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• 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 in 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 in for FLEXPART Run. At other sites please follow the instructions in FLEXPART setup here.
• setting the SPECIES to be released
  The species we can be used use in a FLEXPART simulation must be described defined by a set of definition 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

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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.

At ECMWF 

The species distributed with FLEXPART

Folder The SPECIES are located in the directory specified by MV_FLEXPART_SPECIES. The contents of this directory is the same as that of 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 by default:

At

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ECMWF 

The species are located in the directory specified by environment variable

Using your own

filenames defining the ind

can be specified for using these two parameters:

User Species Path

Specifies the location of the user defined species files. Both an absolute and relative path can be given here. If it is left blank (this is the default value) Metview will use the MV_FLEXPART_SPECIES environment variable to locate the species.  

Release Species

Specifies the list of the species released for the simulation. At all release locations the same species are emitted. The species are identified by the NNN number appearing in the the name of the SPECIES_NNN files. These files contain the physical and chemical properties of species.  

On ecgate in your metview version MV_FLEXPART_SPECIES is set to

/usr/local/apps/flexpart/902/options/SPECIES

(you could find out this path by running your metview version with the -help option; this prints out,  among other things, all the FLEXPART related env variables).

. 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

The contents of this directory was simply taken from the FLEXPART distribution. 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,

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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A case study

In this case study will run FLEXPART for an Icelandic volcano eruption happened in 2012.

Preparations

First start Metview; at ECMWF, the command to use is metview (see Metview at ECMWF for details of Metview versions). You should see the main Metview desktop popping up.

You will create some icons yourself, but some are supplied for you - please download the following file:

You should now (after a few seconds) see a flexta_tutorial folder. You will work in this folder so open it up.

The input data

The input data is already prepared for you and is located in folder Data. The FLEXPART Prepare icon and its Macro equivalent can be found in the Prepare folder.

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,

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
	)

#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

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