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This icon generates the gridded input data and the AVAILABLE file needed to run the FLEXTRA trajectory model. The input forecast or analysis fields are automatically retrieved from ECMWF's MARS archive. A tutorial on using FLEXTRA from within Metview is available from the Tutorials pageruns the FLEXPART Lagrangian particle dispersion model and converts its outputs to formats that Metview can work with. For help on editing icons, please see Editing Icons.

The macro language equivalent is flextraflexpart_preparerun().

About FLEXTRA input  data

The following is for information only - FLEXTRA Prepare handles these details internally.

FLEXTRA requires input fields on a regular latitude-longitude grid in GRIB format. The input data must contain four three-dimensional fields: the two horizontal wind components, vertical velocity and temperature. Two additional two-dimensional fields are needed as well: topography and surface pressure. The three-dimensional input data has to be available on ECMWF model (i.e. η) levels defined by a hybrid vertical coordinate system. An important restriction is that all the data fields used within a FLEXTRA run must have the same domain size, resolution, number of levels, etc.

All the required fields, with one exception, can be retrieved from ECMWF's MARS archive. The only exception is vertical velocity because FLEXTRA needs the following field for its computations:

Mathinline
\dot \eta \frac{\partial \eta}{\partial p}
Since only
Mathinline
\dot \eta
is archived in MARS the full product needs to be computed during the data preparation process (FLEXTRA Prepare does it for you).

FLEXTRA requires all the input GRIB files to be in the same folder using the following file naming convention: ENyymmddhh. In addition to the GRIBs FLEXTRA needs several parameter files as well. Most of these files are automatically generated by Metview in the background, so users do not need to create them. The only exception is the file called AVAILABLE because it can be optionally provided by the user.

The FLEXPART Run Editor

...


The FLEXPART Run Editor

Output Path

Specifies the location of the output data files. Both an absolute and relative path can be given here. Please note that Metview converts FLEXPART output into other formats and only these converted results are copied from the work directory into Output Path. For further details about the output formats click here.

Input Data

Specifies the location of the input data files and the AVAILABLE file using a FLEXPART Prepare icon. Please note that if an icon is set here it takes precedence over the path specified in Input Path.

Input Path

Specifies the location of the input data files and the AVAILABLE file. Both an absolute and relative path can be given here. Please note that when an icon is specified in Input Data this path is ignored.

User Exe Path

Specifies a user defined FLEXPART executable. Both absolute and relative path can be given here. If it is left blank (this is the default) Metview will use the MV_FLEXPART_EXE environment variable to locate the executable.

User Resources Path

Specifies the location of the user defined parameter files (IGBP_int1.dat, OH_7lev_agl.dat, surfdata.t, surfdepo.t ) needed to run FLEXPART. Both an absolute and relative path can be given here. If it is left blank (this is the default) Metview will use the MV_FLEXPART_RESOURCES environment variable to locate the resources. For further details about the resources click here.

Simulation Direction

Specifies the FLEXPART simulation direction in time. The possible values are: Forward and Backward. The default value is Forward.

Starting Date

Specifies the beginning date of the simulation in YYYYMMDD format.  Relative dates are allowed: e.g. -1 means yesterday, 0 means today, etc.

...

  

Starting Time

...

Specifies the

...

beginning time of the simulation in HH[:MM[:SS]] format. 

Ending

Input Path

The MARS experiment identifier of the forecast fields. The default value is 1 (operational forecast). 

Flextra An Mars Expver

The MARS experiment identifier of the analysis fields. The default value is 1 (operational analysis). 

...

Date

Specifies the

...

ending date of the

...

simulation in YYYYMMDD format.   Relative dates are allowed: e.g. -1 means yesterday, 0 means today, etc.   

Ending

...

Time

Specifies the run ending time of the forecast . Available when Flextra Prepare Mode is Forecast.

Flextra Step

Specifies the forecast steps in hours. Here a list of values is given. Available when Flextra Prepare Mode is Forecast.

Flextra Period Start Date

Specifies the start date of the period. Available when Flextra Prepare Mode is Period.

Flextra Period Start Time

Specifies the start time of the period. Available when Flextra Prepare Mode is Period.

Flextra Period End Date

Specifies the end date of the period. Available when Flextra Prepare Mode is Period.

Flextra Period End Time

Specifies the end time of the period. Available when Flextra Prepare Mode is Period.

Flextra Period Step

Specifies the time step of the period in hours. The allowed values are as follows: 3 or 6. Available when Flextra Prepare Mode is Period.

Flextra Area

simulation in HH[:MM[:SS]] format. 

Output Interval

Specifies the frequency for the output generation. The output is averaged over the period given in Output Averaging Interval. The format is HHHH[:MM[:SS]]. The default value is 3 (hours).

Output Averaging Interval

Specifies the averaging interval for the output generation in HHHH[:MM[:SS]] format.  If 0 is given here instantaneous values are written into the output files. The default value is 3 (hours).

