FLEXTRA trajectory model

Sample of FLEXTRA trajectories plotted.

What is FLEXTRA?

FLEXTRA is a programme to calculate mean-wind trajectories. FLEXPART was built on the code base of FLEXTRA, and both use the same input data format. Because FLEXTRA operates directly on the ECMWF eta levels, FLEXTRA trajectories will be more accurate than those in FLEXPART. However, it does not include turbulence or loss processes. It produces coordinates of the air parcel path along with some meteorological information for each trajectory point.

FLEXTRA is written in Fortran77. It requires GRIB libraries for reading in the ECMWF fields like FLEXPART.

FLEXTRA references

These papers are the scientific reference for the FLEXTRA model. Users are asked to quote these in publications.

  • Stohl, A., G. Wotawa, P. Seibert, and H. Kromp-Kolb (1995): Interpolation errors in wind fields as a function of spatial and temporal resolution and their impact on different types of kinematic trajectories. J. Appl. Meteor. 34, p. 2149-2165. full text as PDF (free access)
  • Stohl, A., and P. Seibert (1998): Accuracy of trajectories as determined from the conservation of meteorological tracers. Q. J. Roy. Met. Soc. 124, p. 1465-1484. link to abstract (PDF only for subscribers)

These references in BibTeX


A list of FLEXTRA users is available. If you are using FLEXTRA and not listed, please add yourself (after becoming a registered user). Please also correct any outdated entry.

FLEXTRA can be used through ECMWF's Metview software, see (bottom of page)

FLEXTRA roadmap and downloads

See FtRoadmap. Sourcecode can be downloaded as compressed tar files.

Last modified 2 years ago Last modified on Jan 30, 2022, 7:57:34 PM
hosted by ZAMG