FLEXPART output

Outputs

Metview runs FLEXPART in a temporary directory. Having finished the simulation Metview converts and rename the output files and move them into the output_path directory specified in flexpart_run(). The different output types are handled in a different way.

Gridded outputs

Gridded outputs are converted to GRIB using local GRIB definitions built into Metview.

FLEXPART GRIB files have their own local section (Section 2) containing additional information about the given field and the FLEXPART simulation itself. The snapshot below taken from Metview’s Grib Examiner shows the currently defined set of keys in Section 2.

Handling FLEXPART GRIB output

To plot a particular parameter and level we need to filter the desired fields from the resulting FLEXPART output GRIB file. Unfortunately, Metview’s Grib Filter icon cannot handle these files (partly due to the local GRIB definition they use) so we need to use Macro with some FLEXPART-related command to deal with this problems. See the FLEXPART tutorial for details.

Concentration fields

Concentration fields are only produced for forward simulations when output_field_type is set to conc or both in flexpart_run().

The output filename is:

conc_sSSS.grib

where SSS is the species index (starts from 1) with leading zeros. The actual field type and units are based on the receptor_units settings in flexpart_run().

Options in FLEXPART Run	Description	GRIB shortName	GRIB paramId	GRIB units
receptor_units=mass	mass concentration	conc	20000	kg m**-3
receptor_units=mixr	mass mixing ratio	mxrm	20002	kg kg**-1

Volume mixing ratio fields

Volume mixing ratio fields are only produced for forward simulations when output_field_type is set to mixr or both in flexpart_run().

The output filename is:

pptv_sSSS.grib

where SSS is the species index (starts from 1) with leading zeros.

Description	GRIB shortName	GRIB paramId	GRIB units
volume mixing ratio	mxrv	20052	mol mol**-1

Dry and wet deposition fields

These fields are only produced for forward simulations when output_dield_type is set to conc, mixr or both in flexpart_run(). They are always inserted into the concentration or/and volume mixing ratio files.

Description	GRIB shortName	GRIB paramId	GRIB units
dry deposition	fdd	20197	kg m**-2
wet deposition	fwd	20198	kg m**-2

Flux fields

These fields are only produced when output_flux is set to on in flexpart_run(). The output filename is:

flux_sSSS.grib

where SSS is the species index (starts from 1) with leading zeros.

Description	GRIB shortName	GRIB paramId	GRIB units
eastward flux	feflux	20199	kg m**-2 s**-1
westward flux	fwflux	20200	kg m**-2 s**-1
southward flux	fnflux	20201	kg m**-2 s**-1
northward flux	fsflux	20202	kg m**-2 s**-1
upward flux	fuflux	20203	kg m**-2 s**-1
downward flux	fdflux	20204	kg m**-2 s**-1

Residence time/response fields

These fields are only produced for backward simulations when output_field_type is set to rtime in flexpart_run(). The output filename is:

time_sSSS.grib

where SSS is the species index (starts from one) with leading zeros.

Plume trajectories

Trajectories are produced when output_trajecory is set to on in flexpart_run(). The ASCII file generated by FLEXPART is split according to releases and converted into another (CSV) format that is better suited to metview. The output filenames are:

tr_rRRR.csv

where R is the release number (starts from one) with leading zeros. The first row in the trajectory file contains metadata as a set of key value pairs, while the the second row contains the header. The table below gives a detailed description about the different columns.

Co lumn	Name (header)	U nits	Description
1	time	s	the elapsed time in seconds since the middle point of the release interval
2	meanLon	deg rees	mean longitude position for all the particles
3	meanLat	deg rees	mean latitude position for all the particles
4	meanZ	m	mean height for all the particles (above sea level)
5	meanTopo	m	mean topography underlying all the particles
6	meanPBL	m	mean PBL (Planetary  Boundary Layer) height for all the particles (above ground level)
7	meanTropo	m	mean tropopause height at the positions of particles (above sea level)
8	meanPv	PVU	mean potential vorticity for all the particles
9	rmsHBefore	km	total horizontal RMS (root mean square) distance before clustering
10	rmsHAfter	km	total horizontal RMS distance after clustering
11	rmsVBefore	m	total vertical RMS distance before clustering
12	rmsVAfter	m	total vertical RMS distance after clustering
13	pblFract	%	fraction of particles in the PBL
14	pv2Fract	%	fraction of particles with PV<2pvu
15	tropoFract	%	fraction of particles within the
16*	clLon_N	deg rees	mean longitude position for all the particles in cluster N
17*	clLat_N	deg rees	mean latitude position for all the particles in cluster N
18*	clZ_N	m	mean height for all the particles in cluster N (above sea level)
19*	clFract_N	%	fraction of particles in cluster N (above sea level)
20*	clRms_N	km	total horizontal RMS distance in cluster N

Columns 16-20 get repeated for each cluster.

Receptor output

Output at receptor points are produced when receptor is set to on in flexpart_run(). The binary file generated by FLEXPART is split according to species and converted to CSV.

When receptor_units is set to mass in flexpart_run() the output filename is:

receptor_conc_sSSS.csv

When receptor_units is set to mixr in flexpart_run:ref:() the output filename is:

receptor_pptv_sSSS.csv

where SSS is the species number (with leading zeros).