Machine issues & portability
On this page we provide links to compiler-specific information.
GNU Fortran compiler
The GNU Fortran compiler is our recommended open-source compiler for GEOS-Chem. Because gfortran is open-source, it can be used on a wide variety of platforms, including the [Amazon Web Services cloud computing platform]. GEOS-Chem is now compatible with gfortran 4.4.7 and higher. As of December 2018, the current version is gfortran 8.2.0.
We are currently experimenting with the use of Linux containers (such as Singularity) in order to provide a consistent computational environment (i.e. with the same libraries and compiler verisons) that can be used across multiple platforms. For more information, please see: this tutorial by Jiawei Zhuang.
A note on performance: When GEOS-Chem is compiled with the GNU Fortran compiler, it runs slower than when compiled with the proprietary Intel Fortran compiler, especially when running on Intel CPUs. This is because GNU Fortran, as an open-source software product, lacks the ability to take advantage of some proprietary Intel CPU optimizations. If performance matters to you, and your institution has an Intel site license, then you might want to consider using the Intel Fortran Compiler instead.
Intel Fortran Compiler
The Intel Fortran Compiler (aka ifort) can currently be used to compile GEOS-Chem. However, this compiler is proprietary and requires that you (or your IT department) to purchase a site license, which can be expensive.