FLEXPART v11 Global Trajectory Dataset (1979–2024)

Repository: link via Globus (https://app.globus.org/file-manager?origin_id=269ce146-5835-4e3c-91d0-f37c9166c52a&origin_path=%2F)

1. Dataset Overview

This dataset contains a full global archive of Lagrangian air-parcel trajectories (1979–2024) simulated with FLEXPART v11 (Bakels et al., 2024) using ERA5 (Hersbach et al., 2020) meteorological input fields. It provides the complete set of 3-hourly particle outputs (partoutput files) from domain-filling FLEXPART simulations using 20 million parcels and 90 vertical levels, suitable for:
- atmospheric moisture and heat transport analysis
- source–sink attribution
- recycling diagnostics
- extreme-event reconstruction
- land–atmosphere and ocean–atmosphere coupling studies
- ...

All FLEXPART raw outputs are shared to allow users to perform their own analyses or to use the accompanying HAMSTER v2 (https://github.com/h-cel/HAMSTER-v2) software for computing E2P/E2Q/H2T diagnostics.

2. Data Access

The entire dataset is available via Globus (https://app.globus.org/file-manager?origin_id=269ce146-5835-4e3c-91d0-f37c9166c52a&origin_path=%2F).
Each year is simulated separately and spans from December of the previous year through 31 January of the subsequent year, capturing transitional meteorological conditions across annual boundaries. 

3. Directory Structure

The dataset contains the following top-level elements:

/1979/
/1980/
/1981/
   ...
/2024/

nr_parcels_v11.txt
atm_mass_v11.txt

/flexpart_settings/
/flexextract_settings/

3.1 Yearly FLEXPART output folders (/YYYY/)

Each folder contains 3-hourly NetCDF output files of the form: partoutput_yyyymmddhhmmss.nc

These files store the complete state of all ~20 million parcels at each time step.

Variables are stored per particle (id) and include:

Variable    Description                  Unit
time          Timestamp                   s
lon, lat      Parcel position             degrees
z               Height above ground  m
sh             Specific humidity         kg kg⁻¹
rho           Density                         kg m⁻³
T               Temperature                K
pv             Potential vorticity        pvu
hmix         Mixing layer height     m
tro            Tropopause height      m
to             Topography field         m above sea level

Coordinates follow:
longitude: −180° to 180°
latitude: −90° to 90°

Temporal resolution: every 3 hours (00, 03, 06, 09, 12, 15,18 and 21 UTC)

The size of one simulation year is approx. 1.95 TB.

3.2 Metadata files

Two text files summarise the number of parcels and the atmospheric mass used in each yearly simulation.

3.3 FLEXPART configuration folder (/flexpart_settings/)

Contains all model configuration files used to run FLEXPART, including:

COMMAND
RELEASES
OUTGRID
...

These files document the configuration exactly as used in the simulations.

3.4 Flex_extract configuration folder (/flexextract_settings/)

Contains the COMMAND file used with flex_extract v7.1.2 (Tipka et al., 2020) to retrieve ERA5 fields.

4. Simulation Setup Summary

Model: FLEXPART v11 (Bakels et al., 2024)
Mode: forward trajectories
Meteorology: ERA5 (ECMWF)
Spatial resolution: 0.5°
Temporal resolution: 3-hourly outputs
Particles: 20 million (domain filling mode)
Vertical levels: 48–137
Simulation period: 1979–2024

5. Notes on Post-Processing (HAMSTER v2)

Users do not need HAMSTER (Keune et al., 2022) to use the dataset, but the trajectories are optimised for post-processing with:

HAMSTER v2 — a bias-corrected, MPI-parallelised tool for computing

- Evaporation-to-Precipitation (E2P)
- Evaporation-to-Precipitable Water (E2Q)
- Sensible Heat-to-Temperature (H2T)

HAMSTER reads the FLEXPART partoutputs directly and produces gridded source–sink maps.
The software package is publicly available at https://github.com/h-cel/HAMSTER-v2.

6. Citations

Bakels, L., Tatsii, D., Tipka, A., Thompson, R., Dütsch, M., Blaschek, M., Seibert, P., Baier, K., Bucci, S., Cassiani, M., et al.: FLEXPART version  11: Improved accuracy, efficiency, and flexibility, Geoscientific Model Development, 17, 7595–7627, 2024.
Hersbach, H., Bell, B., Berrisford, P., Hirahara, S., Horányi, A., Muñoz-Sabater, J., Nicolas, J., Peubey, C., Radu, R., Schepers, D., et al.: The ERA5 global reanalysis, Quarterly journal of the royal meteorological society, 146, 1999–2049, 2020.
Keune, J., Schumacher, D. L., and Miralles, D. G.: A unified framework to estimate the origins of atmospheric moisture and heat using Lagrangian models, Geoscientific Model Development, 15, 1875–1898, 2022.
Tipka, A., Haimberger, L., and Seibert, P.: Flex_extract v7. 1.2–a software package to retrieve and prepare ECMWF data for use in FLEXPART, Geoscientific Model Development, 13, 5277–5310, 2020.

Contact: victoria.deman@ugent.be