Output Sampling Rate

Specifies the sampling rate used for the averaging of the output. This period must be shorter than the Output Averaging Interval. The format is HHHH[:MM[:SS]]. The default value is 0:15 (15 minutes).

Output Field Type

Specifies the type of the gridded output fields. The possible values are:

for forward simulations:

  • none (no gridded output)
  • conc (concentration)
  • mixr (mass mixing ratio)
  • both (concentration and mass mixing ratio)

for backward simulations:

  • none (no gridded output)
  • rtime (residence time/response function)

The default value is conc. For more details about gridded output click here.

Output Flux

Specifies if the fluxes should be computed and written out as a gridded output (on or off). Fluxes corresponding to northward, southward, eastward, westward, upward and downward directions are calculated for each grid cell of the output grid.The control surfaces are placed in the middle of each output grid cell. The default value is off. For more details about flux output click here.

Output Trajectory

Specifies if the plume trajectories should be computed (on or off). The default value is off.  For more details about trajectory output click here.

Output Area

Specifies the area for the gridded output in degrees in S/W/N/E format. The default value is  Specifies the area of the output grid in south/west/north/east format. The default value is  -90/-180/90/180.

...

Output Grid

Specifies the grid resolution of for the gridded output grid in dx/dy format, where dx is the grid increment in east-west direction, while dy is the grid increment in north-south direction (both in units of degrees)in degrees as east_west_resolution/north_south_resolution. The default value is : 1/1. 

Flextra Top Level

Only data on and below this model level will be used to generate the FLEXTRA input fields. This level can be specified either as a model level or as a pressure value. In the latter case FLEXTRA Prepare will use the data retrieved for the first date to determine the topmost model level. The default value of this parameter is 1, which means that all the model levels will be used if Flextra Top Level Units is set to Model Levels.

Flextra Top Level Units

Specifies the units of the value of Flextra Top Level. The allowed values are Model Levels or hPa. The default value is Model Levels. 

Flextra Reuse Input

If this parameter is set On FLEXTRA Prepare checks the existence of the data files to be generated and if they are already in place no new data is retrieved and processed. If it is Off all the fields are always retrieved and processed and the existing data files are overwritten. The same happens to the AVAILABLE file. The existence of a FLEXTRA input GRIB file is checked by using the file name and a set of GRIB API keys from the first message in the file. These keys are as follows: date, time, stepRange, gridType, iDirectionIncrement, jDirectionIncrement, latitudeOfFirstGridPoint, latitudeOfLastGridPoint, longitudeOfFirstGridPoint, longitudeOfLastGridPoint.

Flextra Output Path

Specifies the output directory (it has to be an absolute path) where the GRIB files and the AVAILABLE file will be generated. If this directory does not exist Metview will create it. The output GRIB files have the following naming convention: ENyymmddhh.

1. Simulation direction, 1 for forward, -1 for backward in time

 

2. Beginning date and time of simulation. Must be given in format

   YYYYMMDD HHMISS, where YYYY is YEAR, MM is MONTH, DD is DAY, HH is HOUR,

   MI is MINUTE and SS is SECOND. Current version utilizes UTC.

 

3. Ending date and time of simulation. Same format as 3.

 

4. Average concentrations are calculated every SSSSS seconds.

 

5. The average concentrations are time averages of SSSSS seconds

   duration. If SSSSS is 0, instantaneous concentrations are outputted.

 

6. The concentrations are sampled every SSSSS seconds to calculate the time

   average concentration. This period must be shorter than the averaging time.

 

7. Time constant for particle splitting. Particles are split into two

   after SSSSS seconds, 2xSSSSS seconds, 4xSSSSS seconds, and so on.

 

8. All processes are synchronized with this time interval (lsynctime).

Output Levels

Specifies the list of height levels of the gridded output. The levels are given in metres units. The default value is an empty list.

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. For more details about the species click here.

Release Species

Specifies the list of the species released for the simulation. At all the release locations the same species are emitted. The species are identified by the NNN number (with leading zeros) appearing in the the name of the SPECIES_NNN files. These files contain the physical and chemical properties of species. For more details about the species click here.

Release Units

Specifies the units of the mass of the released species. The possible options are mass and mixr. The default value is mass. See the table below to find out what the actual units mean.

for forward simulations:

Release UnitsReceptor Units
keywordunitskeywordunits in concentration fields
masskgmasskg m**-3
masskgmixrkg kg**-1
mixr1masskg m**-3
mixr1mixrkg kg**-1

for backward simulations:

Release UnitsReceptor Units
keywordunitskeywordunits in residence time fields
mass1masss
mass1mixrs m**3 kg**-1
mixr1masss kg m**-3
mixr1mixrs

Releases

Specifies the releases as a group of FLEXPART Release icons. 

Receptor units

Specifies the concentration units at the receptor. The possible options are mass (mass concentrations) and mixr (mass mixing ratio). The default value is mass. See the table above to find out what the actual units mean.

