flexprep 0.2.2

A Python library for pre-processing FLEXPART inputs

flexprep

WARNING:

This project is in BETA and under active development. Interfaces and functionality are subject to change.

flexprep is a Python toolkit to retrieve and preprocess ECMWF IFS fields for the Lagrangian particle dispersion model FLEXPART.

It uses ECMWF’s earthkit-data library to load meteorological GRIB data into familiar xarray/numpy arrays for computation, preserves GRIB metadata, and can write the results back to GRIB2.

Compatibility

Target model: FLEXPART V10

Install the latest release from PyPI

# pip
pip install flexprep

# or poetry
poetry add flexprep

At a glance

1. Retrieve IFS forecasts

   • via MARS
   • via Polytope
   • from local GRIB files

2. Preprocess for FLEXPART V10

   • De-accumulates precipitation, radiation, and fluxes
   • Converts etadot → omega (Pa s⁻¹)

3. Write GRIB2

   • Preserves/overrides GRIB metadata as needed
   • Ensures all fields are written as GRIB2

Documentation

See the docs/ folder for detailed information:

• Inputs
• Data Sources
• Preprocessing
• GRIB I/O

Changelog

See CHANGELOG.md for version history.

Running Tests

To run the full test suite:

git clone https://gitlab.phaidra.org/flexpart/flexprep.git
cd flexprep
poetry install --with dev
poetry run pytest

Feedback

Found a bug or have feedback? Please open an issue.

Roadmap / TODO

• Publish a hosted documentation site (e.g., Read the Docs or GitHub Pages)
• Add Copernicus Data Store (CDS) as a data source
• Find suitable package name (flexprep?)

Testing the flexprep Package

This guide explains how to test the flexprep pipeline using example scripts included in the repository. Each example demonstrates a full workflow: loading, preprocessing, and writing FLEXPART-ready GRIB2 files.

1️. Install the package

Option A — From PyPI

pip install flexprep==0.1.3

2️. Get the example scripts

Clone the repository to access the example workflows.

git clone https://gitlab.phaidra.org/flexpart/flexprep.git
cd flexprep

3. Run an example pipeline

Each example runs the flexprep pipeline end-to-end.

Data source	Command	Notes
🧪 Bundled test data	python examples/run_pipeline_local.py tests/data/test_sources_raw_ifs.tar.gz	Works offline using a small bundled dataset
💾 Local GRIB files	python examples/run_pipeline_local.py /path/to/grib_dir	Use your own GRIB directory
☁️ ECMWF MARS archive	python examples/run_pipeline_mars.py --date 2025-09-29 --time 12 --step "1/to/2/by/1" --max-level 137	Requires ECMWF MARS credentials (.ecmwfapirc)

3️. Check the outputs

After running a pipeline, the processed GRIB2 files are written to ./out_grib2/.

Each file corresponds to one forecast step (e.g. dispf2025072912).

Found a bug or have feedback? Please open an issue or contact [e-mail]