About GRIB File
If you are a Meteorologist or Climate Scientist or Engineer working on a forecast or Reanalysis data set, you would have probably come across the grib file format. It is a shortened name for “General Regularly distributed Information in Binary form” which is a WMO standard for storing and transferring gridded datasets. The gridded datasets may be forecast data from Atmospheric, Ocean, or Climatology models. The GRIB files may have extensions like ‘.grib2’, ‘.grib’, ‘grb’, or ‘.gb’ and in some cases, it may not even have a file name extension.
There are mainly two types of GRIB file formats i.e. GRIB1 and GRIB2. Some info on the GRIB file format may be referred to here at https://confluence.ecmwf.int and here at https://weather.gc.ca.
About wgrib2
wgrib2 is one of the most versatile and fast tools available for reading and manipulating GRIB2 gridded datasets. For complete technical documentation, you may refer https://www.nco.ncep.noaa.gov/pmb/docs/grib2/grib2_doc/. The official documentation is available at https://www.nco.ncep.noaa.gov. Some of the frequently used options with examples are listed at https://www.ftp.cpc.ncep.noaa.gov/wd51we/wgrib2/tricks.wgrib2. Since this post is not about working with wgrib2, I will go ahead and install the package now.
Install wgirb2 on Linux
This guide is on how to install wgrib2 on a Ubuntu OS. A guide for Windows users is given at the end of this article.
Firstly, update the OS before proceeding further:
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sudo apt-get update && apt-get upgrade
Install all necessary dependencies on Ubuntu and its derivatives:
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sudo apt-get install -y build-essential libaec-dev zlib1g-dev libcurl4-openssl-dev libboost-dev curl wget zip unzip bzip2 gfortran gcc g++
If you use Redhat or its derivatives, use the following commands:
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sudo groupinstall "Development Tools"
sudo dnf install gcc-gfortran csh perl
Make a working directory for compilation and move into it:
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mkdir -p ~/Downloads/wgrib2
cd ~/Downloads/wgrib2
Download the latest source code and extract it to the current working directory:
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wget -c ftp://ftp.cpc.ncep.noaa.gov/wd51we/wgrib2/wgrib2.tgz
tar -xzvf wgrib2.tgz
Move to the grib2 directory where all the necessary compilation files are located:
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cd grib2
Compile the source code:
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make
Note that it does not require configure as we do for many of the source compilations. If everything goes well, you should have compiled the wgrib2 executable under the wgrib2 directory. Check if it is properly compiled using the following command:
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wgrib2/wgrib2 -config
which should print information like the below:
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wgrib2 v3.1.1 4/2022 Wesley Ebisuzaki, Reinoud Bokhorst, John Howard, Jaakko Hyvätti, Dusan Jovic, Daniel Lee, Kristian Nilssen, Karl Pfeiffer, Pablo Romero, Manfred Schwarb, Gregor Schee, Arlindo da Silva, Niklas Sondell, Sam Trahan, George Trojan, Sergey Varlamov
Compiled on 14:16:59 Jan 10 2023
Netcdf package: 4.8.1 of Oct 31 2022 22:16:44 $ is installed
hdf5 package: system is installed
Jasper 2.0.33 is installed
mysql package is installed
regex package is installed
flush_mode determined by stat()
tigge package is installed
interpolation package is not installed, default vectors:
UGRD/VGRD VUCSH/VVCSH UFLX/VFLX UGUST/VGUST USTM/VSTM VDFUA/VDFVA MAXUW/MAXVW
UOGRD/VOGRD UICE/VICE U-GWD/V-GWD USSD/VSSD
Geolocation library status (by search order)
gctpc geolocation is enabled
spherical geolocation is enabled
UDF package is not installed
version ftime=2
maximum number of arguments on command line: 10000
maximum number of -match,-not,-if, and -not_if options: 2000
maximum number of -match_fs,-not_fs,-if_fs, and -not_if_fs options: 2000
maximum number of -fgrep, -egrep, -fgrep_v, -egrep_v options: 200
RPN registers: 0..19
memory files: @mem:0, @mem:1 .. @mem:29
stdout buffer length: 100000
default decoding: g2clib emulation
g2clib decoders are not installed
Supported decoding: simple, complex, rle, ieee, png, jpeg2000
Supported encoding: simple, complex, ieee, jpeg2000
default WMO names: NCEP
C compiler: gcc
CPPFLAGS= -Wall -Wmissing-prototypes -Wold-style-definition -Werror=format-security -ffast-math -O3 -DGFORTRAN
OpenMP: control number of threads with environment variable OMP_NUM_THREADS
INT_MAX: 2147483647
ULONG_MAX: 18446744073709551615
If you wish to access wgrib2 directly from the terminal anywhere as we do for other commands like ls , cp, df etc., copy the wgrib2 binary into the appropriate location as indicated below:
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cp -rfv wgrib2/wgrib2 /usr/local/bin/wgrib2
If you wish to clean up the compilation directory, simply delete the working directory we have used so far with the following command:
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rm -rfv ~/Downloads/wgrib2
That’s it for Linux users.
Install wgrib2 on Windows
For Windows, there is a precompiled version is available at https://www.ftp.cpc.ncep.noaa.gov/wd51we/wgrib2/Windows10/. Click on the directory that contains the latest version of wgrib2 and download all *.exe and *.dll files. Save all the downloaded files and run wgrib2.exe. That’s it.
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