Re: GRIB to netCDF (fwd)

John, et al

I used the example grib file that was send to test the decoders packeage,
the bugs were  very apparent.  The bugs were fixed and I also update the
gribdump program to use the -g flag ( user params table ) and updated the
gribtonc and gribdump  man pages.  The table file that was sent had a
error, the name of  a NetCDF variable name cannot start with a digit, so I
created another one. ie,


        Grib;netCDF;long name               ;units;comments
        167 ;T_2meter     ;2 metre temperature     ;K    ;
        228 ;precep_total ;Total precipitation     ;m    ;

The ecmf.tbl and eecmf.cdl file are included as attachments.

There is a new decoders release with the fixes: decoders-2.4.3.tar.Z

%ftp www.unidata.ucar.edu

login as anonymous

% cd pub/decoders
% get decoders-2.4.3.tar.Z

There is more documentation on the decoders page at:

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

Robb...

>
> Date:    Thu, 20 Feb 2003 10:45:58 -0500
> From:    "John A. Dutton" <address@hidden>
> To:      address@hidden
> cc:      address@hidden, address@hidden
> Subject: GRIB to netCDF
>
> Hi Russ..
>
> It seems I have a flood of questions after years of silence...
>
> Thanks for your prompt reply on Monday.  I got the SST data I needed
> via a direct compile and execution of a little program via gcc, but I
> still have not gotten the library to work in Code Warrior.  I sent a
> message to Metrowerks...we'll see if I get an answer.
>
> New problem: We are encountering difficulties in trying to convert
> ECMWF GRIB files of  ensemble seasonal forecasts to netCDF.   The
> issue seems to turn on the fact that the  Unidata gribtocdl utilities
> are using the NCEP GRIB
> parameter tables and that there are differences with ECMWF.
>
> Any information or assistance would be greatly appreciated.
>
> Please REPLY to ALL since Ben Hauger above is actually doing the work.
>
> Again, many thanks, John
> --
> John A. Dutton
> Professor of Meteorology and Dean Emeritus
> College of Earth and Mineral Sciences
> The Pennsylvania State University
> 814 865 1534
>
> ------- End of Forwarded Message
>
>

===============================================================================
Robb Kambic                                Unidata Program Center
Software Engineer III                      Univ. Corp for Atmospheric Research
address@hidden             WWW: http://www.unidata.ucar.edu/
===============================================================================

        Grib;netCDF;long name               ;units;comments
        167 ;T_2meter     ;2 metre temperature     ;K    ;
        228 ;precep_total ;Total precipitation     ;m    ;

netcdf WVL_ECMWF_SEAS_20030201_1_GB{ 


dimensions:
        record = UNLIMITED ;    // (reference time, forecast time)
        lat = 91 ;
        lon = 240 ;
        datetime_len = 21 ;
        nmodels = 2 ;
        ngrids = 1 ;
        nav = 1 ;
        nav_len = 100 ;

variables:

        double reftime(record) ;        // reference time of the model
               reftime:long_name = "reference time" ;
               reftime:units = "hours since 1992-1-1" ;

        double valtime(record) ;        // forecast time ("valid" time)
               valtime:long_name = "valid time" ;
               valtime:units = "hours since 1992-1-1" ;

        :record = "reftime, valtime" ;  // "dimension attribute" -- means
                                        // (reftime, valtime) uniquely
                                        // determine record

        char   datetime(record, datetime_len) ; // derived from reftime
               datetime:long_name = "reference date and time" ;
               // units YYYY-MM-DD hh:mm:ssZ  (ISO 8601)

        float  valtime_offset(record) ; // derived as valtime-reftime
               valtime_offset:long_name = "hours from reference time" ;
               valtime_offset:units = "hours" ;


        // The following lat and lon coordinate variables are redundant,
        // since the navigation variables provide the necessary information.
        // The extra information is included here for human readability.

