NAGRIB converts gridded data in GRIB files to GEMPAK gridded data.

INPUT PARAMETERS
 
    GBFILE    GRIB data file name
    INDXFL    GRIB index file name
    GDOUTF    Output grid file
    PROJ      Map projection/angles/margins|drop flag
    GRDAREA   Area covered by grid
    KXKY      Number of grid points in x;y
    MAXGRD    Maximum number of grids
    CPYFIL    Grid file whose navigation is to be used in new grid file | subare
    GAREA     Graphics area
    OUTPUT    Output device/filename
    GBTBLS    Input GRIB decoding tables
    GBDIAG    GRIB diagnostic elements
    PDSEXT    Y or N, add PDS extension if found
    OVERWR    Overwr flag
 
 

PROGRAM DESCRIPTION
 
    NAGRIB will convert gridded data which is in GRIB files to
    gridded data in a GEMPAK file.

    The GRIB input file is specified in GBFILE, and the index
    file associated with the GRIB file is in INDXFL.

    The GEMPAK output file is given in GDOUTF. This file will
    be opened if it exists and the projection information
    matches the GRIB message projection. If the file does not
    exist, it will be created using information given by the
    user.  If the output filename is "LIST", the GRIB file will
    be scanned and the decoded GEMPAK header information will be
    printed out.

    The navigation information given by the user may take several
    forms. The first possibility is for the user to enter
    CPYFIL=#NNN, where NNN is a grid projection number listed in
    GRDNAV.TBL. Second, the user may enter CPYFIL=GDS. This will
    read the navigation from the Grid Definition Section of the
    first GRIB message. Third, the user could enter CPYFIL=OLDFILE,
    where OLDFILE is the name of an existing GEMPAK file from
    which to copy the navigation information. Last, the user
    may choose to use the PROJ, GRDAREA, and KXKY parameters to
    specify the navigation.

    GAREA is used to subset the grid.  It may be specified as
    any valid input for GAREA which are equivalent to lat/lon bounds
    or as a single @ followed by the lower-left and upper-right grid
    point coordinates separated by semicolons.  In the former case,
    the locations are rounded to the nearest grid points.  The
    projection type and angles entered as described above along with
    the lat/lon coordinates of the corners of the subset define a
    new grid navigation different from that of the full grid.  The
    navigation entered as described in the preceding paragraph is
    always that of the full grid.  To get the full grid, set GAREA to
    blank, GRID or DSET.

    OUTPUT defines the direction and destination of printed output.

    GBTBLS allows the user to override the default GRIB decoding tables
    by listing the filenames of the WMO and NCEP parameter tables,
    the vertical coordinate table and the originating center table.

    GBDIAG allows for detailed GRIB message section information,
    byte-by-byte, to be printed out for selected GRIB messages.
    Simply list those GRIB sections to be examined (IDS, PDS, GDS,
    BDS, BMS, END or ALL for all sections), e.g., pds;gds.
    Selected GRIB messages for examination may also be identified by
    number in list and/or range format, e.g., 2;4;5-9.

    PDSEXT is a logical flag which only becomes applicable when a PDS
    extension exists in the GRIB message. If PDSEXT is YES, then a
    sequence of characters specifying the extension information will be
    appended onto the standard GEMPAK parameter name.  If PDSEXT is NO,
    then the append will not be performed. For instance, if the parameter
    is HGHT and the PDS extension is an ensemble extension indicating that
    this particular height field is an ensemble mean average, then the PDS
    extension suffix will be "ENMA". The final GEMPAK parameter name
    will be "HGHTENMA" and must be referenced as such in any GEMPAK program.

    OVERWR is a logical flag that allows the user to overwrite the existing
    GEMPAK grid file.  If OVERWR is YES, then the grid file is being
    overwritten.  Otherwise, it remains the same.


EXAMPLES
 
    1.  Convert the data in the NGM GRIB file for 2 Sep 1993.
        Create the GEMPAK file using projection #105 from the
	grid navigation table.  Define a subset using lat/lon.


	GBFILE   =  ngm_930902_00_000.grib
	INDXFL   =
	GDOUTF   =  ngm_930902_00.grd
	PROJ     =
	GRDAREA  =
	KXKY     =
	MAXGRD   =  3000
	CPYFIL   =  #105
	GAREA    =  ks-
	OUTPUT   =  t


    2.  Convert the data in the MRF GRIB and INDEX files for
	2 Sep 1993. Create the GEMPAK file using the navigation
	information given the Grid Definition Section of the
	GRIB message.  Define a subset using grid coordinates.


