Flex_extract is an open-source software to retrieve meteorological fields from the European Centre for Medium-Range Weather Forecasts (ECMWF) MARS archive to serve as input files for the FLEXTRA/FLEXPART atmospheric transport modelling system. Flex_extract was created explicitly for FLEXPART users who want to use meteorological data from ECMWF to drive the FLEXPART model. The software retrieves the minimum set of parameters needed by FLEXPART to work, and provides the data in the specific format required by FLEXPART.

Flex_extract consists of two main parts:
  1. a Python part which reads the parameter settings, retrieves the data from MARS, and prepares them for FLEXPART, and

  2. a Fortran part which calculates the vertical velocity and, if necessary, converts variables from the spectral representation to regular latitude/longitude grids.

In addition, there are some Korn shell scripts to set the environment and batch job features on ECMWF servers for the gateway and remote mode. See Application modes for information of application modes.

A number of Shell scripts are wrapped around the software package for easy installation and fast job submission.

The software depends on some third-party libraries as listed in Dependencies.

Details of the tasks and program work steps are described in Program flow.