        float  lat(lat) ;
               lat:long_name = "latitude" ;
               lat:units = "degrees_north" ;

        float  lon(lon) ;
               lon:long_name = "longitude" ;
               lon:units = "degrees_east" ;

        long   model_id(nmodels) ;
               model_id:long_name = "generating process ID number" ;

        // navigation variables all use nav dimension

        char   nav_model(nav, nav_len) ;        // navigation parameterization
               nav_model:long_name = "navigation model name" ;

        int    grid_type_code(nav) ;
               grid_type_code:long_name = "GRIB-1 GDS data representation type" 
;

        char   grid_type(nav, nav_len) ;
               grid_type:long_name = "GRIB-1 grid type" ;

        char   grid_name(nav, nav_len) ;
               grid_name:long_name = "grid name" ;

        int    grid_center(nav) ;
               grid_center:long_name = "GRIB-1 originating center ID" ;

        int    grid_number(nav, ngrids) ;
               grid_number:long_name = "GRIB-1 catalogued grid numbers" ;
               grid_number:_FillValue = -9999 ;

        char   i_dim(nav, nav_len) ;
               i_dim:long_name = "longitude dimension name" ;

        char   j_dim(nav, nav_len) ;
               j_dim:long_name = "latitude dimension name" ;

        int    Ni(nav) ;
               Ni:long_name = "number of points along a latitude circle" ;

        int    Nj(nav) ;
               Nj:long_name =        "number of points along a longitude 
circle" ;

        float  La1(nav) ;
               La1:long_name = "latitude of first grid point" ;
               La1:units = "degrees_north" ;

        float  Lo1(nav) ;
               Lo1:long_name = "longitude of first grid point" ;
               Lo1:units = "degrees_east" ;

        float  La2(nav) ;
               La2:long_name = "latitude of last grid point" ;
               La2:units = "degrees_north" ;

        float  Lo2(nav) ;
               Lo2:long_name = "longitude of last grid point" ;
               Lo2:units = "degrees_east" ;

        float  Di(nav) ;
               Di:long_name = "Longitudinal direction increment" ;
               Di:units = "degrees" ;

        float  Dj(nav) ;
               Dj:long_name = "Latitudinal direction increment" ;
               Dj:units = "degrees" ;

        byte   ResCompFlag(nav) ;
               ResCompFlag:long_name = "resolution and component flags" ;

        // end of navigation variables

        float  T_2meter_sfc(record,lat,lon) ;
               T_2meter_sfc:long_name = "2 metre temperature" ;
               T_2meter_sfc:units = "K" ;
               T_2meter_sfc:_FillValue = -9999.f ;
               T_2meter_sfc:navigation = "nav" ;

        float  precep_total_sfc(record,lat,lon) ;
               precep_total_sfc:long_name = "Total precipitation" ;
               precep_total_sfc:units = "m" ;
               precep_total_sfc:_FillValue = -9999.f ;
               precep_total_sfc:navigation = "nav" ;


// global attributes
               :history = "2003-02-21 14:47:11 - created by gribtocdl 1.4 - 
12.12.2002" ; 
               :title = "WVL_ECMWF_SEAS_20030201_1_GB" ;
               :Conventions = "NUWG" ;
               :version = 0.0 ;

data:

 model_id = 199, 152 ;

 // Navigation
 nav_model = "GRIB1" ;
 grid_type_code = 0 ;
 grid_type = "Latitude/Longitude" ;
 grid_name = " " ;
 grid_center = 98 ;
 grid_number = 255 ;
 i_dim = "lon" ;
 j_dim = "lat" ;
 Ni = 240 ;
 Nj = 91 ;
 La1 = -60.000000 ;
 Lo1 = 0.000000 ;
 La2 = 75.000000 ;
 Lo2 = 358.500000 ;
 Di = 1.500000 ;
 Dj = 1.500000 ;
 ResCompFlag = 128 ;

