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How to use FLEXPART with Metview?
VAPOR has its own internal data model and NWP data has to be converted into the VAPOR format. There are a set of VAPOR command line tools that can convert NetCDF input data into this format but there is no such tool available for GRIB.
Metview's VAPOR Prepare icon helps to overcome this difficulty and allows converting GRIB data into the VAPOR format.
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FLEXTRA can compute both forward and background trajectories using various trajectory types such as: three-dimensional, model level, mixing layer, isobaric and isentropic trajectories. Trajectory computations can be carried out in the three different modes. These are as follows:
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Metview provides a high level interface to prepare input data for FLEXPART from ECMWF's MARS archive (via the FLEXPART Prepare icon),
perform a FLEXPART integration (via the FLEXPART Run icon)
and visualise the resulting output files. For the visualisation the gridded outputs in FLEXPART's custom binary format are converted to GRIB.
The interface was written for version 9.02 of FLEXPART.
http://transport.nilu.no/flexpart
This website contains a link to the latest available FLEXTRA documentation:
http://zardoz.nilu.no/~andreas/flextra/flextra3.html
Please note that FLEXTRA is not an ECMWF development. FLEXTRA is not distributed with Metview, but it has to be downloaded from the web site specified above and installed separately. It is installed at ECMWF though.
About the Metview interface
Metview provides a high level interface to prepare input data for FLEXTRA, run FLEXTRA and visualise the resulting output files. The interface was developed and tested with version 5.0 of FLEXTRA, which is using GRIB API to handle GRIB2 fields.
The input file generation and visualisation do not require the existence of a FLEXTRA executable. However, FLEXTRA itself can be only run if an executable is present. The path to the FLEXTRA executable can be specified for Metview at installation time by setting the --with-flextra switch for configure. However, this path can be overridden at Metview start-up via the MV_FLEXTRA_EXE environment variable.
FLEXTRA is controlled through a set of parameter files which are all generated automatically by Metview in the background. The only exception is file AVAILABLE which can optionally be provided by the users (see Part 3 for details).
Further details
There is a tutorial available on the use of VAPOR FLEXPART with Metview. It explains both the data preparation steps and the basics of the visualisation.
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