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If you haven't already obtained the grib_api package, get it from the grib-api web site.
We recommend downloading the latest version. Some of the instructions for options below may differ with the very latest versions.
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To unpack the software:
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mkdir -p ecmwf/src cd ecmwf/src tar zxf grib_api-1.914.180-Source.tar.gz |
or if your version of tar doesn't support the 'z' option, do:
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gunzip grib_api_1.914.180.tar.gz tar xf grib_api-1.914.180.tar |
Configuring grib_api for OpenIFS
Grib_api uses the CMake command for configuration and compilation. CMake is available for modern Linux systems but may have to be installed.
Alternately grib_api supports installation via a 'configure' script, though this option is deprecated. See GRIB API Installation for more details and instructions below.
CMake compilation must be done is a separate build directory to the source and the install directory.
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cd ecmwf
mkdir bld
mkdir grib-api
cd bld
export CC=cc
export FC=ftn
cmake ../grib_api-1.14.0-Source \
-DCMAKE_BUILD_TYPE=Bit \
-DCMAKE_INSTALL_PREFIX="../grib-api" \
-DENABLE_NETCDF=ON \
-DENABLE_JPG=OFF \
-DENABLE_PNG=OFF \
-DENABLE_PYTHON=ON \
-DENABLE_FORTRAN=ON \
-DENABLE_GRIB_THREADS=ON |
Explanation of lines:
| These lines set the choice of compiler. CMake is often able to determine the available compilers for itself. However, in cases where multiple compilers are available, or where compiler wrappers are used (as on HPC systems), it's preferable to set these explicitly by use of environment variables. |
CMAKE_BUILD_TYPE=Bit | "Bit" here means 'bit-reproducible'. It instructs CMake to use conservative compiler options that are known to ensure bit-reproducibility in separate runs of OpenIFS. |
CMAKE_INSTALL_PREFIX="../grib_api" | This specifies the location where the 'make install' command will place the grib-api installation. |
ENABLE_NETCDF=ON | Enabling netcdf ensures the grib_to_netcdf command can be used. |
ENABLE_JPG=OFFENABLE_PNG=OFF | As OpenIFS does not deal with any image based GRIB data these options can be disabled, unless you have other grib data containing images that you need to work with. |
ENABLE_PYTHON=ON | Some of the utilities that come with OpenIFS make use of the python interface to grib_api, e.g. the tools to create and manipulate the model data. For this option to work, ensure that a python installation is available. |
ENABLE_FORTRAN=ON | This enables the Fortran interface to grib_api and should always be on. |
ENABLE_GRIB_THREADS=ON | This ensures grib_api is compiled to be 'thread-safe'. Although OpenIFS does not currently use multiple threaded calls to grib-api, future versions may do so this option is recommended. |
Configuring grib_api with configure script
If you are familiar with compiling and installing software on linux systems, you will be used to the following steps. Grib_api uses the GNU configure tool to ease building and compilation. It is tested on different platforms and compilers and should not cause any problems. If however, you do have a problem installing grib_api, please email: openifs-support@ecmwf.int.
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