Building

Download FLEXPART

There are two options to download FLEXPART:

  • Tarball

You can download a tarball with the latest release from the FLEXPART page and then extract the file:

tar -xvf <flexpart_vX.X.tar>
  • Git repository

If you have Git installed, you can clone the latest version from the Git repository:

git clone --single-branch --branch master https://gitlab.phaidra.org/flexpart/flexpart.git

Compiler

FLEXPART 11 is written in Fortran 2018. The following compilers can be used to compile FLEXPART:

  • GNU Fortran compiler version 8+ (gfortran)
  • Intel Fortran compiler (ifort)

For running FLEXPART in parallel mode, a compiler supporting OpenMP is required. In addition, libraries (in particular HDF5) should be compiled thread-safe.

Libraries

FLEXPART uses the following libraries:

These libraries are usually available as packages in most Linux distributions and macOS package managers. For example:

  • On Debian/Ubuntu: sudo apt install libeccodes-dev libnetcdff-dev
  • On macOS (Homebrew): brew install eccodes netcdf

Compiling FLEXPART

FLEXPART is compiled with make, which uses the Makefile in the src subdirectory. Starting from the root directory, you can compile FLEXPART with:

cd src/
make -j

since 2026, there is only one Makefile. If you want an overview of the allowed Makefile options, run: 

make help

This creates the executable FLEXPART_ETA. Note that this executable is intended for ECMWF data.

Parameters

Before compiling FLEXPART, you might want to change parameters defined in par_mod.f90:

  • dp, sp, dep_prec: Set the precision of the simulation.
  • lusekerneloutput: Switch for using a kernel for calculating concentrations/deposition. Default: True.
  • lparticlecountoutput: Switch to set output units to number of particles per grid cell. Default: False.
  • numpf: Number of precipitation fields read by the executable. This should correspond to the number of precipitation fields present in the meteorological data. Default: 1.
  • lpartoutputperfield: When using particle output (IPOUT=1), this switch sets whether all selected fields are written to one NetCDF file or to separate files (one per field).
  • Many additional parameters govern the different parameterization schemes within FLEXPART.

Compiling FLEXPART without eta coordinates

make -j eta=no

This creates the executable FLEXPART.

Compiling FLEXPART without NetCDF libraries

make -j eta=<yes/no> ncf=no

This creates the executable FLEXPART_BIN, or FLEXPART_ETA_BIN for eta=yes.

Paths

The provided Makefile uses predefined CPATH and LIBRARY_PATH values (defaults on many systems). If these paths are not available on your machine, edit the Makefile and set the correct paths manually or just during compilation with:

CPATH=/usr/include LIBRARY_PATH=/lib64 make

The default paths are also shown when running make help.

Optimisation

The default and recommended optimization flags in the Makefile are -O2 -march=native -mtune=native -fopenmp. If a parallelized version is not required, -fopenmp can be disabled using make serial=yes

Dependencies

At the bottom of the default Makefile, you can find the list of modules and how they depend on each other, in ascending order.