This tutorial explains how to use the FLEXPART Lagrangian dispersion model within Metview
DRAFT
How to prepare FLEXPART input data?
How to run FLEXPART?
To run a FLEXPART simulation you need to use the FLEXPART Run icon.The simulation itself requires:
- input meteorological fields
These can be generated for FLEXPART using the FLEXPART Prepare icon or with an external application. - the FLEXPART executable
At ECMWF it is centrally installed and does not need to be specified for FLEXPART Run. For a custom-build executable or at other sites please follow the instructions in FLEXPART setup. - some FLEXPART resources
FLEXPART needs a set of files to carry out a simulation: IGBP_int1.dat, OH_7lev_agl.dat, surfdata.t, surfdepo.t. At ECMWF these are centrally installed and do not need to be specified for FLEXPART Run. At other sites please follow the instructions here. - setting the SPECIES to be released
The species we can use in a FLEXPART simulation must be defined by a set of ASCII files. See details about their usage here. - specifying the releases
- defining the run conditions
- the path to the output files
Metview runs FLEXPART in a temporary folder then converts the results and copies them into this folder. FLEXPART outputs can be large so take it into account when selecting this path.
How to specify the FLEXPART executable?
How to define the SPECIES?
The species (chemical elements) released during a simulation are specified as integer numbers in the Release Species parameter in FLEXPART Run. The integer ID of the individual species are taken from the name of the species definition files.These have to be located in the directory defined
- via the User Species Path parameter in FLEXPART Run
- or if it is left blank (this is the default value) Metview will use the MV_FLEXPART_SPECIES environment variable.
The species distributed with FLEXPART
Folder option/SPECIES in the FLEXPART distribution contains a default set of species definitions. Here each species is represented by a file called SPECIES_NNN , where NNN is the integer ID of the given species.The table below summarises what species are available:
...
SPECIES_001
...
SPECIES_002
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SPECIES_024
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SPECIES_009
...
SPECIES_019
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SPECIES_020
...
At ECMWF
The species are located in the directory specified by environment variable MV_FLEXPART_SPECIES. The contents of this directory is the same as that of folder option/SPECIES in the FLEXPART distribution.
At other sites
Instructions to setup the species path can be found here.
Using your own definitions
If you want create your own species definition you need make a copy of this directory and add your own species to it. Then set the path in User Species Path so that FLEXPART could pick up your definitions.
How to define the releases?
A release is defined with the FLEXPART Release icon. In our example the release is defined with iconshappens at a point between 1651 and 9000 m. The emitted mass is 100 kg.
The macro code,
| Code Block | ||
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rel_volcano = flexpart_release(
name : "REL 1",
starting_date : 0,
starting_time : 15,
ending_date : 2,
ending_time : 12,
area : [63.63,-19.6,63.63,-19.6],
top_level : 9000,
bottom_level : 1651,
particle_count : 10000,
masses : 100
) |
The location of the FLEXPART executable and that of some other files/directories have to be specified for Metview. These locations can be defined either through a set of Metview environment variables or via parameters in the FLEXPART Run icon (these latter take precedence). The table below summarises what actually is needed to set for Metview.
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The directory containing the following files:
- IGBP_int1.dat
- OH_7lev_agl.dat
- surfdata.t
- surfdepo.t
...
These files are distributed in the FLEXPART source inside folder option
...
A set of species are distributed in the FLEXPART source inside folder option/SPECIES
...
A case study
In this case study will run FLEXPART for an Icelandic volcano eruption happened in 2012.
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PreparationsFirst start Metview; at ECMWF, the command to use is |
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The icons you will work with are already prepared for you - please download the following file:
You should now (after a few seconds) see a |
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flexpart_tutorial folder. |
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Please open it up. The input dataThe input data is already prepared for you and is located in folder 'Data'. |
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You will find a FLEXPART Prepare |
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-old icon that was used to generate the data in folder 'Prepare'. The corresponding macro code can also be found there. You do not need to run the data preparation. However, if you wish to do so please note that it requires MARS access and you must set the Output Path parameter accordingly. |
Tutorials
| Children Display | ||||
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Run a forward simulation
The fwd_conc FLEXPART Run icon defines the forward simulation. It requires the release description that we define with the vol_release icon. The macro geas like this:
The macro code,
| Code Block | ||
|---|---|---|
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rel_volcano = flexpart_release(
name : "REL 1",
starting_date : 0,
starting_time : 15,
ending_date : 2,
ending_time : 12,
area : [63.63,-19.6,63.63,-19.6],
top_level : 9000,
bottom_level : 1651,
particle_count : 10000,
masses : 100
) |
| Code Block | ||
|---|---|---|
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#Run flexpart (asynchronous call!)
r = flexpart_run(
output_path : "result_fwd_conc",
input_path : "../data",
starting_date : 20120517,
starting_time : 12,
ending_date : 20120519,
ending_time : 12,
output_flux : "on",
output_trajectory : "on",
output_area : [40,-25,66,10],
output_grid : [0.5,0.5],
output_levels : [500,1000,2000,3000,4000,5000,7500,10000,15000],
release_species : 8,
receptors : "on",
receptor_names : ["rec1","rec2"],
receptor_latitudes : [60,56.9],
receptor_longitudes : [6.43,-3.5],
releases : rel_volcano
) |
Forward simultaions
Fields
Trajecories
receprotros
volume fill
fluxes
cross section
time-height diagram
total column
age class
backward simulation
residence time
fluxes
trajecory