 lon =  0.00,  1.50,  3.00,  4.50,  6.00,  7.50,  9.00, 10.50,
       12.00, 13.50, 15.00, 16.50, 18.00, 19.50, 21.00, 22.50,
       24.00, 25.50, 27.00, 28.50, 30.00, 31.50, 33.00, 34.50,
       36.00, 37.50, 39.00, 40.50, 42.00, 43.50, 45.00, 46.50,
       48.00, 49.50, 51.00, 52.50, 54.00, 55.50, 57.00, 58.50,
       60.00, 61.50, 63.00, 64.50, 66.00, 67.50, 69.00, 70.50,
       72.00, 73.50, 75.00, 76.50, 78.00, 79.50, 81.00, 82.50,
       84.00, 85.50, 87.00, 88.50, 90.00, 91.50, 93.00, 94.50,
       96.00, 97.50, 99.00,100.50,102.00,103.50,105.00,106.50,
      108.00,109.50,111.00,112.50,114.00,115.50,117.00,118.50,
      120.00,121.50,123.00,124.50,126.00,127.50,129.00,130.50,
      132.00,133.50,135.00,136.50,138.00,139.50,141.00,142.50,
      144.00,145.50,147.00,148.50,150.00,151.50,153.00,154.50,
      156.00,157.50,159.00,160.50,162.00,163.50,165.00,166.50,
      168.00,169.50,171.00,172.50,174.00,175.50,177.00,178.50,
      180.00,181.50,183.00,184.50,186.00,187.50,189.00,190.50,
      192.00,193.50,195.00,196.50,198.00,199.50,201.00,202.50,
      204.00,205.50,207.00,208.50,210.00,211.50,213.00,214.50,
      216.00,217.50,219.00,220.50,222.00,223.50,225.00,226.50,
      228.00,229.50,231.00,232.50,234.00,235.50,237.00,238.50,
      240.00,241.50,243.00,244.50,246.00,247.50,249.00,250.50,
      252.00,253.50,255.00,256.50,258.00,259.50,261.00,262.50,
      264.00,265.50,267.00,268.50,270.00,271.50,273.00,274.50,
      276.00,277.50,279.00,280.50,282.00,283.50,285.00,286.50,
      288.00,289.50,291.00,292.50,294.00,295.50,297.00,298.50,
      300.00,301.50,303.00,304.50,306.00,307.50,309.00,310.50,
      312.00,313.50,315.00,316.50,318.00,319.50,321.00,322.50,
      324.00,325.50,327.00,328.50,330.00,331.50,333.00,334.50,
      336.00,337.50,339.00,340.50,342.00,343.50,345.00,346.50,
      348.00,349.50,351.00,352.50,354.00,355.50,357.00,358.50 ;

 lat =-60.00,-58.50,-57.00,-55.50,-54.00,-52.50,-51.00,-49.50,
      -48.00,-46.50,-45.00,-43.50,-42.00,-40.50,-39.00,-37.50,
      -36.00,-34.50,-33.00,-31.50,-30.00,-28.50,-27.00,-25.50,
      -24.00,-22.50,-21.00,-19.50,-18.00,-16.50,-15.00,-13.50,
      -12.00,-10.50, -9.00, -7.50, -6.00, -4.50, -3.00, -1.50,
        0.00,  1.50,  3.00,  4.50,  6.00,  7.50,  9.00, 10.50,
       12.00, 13.50, 15.00, 16.50, 18.00, 19.50, 21.00, 22.50,
       24.00, 25.50, 27.00, 28.50, 30.00, 31.50, 33.00, 34.50,
       36.00, 37.50, 39.00, 40.50, 42.00, 43.50, 45.00, 46.50,
       48.00, 49.50, 51.00, 52.50, 54.00, 55.50, 57.00, 58.50,
       60.00, 61.50, 63.00, 64.50, 66.00, 67.50, 69.00, 70.50,
       72.00, 73.50, 75.00 ;

}