Trajectory model FLEXTRA
Particle Diffusion model FLEXPART
Disclaimer: This software is part of the FLEXTRA and FLEXPART program package. The same regulations as accepted by using FLEXTRA and FLEXPART do apply. These programs are public domain software.
Literature: G. Wotawa, A. Stohl: A tracer dispersion model driven by global-scale analyses and mesoscale (MM5) model output and its validation with tracer experiment data. Proceedings of the 11th Joint Conference on the Applications of Air Pollution Meteorology together with the A&WMA. American Meteorological Society, Boston, 446 p (2000).
This version is outdated. Please use
This document describes in short how to obtain and use the MM5 versions of the trajectory model FLEXTRA and the particle diffusion model FLEXPART. FLEXTRA is a user-friendly, flexible trajectory model capable of calculating different types of air trajectories (3-D, isobaric, model level following, isentropic). It can calculate trajectories for different starting points, but also for selectable grids. FLEXPART is a Lagrangian particle diffusion model. Due to its advection scheme, FLEXPART is free from any type of numerical diffusion, making it to one of the most accurate diagnostic tool for transport on all scales available. MM5 is a state-of-the-art non-hydrostatic nested grid numerical weather prediction model.
FLEXPART is usually fed with data from the global weather prediction model operated by the European Center for Medium-Range Weather Forecasts (ECMWF). The MM5 version makes FLEXPART capable to diagnose transport on scales from global down to plumes from cities and large power plants.
Information about FLEXTRA in general can be obtained from the .
Information about FLEXPART in general can be obtained from the .
Information about MM5 in general can be obtained from the .
This documentation consists of two parts:
Preparing MM5 output data as FLEXTRA/FLEXPART input (preprocessor program)
Applying the MM5 versions of FLEXTRA and FLEXPART
Nonhydrostatic MM5 output (hydrostatic output is not supported)
MM5 V2 output (V3 not supported yet)
Notice: There are utility programs offered at the MM5 home page which transform V3 output to V2 output
Lambert Conformal projection
Maximum temporal resolution of output 1 minute (otherwise problems with file naming convention)
These programs have the purpose to
Read the MM5 V2 output (nest 1-k)
Write the part of the output, which is needed by FLEXTRA/FLEXPART, into one file per nest level and time, as required by FLEXTRA/FLEXPART
Reduce disk space requirements by transforming data into ECMWF grib code
Create the information files AVAILABLE and GRID.TXT needed by FLEXPART. GRID.TXT informs FLEXPART about the grid specifications of your MM5 run, AVAILABLE about the input data availability of your simulation (in terms of windfields)
After running the preprocessing routine, original (V2) MM5 output is no longer needed and can be removed from disk.
You will need, as for FLEXTRA/FLEXPART, the ECMWF grib library. See the FLEXTRA/FLEXPART homepages for details.
The routines need as input the files and . While it is not recommended to modify PARAMETER, the file CONTROL has to be modified to include the correct pathnames and specifications.
If you have more than 1 MM5 run, then you can set number of strarts/restarts (line 2) to the number of different runs you have, or you can execute the program twice or three times in line with the different paths to the MM5 output files. In any case, the AVAILABLE files needed by FLEXPART in any nest level are updated automatically. Please note that, if you have overlapping MM5 output files (e.g., one file ends at 19980702 00:00, while the next starts at 19980701 12:00), the overlapping period will be written twice to your AVAILABLE file, forcing FLEXTRA/FLEXPART to an error. You can either correct this manually, what I would not recommend, or you can tell the program "skip the first 13 timesteps" (last line).
Download these routines here.
The FLEXTRA Version currently available for MM5 is FLEXTRA 3.0. There are no differences is input/output between FLEXTRA3.0 for ECMWF and FLEXTRA 3.0 for MM5. There is a documentation available. To get the FLEXTRA for MM5 source code, click here.
The FLEXPART Version currently available for MM5 is FLEXPART 3.1. There are some differences in input and output between FLEXPART 3.1 for ECMWF and FLEXPART 3.1 for MM5, which are briefly described later on. To get the FLEXPART 3.1 docu, click here. To get the FLEXPART for MM5 source code, click here.
Differences in Input:
File RELEASES: Specification of release locations. Instead of specifying the RELEASE locations with lower left and upper right co-ordinates, they are specified with the geographical coordinate of the release center plus a release grid distance dx and dy (for a point release, dx and dy can be set zero). The RELEASE box is specified in the lambert conformal projection instead of a latitude-longitude domain.
File OUTGRID: The FLEXPART output grid has to be specified in the Lambert conformal projection co-ordinate system instead of a latitude-longitude domain.
Differences in Output:
The FLEXPART output grid is in the Lambert conformal projection co-ordinate system instead of the geographical latitude-longitude system. As additional information, projection center co-ordinates, cone factor and true latitude are written out (see routines openoutput.f and openoutputppt.f).
Questions/comments: Please contact me.