Re: decoders] Grib File Data Extraction

On Fri, 1 Aug 2008, Don McGregor wrote:

> I'm looking for some examples of extracting data from grib files using
> the Java decoders.
> The Grib1Dump utility shows the output at the bottom of this message.
> However, when I
> load the file using the code below, I get zero records. I'm new to
> grib files, and my understanding
> is that there should be a record for each parameter.


Hiya,

GribDump is just to dump the headers of the Grib files, most Grib data is 
large so we use the index approach and a utility GribGetData ie

Grib(1|2)Indexer to index the records in the Grib file


# Grib(1|2)GetData to extract the data on a parameter basis.
# Parameter and level lookup routines. See Parameters

on the page:

http://www.unidata.ucar.edu/software/decoders/

there are Java docs that explain the routines in detail and what 
parameters to use.

Robb...


>               ucar.unidata.io.RandomAccessFile raf = new
> ucar.unidata.io.RandomAccessFile("data/seaTemp1","r");
>               Grib1Input gribInput = new Grib1Input(raf);
>               System.out.println("GRIB version is " +
> gribInput.getEdition());
>
>               List records = gribInput.getRecords();
>               System.out.println("Number of records is " +
> records.size());
>
> Dump of the GRIB file:
>
>                         Header : GRIB1
>                     Discipline : 0 Meteorological Products
>                   GRIB Edition : 1
>                    GRIB length : 390002
>             Originating Center : 58 U.S. Navy Fleet Numerical
> Meteorology and Oceanography Center
>         Originating Sub-Center : 0 WMO Secretariat
>             Product Definition : 0 Forecast/Uninitialized Analysis/
> Image Product
>             Parameter Category : -1 Meteorological Parameters
>                 Parameter Name : 80 var80 temperature of sea  water
>                Parameter Units : deg_K
>                 Reference Time : 2008-07-30T12:00:00Z
>                     Time Units : hour
>           Time Range Indicator : product valid at RT + P1
>                    Time 1 (P1) : 0
>                    Time 2 (P2) : 0
>        Generating Process Type : 78 126 wave triangular, 28 layer
> Spectral model from Medium Range Forecast run
>                     Level Type : 1 surface
>                  Level Value 1 : 0.0
>                  Level Value 2 : 0.0
>                     GDS Exists : true
>                     BMS Exists : false
>          Number of data points : 259920
>                      Grid Name : Latitude/Longitude Grid
>                      Grid Shape: 0 spherical
>          Spherical earth radius: 6367.47
>                             Nx : 720
>                             Ny : 361
>                            La1 : -90.0
>                            Lo1 : 0.0
>   Resolution & Component flags : 128
>                          Winds : Relative
>                            La2 : 90.0
>                            Lo2 : -0.5
>                             Dx : 0.5
>                             Dy : 0.5
>                  Scanning mode : 64
>
>
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===============================================================================
Robb Kambic                                Unidata Program Center
Software Engineer III                      Univ. Corp for Atmospheric Research
address@hidden             WWW: http://www.unidata.ucar.edu/
===============================================================================