This tutorial explains how to use the FLEXPART Lagrangian dispersion model within Metview
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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 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,
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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
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These files are distributed in the FLEXPART source inside folder option
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A set of species are distributed in the FLEXPART source inside folder option/SPECIES
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A case study
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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'. You will find a FLEXPART Prepare -old icon that was used to generate the data in folder 'Prepare'. The corresponding macro code can also be found there. |
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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. |
Running a forward simulation
Enter folder 'fwd'
We will run FLEXPART to simulate the release of SO2 from the Icelandic volcano Eyjafjallajökull.
The simulation is defined via the 'fwd_conc' FLEXPART Run and the 'rel_volcano' FLEXPART Release icons, respectively. Both these are encompassed in the 'fw_cond.mv' Macro. For simplicity will use this macro to show the simulation in detail.
First we define the release like this:
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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
) |
This says that the release will happen over a 45 h period between heights 1651 and 10000 m at the location of the volcano and we will release 100 kg worth of particles.
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Please note that
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The actual simulation is carried out by calling flexpart_run()
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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 : [0.25,0.25],
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
)
print(r) |
Here the actual release species is specified as an integer code (for details about using the species please see here).
Forward simultaions
Fields
Trajecories
receprotros
volume fill
fluxes
cross section
time-height diagram
total column
age class
backward simulation
residence time
fluxes
Tutorials
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