	GBFILE   =  mrf_930902_00_000.grib
	INDXFL   =  mrf_930902_00_000.indx
	GDOUTF   =  mrf_930902_00.grd
	PROJ     =
	GRDAREA  =
	KXKY     =
	MAXGRD   =  3000
	CPYFIL   =  gds
	GAREA    =  @230;110;290;140
	OUTPUT   =  t


    3.  Convert the data in the GRIB file for North America. Create
	the GEMPAK file using the user input for PROJ, GRDAREA and
	KXKY.  Do not do a subset, use the full grid.


	GBFILE   =  north_amer.grib
	INDXFL   =
	GDOUTF   =  north_amer.grd
	PROJ     =  ced
	GRDAREA  =  0;-180;90;0
	KXKY     =  181;91
	MAXGRD   =  3000
	CPYFIL   =
	GAREA    =  grid
	OUTPUT   =  t


    4.  Convert the data in the GRIB file for the MESO model.
	Override the default decoding tables.


	GBFILE   =  /tmp/model/meso.mdl
	INDXFL   =
	GDOUTF   =  /tmp/model/meso.mdl.gem
	PROJ     =
	GRDAREA  =
	KXKY     =
	MAXGRD   =  3000
	CPYFIL   =  gds
	GAREA    =  grid
	OUTPUT   =  t
	GBTBLS   =  /tmp/wmogrib2.tbl;/tmp/nmcgrib2.tbl;/tmp/vcrdgrib1.tbl
	GBDIAG   =


    5.  Scan a GRIB file and print out the PDS and GDS sections
	for GRIB messages 1, 2, 6 through 12, and 88.


	GBFILE   =  ensemble.grib
	INDXFL   =
	GDOUTF   =  LIST
	PROJ     =  ced
	GRDAREA  =  0;-180;90;0
	KXKY     =  181;91
	MAXGRD   =  3999
	CPYFIL   =
	GAREA    =  grid
	OUTPUT   =  t
	GBTBLS   =
	GBDIAG   =  pds;gds|1;2;6-12;88


    6.  Convert the data in the GRIB file for the MESO model.
	Overwrite the existing GEMPAK grid file.


	GBFILE   =  /tmp/model/meso.mdl
	INDXFL   =
	GDOUTF   =  /tmp/model/meso.mdl.gem
	PROJ     =
	GRDAREA  =
	KXKY     =
	MAXGRD   =  3000
	CPYFIL   =  gds
	GAREA    =  grid
	OUTPUT   =  t
	GBTBLS   =
	GBDIAG   =
        OVERWR   = yes


ERROR MESSAGES
 
    [NAGRIB  +5]    GRIB version 0 cannot be decoded.
    [NAGRIB  +4]    Invalid parameter code table version.
    [NAGRIB  +3]    No valid parameter found for ....
    [NAGRIB  +2]    No valid vertical coordinate found for ....
    [NAGRIB  +1]    WARNING: This grid is too large for GEMPAK programs.
    [NAGRIB  -1]    Fatal error initializing TAE.
    [NAGRIB  -2]    Fatal error reading TAE parameters.
    [NAGRIB  -3]    Fatal error initializing GEMPLT.
    [NAGRIB  -4]    Navigation information is invalid.
    [NAGRIB  -5]    Grid area ... is invalid.
    [NAGRIB  -6]    Grid size is invalid.
    [NAGRIB  -7]    The grid file name may not be blank.
    [NAGRIB  -8]    Navigation table cannot be read.
    [NAGRIB  -9]    Grid name ... cannot be found in grid table.
    [NAGRIB -10]    Input for GEMPAK output file is blank.
    [NAGRIB -11]    Error opening GEMPAK grid file.
    [NAGRIB -12]    Error creating GEMPAK grid file.
    [NAGRIB -13]    Cannot open GRIB vertical coordinate table.
    [NAGRIB -14]    Cannot open GRIB parameter table.
    [NAGRIB -15]    Error opening GRIB file.
    [NAGRIB -16]    Error getting next message.
    [NAGRIB -17]    Error setting date/time.
    [NAGRIB -18]    Invalid bitmap specification.
    [NAGRIB -19]    Error reading GRIB file.
    [NAGRIB -20]    Invalid input for GAREA.
    [NAGRIB -21]    Grid is too large.
    [NAGRIB -22]    Length of BDS section less than or equal to 0