/PT.grid_DF.gr1/fh.0000_tl.press_gr.awp211

This shows that at the central server location (SL.us008001), one can find operational status data (ST.opnl) consisting of the Eta 00Z cycle model (MT.eta_CY.00) produced on 09 Oct 2003 (RD.20031009). Within this one can find GRIB data (PT.grid_DF.gr1) consisting of data for the 00h forecast hour mapped onto the AWIPS 211 grid (fh.0000_tl.press_gr.awp211).

For more information on this naming convention see
   http://www.nws.noaa.gov/datamgmt/filstnd.html (Directory and File Naming Standards)
and
   http://www.nws.noaa.gov/datamgmt/tgftp_file_reference.html (TGFTP File Reference).
Information on grids is at
   http://wwwt.emc.ncep.noaa.gov/mmb/etagrids/

The legacy filename format for NWS GRIB data is as follows. Some datasets can still be found in the top-level directory at http://weather.noaa.gov/pub/ which use this filename convention.

Sample: us008_gf000_02020300_HxXAx

Portions: us008_gfMMM_YYMMDDHH_ADGT

Here is what each field means:

MMM - Model code. Underlined codes are in current use as of February 2002; others are obsolete and are listed only for historical purposes. 000=Experimental, 010=GlobalWindWave, 039=NGM, 044=SeaSfcTemp, 076=MRFbiascorrected, 077=AVNfcst, 078=MRF, 080=MRF, 081=AVNinit, 082=MRFinit, 083=ETA80km, 084=ETA22km, 085=ETA29km, 086=RUC60km, 089=ETA48km, 094=MRF-T170/L42, 096=AVNfcst-T170/L42, 121=WesternNorthAtlanticwavemodel, 122=AlaskaWatersRegWaveModel, 130=MergeOfRucEtaSpectral.

YYMMDDHH - Year, month, date, and hour - of model start time.

A - GRIB designator - H=WAFS (Family Of Services), Y=AWIPS, Z=AWIPS.

D - Data type. X=mixture.

G - Grid. A=201 (Nhem/PS), H=213 (US/PS), I=202 (US/PS), J=203 (Alaska/PS), K=204 (Hawaii/MER), L=205 (PuertoRico/PS), M=206 (CentralUS/LAM), N=207 (Alaska/PS), O=208 (Hawaii/MER), P=210 (PuertoRico/MER), Q=211 (US/LAM), R=212 (US/LAM), T=214 (Alaska/PS), U=215 (US/LAM), V=216 (Alaska/PS), X=experimental. Code following the geographical area means PS=Polar Stereographic, LAM=Lambert Conformal, MER=Mercator.

T - Timestamp. A=00, B=06 C=12, D=18, E=24, F=30, G=36, H=42, I=48, J=60, K=72, L=84, M=96, N=108, O=120, P=132, Q=144, R=156, S=168, T=180, U=192, V=204, W=216, X=228, Y=240. However if "A" (GRIB designator) is Z (AWIPS), this will instead be A=02, B=03, C=04, D=08, etc.

Note that Digital Atmosphere will only process grids mapped in lat/long, polar stereographic, and lambert conformal projections