Ingest a New Grid

Unrecognized grids can be decoded by EDEX simply by dropping *.grib or *.grib2 files into /awips2/data_store/ingest/

To add support for a new grid, two edits must be made:

  • Geospatial projection must be defined in a grid navigation file
  • Grid name, center, subcenter, and process ID must be defined in a model definition file.

Ingest an Unsupported Grid

  1. Download an example grib1 file and rename to a *.grib extension, then copy to the manual ingest point /awips2/data_store/ingest/

    wget https://www.unidata.ucar.edu/staff/mjames/14102318_nmm_d01.GrbF00600 -O wrf.grib
    cp wrf.grib /awips2/data_store/ingest/

    Remember that the data distribution file (/awips2/edex/data/utility/edex_static/base/distribution/grib.xml) will match filename which have the *.grib extension.

  2. Confirm that the grib file decodes in the grib log file:

    edex log grib
    INFO [Ingest.GribDecode] /awips2/data_store/ingest/grib/20141026/14/wrf.grib processed in: 0.1200 (sec) Latency: 21.8080 (sec)
    INFO [Ingest.GribDecode] /awips2/data_store/ingest/grib/20141026/14/wrf.grib processed in: 0.1180 (sec) Latency: 21.8140 (sec)
    INFO [Ingest.GribDecode] /awips2/data_store/ingest/grib/20141026/14/wrf.grib processed in: 0.4230 (sec) Latency: 21.8360 (sec)
    INFO [Ingest.GribDecode] /awips2/data_store/ingest/grib/20141026/14/wrf.grib processed in: 0.2240 (sec) Latency: 21.9140 (sec)
  3. Check that the hdf5 data directory exists for our unnamed grid

    ls -latr /awips2/edex/data/hdf5/grid/GribModel:7:0:89

    Though the grib file has been decoded, it has been given a generic name with its center, subcenter, and process IDs (7, 0, 89, respectively).

Determine Grid Projection

When the grid was ingested a record was added to the grid_coverage table with its navigation information:

psql metadata

metadata=# select nx,ny,dx,dy,majoraxis,minoraxis,la1,lo1,lov,latin1,latin2 from gridcoverage where id=(select distinct(location_id) from grid_info where datasetid='GribModel:7:0:89');
 nx  | ny  |        dx        |        dy        | majoraxis | minoraxis |       la1        |        lo1        |        lov        |      latin1      |      latin2      
 201 | 155 | 4.29699993133545 | 4.29699993133545 |   6378160 |   6356775 | 42.2830009460449 | -72.3610000610352 | -67.0770034790039 | 45.3680000305176 | 45.3680000305176
(1 row)

Compare with the projection info returned by wgrib on the original file:

wgrib -V wrf.grib

rec 799:27785754:date 2014102318 ALBDO kpds5=84 kpds6=1 kpds7=0 levels=(0,0) grid=255 sfc 6hr fcst: bitmap: 736 undef
  ALBDO=Albedo [%]
  timerange 0 P1 6 P2 0 TimeU 1  nx 201 ny 155 GDS grid 3 num_in_ave 0 missing 0
  center 7 subcenter 0 process 89 Table 2 scan: WE:SN winds(grid) 
  Lambert Conf: Lat1 42.283000 Lon1 -72.361000 Lov -67.077000
      Latin1 45.368000 Latin2 45.368000 LatSP 0.000000 LonSP 0.000000
      North Pole (201 x 155) Dx 4.297000 Dy 4.297000 scan 64 mode 8
  min/max data 5 21.9  num bits 8  BDS_Ref 50  DecScale 1 BinScale 0

Notice that our grib1 file is a Lambert Conformal projection. We will need these values for the next step. Note that there is a tolerance of +/- 0.1 degrees to keep in mind when defining your coverage area.

Create Grid Projection File

Grid projection files are stored in /awips2/edex/data/utility/edex_static/base/grib/grids/ and there are four grid coverage types available:

  1. lambertConformalGridCoverage example

        <description>Regional - CONUS (Lambert Conformal)</description>
  2. polarStereoGridCoverage example

        <description>Sea Ice south 690X710 13km grid</description>
  3. latLonGridCoverage example

        <description>UKMet HiRes combined - Southern Hemisphere
            Longitude range 71.25E - 70.416E </description>
  4. mercatorGridCoverage example

        <description> National Blend Grid over Puerto Rico - (1.25 km)</description>

Copy an existing file file with the same grid projection type (in this case lambertConformalGridCoverage) to a new file wrf.xml

cd /awips2/edex/data/utility/edex_static/base/grib/grids/
cp RUCIcing.xml wrf.xml

And edit the new wrf.xml to define the projection values (example provided):

vi wrf.xml

    <description>Regional - CONUS (Lambert Conformal)</description>

Notice <name>201155</name> defined from the number of grid points (201 x 155). This value will be matched against an entry in our models file (below) to set the name of the model (e.g. WRF).

Create Model Definition

Model definition XML files are found in /awips2/edex/data/utility/edex_static/base/grid/models/. Since our grib1 file has a center ID of 7 (NCEP) we will edit the gribModels_NCEP-7.xml file.

cd /awips2/edex/data/utility/edex_static/base/grib/models/

vi gribModels_NCEP-7.xml

in <gribModelSet> add an entry


save the file and restart EDEX for the changes to take effect.

sudo service edex_camel restart

Now copy the wrf.grib file again to /awips2/data_store/ingest/. If everything is correct we will not see any persistence errors since the grid is now named WRF and not GribModel:7:0:89.

cp wrd.grib /awips2/data_store/ingest/

edex log grib

After you have confirmed that the grid was ingested with the given name, you can edit the D2D product menus to display the new grid.

Troubleshooting Grib Ingest

If you ingest a piece of data and the parameter appears as unknown in the metadata database, ensure that the correct parameter tables are in place for the center/subcenter.

Make sure the latitude and longitude entries in your coverage specification file match those of your ingested raw grib file. There is a tolerance of +/- 0.1 degree to keep in mind when defining your coverage area.

If some of the information is unknown, using a grib utility application such as wgrib and wgrib2 (not delivered) can be useful in determining the information that must be added to correctly process a new grib file.