1GRIBTONC(1) General Commands Manual GRIBTONC(1)
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6 gribtonc - GRIB to netCDF decoder
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9 gribtonc [-l logpath] [-v] [-t timeout] [-e errpath]
10 [-g userparams.tbl] [-q qspecs] CDL_path netCDF_path
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13 This program decodes GRIB products (embedded in WMO product envelopes)
14 on the NWS High-Resolution Data Service (HRS) feed, writing the decoded
15 products into a single netCDF output file, specified by netCDF_path.
16 In case the output netCDF file does not already exist, the CDL_path
17 must be supplied to specify the structure for the desired netCDF file,
18 which gribtonc creates. The default parameter translation is made ac‐
19 cording to a definition by UCAR, but the user may supply specific
20 translations in a separate file by the -g tabfile option. The user-sup‐
21 plied translations will override the default ones. GRIB products are
22 converted to the units specified for the appropriate netCDF variable,
23 if this differs from the units used for the GRIB parameter. A set of
24 CDL files for all the model outputs appearing on the HRS data stream is
25 provided with gribtonc for use in decoding HRS GRIB data.
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28 The format of the translation table is as follows: Each line contains
29 GRIB parameter number
30 netCDF parameter name (cannot start with digit, [A-Za-z0-9_] only )
31 netCDF long description
32 netCDF units
33 An optional comment
34 These are all separated by semicolon (";"). To comment a whole line,
36 put any letter or special character (i.e. not a digit) in front of it.
37 Trailing spaces are ignored before each semicolon, but not after. The
38 GRIB number may have spaces in front. Parameters found in the separate
39 file take presidence over the default parameter table, those not listed
40 in the separate file are unchanged. All parameters will be named with
41 a level suffix in addition to the name assigned in the separate file.
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45 The command
46 gribtocdl -v -g my.tab sst.grib > sst.cdl
47 will decode the products in sst.grib and generate the corresponding CDL
49 code into file sst.cdl. The file my.tab contains a specific conversion
50 table to be used when naming a parameter from GRIB. Later the GRIB
51 file may be converted to netCDF by using gribtonc:
52 gribtonc -v -g my.tab sst.cdl sst.nc < sst.grib
53 The file my.tab looks like this:
55 Grib;netCDF;long name ;units;comments
56 31 ;CI ;Sea-ice cover ;none ;(0-1)
57 34 ;SSTK ;Sea surface temperature ;K ;
58 151 ;MSL ;Mean sea-level pressure ;Pa ;
59 167 ;T2M ;2 metre temperature ;K ;
60 gribtonc can run as a subprocess of the LDM pqact(1) program, receiving
62 a stream of GRIB products from standard input and decoding them as they
63 arrive. gribtonc can also be used as a standalone decoder, decoding
64 products on its standard input into netCDF form, as specified by
65 netCDF_file GRIB products that do not conform to the specified file
66 structure (e.g. they are defined on a different grid or contain a grid
67 parameter not included in the specified netCDF file) are skipped.
68 To use gribtonc from the LDM pqact(1) program requires adding entries
70 to the pqact configuration file that invoke gribtonc on appropriate HRS
71 products. The PIPE action should be used in pattern-action entries.
72 The form of such an entry is:
73 HRS pattern PIPE gribtonc-executable
76 gribtonc-options cdl-
77 file netcdf-file
78 where pattern is a regular expression pattern matching product identi‐
80 fiers of products that are to be decoded and written to the output file
81 netcdf-file.
82 Any directories that do not exist in netcdf-file will be created as
84 needed, so date components, for example, may be part of the output file
85 path, specified by using matched parts of the regular expression pat‐
86 tern. In case the output netcdf-file does not already exist, it will
87 be created from the CDL specification in the file specified by cdl-
88 file.
89 The path of the executable for gribtonc must be specified as the first
91 argument to the PIPE command, and should be either an absolute path
92 name or in a directory in the executable search path of pqact.
93 An example pqact.conf entry for decoding GRIB products from the ETA
95 model as they appear on the HRS data stream is:
96 # ETA model on Lambert conformal grid to yyyymmddhh_eta.nc HRS ^Y.Q...
98 KWBC (..)(..).*/mETA PIPE /usr/local/ldm/decoders/gribtonc
99 etc/eta.cdl data/GRIB/(1:yyyy)(1:mm)12_eta.nc
100 Since gribtonc reads GRIB products from its standard input, it may be
102 invoked independently of pqact(1) by using I/O redirection.
103
105 -l logpath
106 Log file pathname. The program uses Unidata's ulog(3) package
107 to write error and log messages. The default is to write to the
108 syslogd(8) daemon. If this option is specified, however, then
109 messages will be written to the file logpath unless that path‐
110 name is "-", in which case all messages will be written to stan‐
111 dard error.
112 -v Verbose logging. Informative messages (level LOG_INFO) are
114 logged, including a line for each GRIB product decoded. By de‐
115 fault, only messages of severity LOG_NOTICE and greater are
116 logged.
117 -t timeout
119 Timeout in seconds (default is 600). If there has been no input
120 available on stdin for the duration of the specified timeout,
121 the program exits gracefully.
122 -e errpath
124 If a GRIB product cannot be decoded, perhaps because it is trun‐
125 cated or otherwise corrupted, it is appended to this file.
126 -g tabfile
128 Use GRIB-netcdf translation defined in this file. The format of
129 this file is described below.
130 -q qspecs
132 Specification for how to expand so-called quasi-regular or
133 thinned grids into rectangular grids. This argument is a comma-
134 delimited text string that specifies the method of interpolation
135 used (currently lin for linear or cub for cubic), and the lati‐
136 tude and longitude increments in degrees for the resulting grid
137 (e.g. dlat=2.5,dlon=5.0).
138 CDL_path
140 The path name of a file to be used as a template for the netCDF
141 file, if the netCDF file specified as output does not exist. If
142 the netCDF output file does exist, this argument is ignored. A
143 path name relative to the directory specified by the LDM_ETCDIR
144 environment variable may be used, but you must make sure this
145 environment variable is defined in gribtonc
146 netCDF_path
148 The path name of the netCDF output file. This may be specified
149 as an absolute path name or (more typically) relative to the di‐
150 rectory from which gribtonc is invoked. Directories that do not
151 exist in the path name of the output file will be created as
152 needed.
153
156 The command
157 gribtonc -v -l- -q "lin,dlat=2.5,dlon=5.0" avn-x.cdl avn-x.nc < avn-x.wmo
158 will decode the products in avn-x.wmo into the netCDF file avn-x.nc,
159 creating the latter file if it does not already exist from the ASCII
160 CDL template file avn-x.cdl. If the data contain quasi-regular grids,
161 they will be expanded to full regular grids on a 2.5 by 5.0 degree grid
162 before being written into the output file.
163
165 gribdump(1), netcdf(3), pqact(1), udunits(3), ulog(3)
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168 Error messages and log messages are written to the log file.
169 8 June 1995 GRIBTONC(1)