Community GSIV3.7 Online Tutorial | Getting Started > Download and Build GSI System

BUILDING GSI FROM SCRATCH

Obtaining the source code & setting up the directory

This exercise is intended to give you practice building the GSI system. This version of GSI system includes a WRF I/O library. There are no need to build the WRF model for this version GSI building.

The community GSI resources, including source code, build system, utilities, and fix files, are available for download from the DTC community GSI users website: https://dtcenter.org/community-code/gridpoint-statistical-interpolation-gsi/download.

The code downloads will result in the following tar file:

comGSIv3.7_EnKFv1.3.tar.gz

GSI requires use of CRTM coefficients to analyze satellite radiance observations. Due to their large size, these are available as a separate tarfile available for download by selecting the link: CRTM 2.3.0 Big_Endian coefficients tarball

The tars file may be unpacked using the UNIX commands:

tar -zxvf comGSIv3.7_EnKFv1.3.tar.gz

 

This creates the top level GSI directory: comGSIv3.7_EnKFv1.3

Setting up the machine environment

Set the necessary paths for using your selected compiler, such as loading the appropriate modules or modifying your path variable.

Before configuring the GSI code to be built, at least one, and no more than two environment variables must be set.

• NETCDF: the path to the NETCDF libraries
• LAPACK_PATH: the path to the LAPACK math libraries

For more detail, see GSIv3.7 Users' Guide Chapter 2.

Configure and Compile the GSI code

This version GSI can ONLY be compiled with Cmake. 

First create a building directory (any name works) outside the GSI directory:

mkdir build

Then, get into this building directory

cd build

Now run cmake to configure makefile by typing:

cmake ${Path To GSI Home Directory}/comGSIv3.7_EnKFv1.3

Cmake will check your computer environment and generate the makefile. A successful cmake run should end with:

-- Configuring done 
-- Generating done 
-- Build files have been written to: (Path_of_this_directory)/build

The building directory includes many new file and directories generated from Cmake:

bin cmake_install.cmake include Makefile Testing 
CMakeCache.txt CTestTestfile.cmake lib regression_var.out util 
CMakeFiles DartConfiguration.tcl libsrc src 

Now, we can simply run make to compile the GSI and its untilities:

make

If the compilation is successful, the executable gsi.x, will be created in the ./bin directory. If the compilation is not successful, run make with make VERBOSE=1 to collect more information on errors.

After a successful compilation:

Once GSI compiled correctly, return to the online tutorial page to set up and run the case(s) of your choice.