Receptors

Enables the usage of receptor sites (on or off). When it is enabled the list of receptor sites can be defined via Receptor Names, Receptor Latitudes and Receptor Longitudes. The default value is off. For more details about receptor output click here.

Receptor Names

Specifies the list of receptor site names.The default value is an empty list.

Receptor Latitudes

Specifies the list of receptor site latitudes. The default value is an empty list.

Receptor Longitudes

Specifies the list of receptor site longitudes. The default value is an empty list.

Age Classes

Specifies the list of times for the age class calculation. If it is left blank (this is the default value) no age class is defined.  

Particle Splitting

Specifies the interval for particle splitting in HHHH[:MM[:SS]] format. Each particle is split into two after travelling the multiple of this interval. If 0 (default value) is given here particle splitting is disabled.

Sync Interval

All processes are synchronized with this time interval, therefore   Therefore, all other time constants must be multiples of this value.    Output interval and time average of output Output Averaging Interval must be at least twice lsynctimeof this value. The default value is 900.

 

...

Ctl

Specifies the factor by which the time step must be smaller than the Lagrangian time scale (TL). CTL must be >1 for time steps shorter than

...

the Lagrangian time scale

...

. If CTL<0, a purely random walk simulation is done

...

 

...

. The default value -5.

Vertical Timestep Reduction

Specifies the reduction factor (as an integer) for the time step used for vertical wind

...

. The default value is 4.

Subgrid Terrain

Enables subgridscale terrain parametrization (increase of

 

11.IOUT determines how the output shall be made: concentration

   (ng/m3, Bq/m3), mixing ratio (pptv), or both, or plume trajectory mode,

   or concentration + plume trajectory mode.

   In plume trajectory mode, output is in the form of average trajectories.

 

12.IPOUT determines whether particle positions are outputted (in addition

   to the gridded concentrations or mixing ratios) or not.

   0=no output, 1 output every output interval, 2 only at end of the

   simulation

 

13.Switch on/off subgridscale terrain parameterization (increase of

   mixing heights due to subgridscale orographic variations)

 

14.Switch on/off the convection parameterization

 

15.Switch on/off the calculation of age spectra: if yes, the file AGECLASSES

   must be available

 

16. If IPIN=1, a file "partposit_end" from a previous run must be available in

    the output directory. Particle positions are read in and previous simulation

    is continued. If IPIN=0, no particles from a previous run are used

 

17. IF IOUTPUTFOREACHRELEASE is set to 1, one output field for each location

    in the RLEASE file is created. For backward calculation this should be

    set to 1. For forward calculation both possibilities are applicable.

 

18. If IFLUX is set to 1, fluxes of each species through each of the output

    boxes are calculated. Six fluxes, corresponding to northward, southward,

    eastward, westward, upward and downward are calculated for each grid cell of

    the output grid. The control surfaces are placed in the middle of each

    output grid cell. If IFLUX is set to 0, no fluxes are determined.

 

19. If MDOMAINFILL is set to 1, the first box specified in file RELEASES is used

    as the domain where domain-filling trajectory calculations are to be done.

    Particles are initialized uniformly distributed (according to the air mass

    distribution) in that domain at the beginning of the simulation, and are

    created at the boundaries throughout the simulation period.

 

20. IND_SOURCE switches between different units for concentrations at the source

    NOTE that in backward simulations the release of computational particles

    takes place at the "receptor" and the sampling of particles at the "source".

          1=mass units (for bwd-runs = concentration)

          2=mass mixing ratio units

21. IND_RECEPTOR switches between different units for concentrations at the receptor

          1=mass units (concentrations)

          2=mass mixing ratio units

 

22. MQUASILAG indicates whether particles shall be numbered consecutively (1) or

    with their release location number (0). The first option allows tracking of

    individual particles using the partposit output files

 

23. NESTED_OUTPUT decides whether model output shall be made also for a nested

    output field (normally with higher resolution)

 

24. LINIT_COND determines whether, for backward runs only, the sensitivity to initial

    conditions shall be calculated and written to output files

    0=no output, 1 or 2 determines in which units the initial conditions are provided.

 

) (on or off). The default value is off.

Convection

Enables convection parametrization (on or off). The default value is off.

Output For Each Release

Specifies whether a separate output fields should be generated for each release (on or off). When this option is set to off for forward simulations the output fields for a given species contain the sum of all the releases. For backward simulations it must be set to on. The default value is off.

Quasi Lagrangian

Specifies whether particles should be numbered individually (on) or identified by the release location number (off). The default value is off.

Domain Fill

Enables the domain fill mode. The possible values are as follows:

  • no: domain fill is disabled
  • full: in this mode the the particles are not released at specific locations but the 3D-volume of the first release is taken and the particles are uniformly distributed in the volume proportionally to air density. Each particle will receive the same mass, altogether accounting for the total atmospheric mass. Subsequently, particles can move freely in the atmosphere.
  • o3_tracer: in this mode domain-filling is to simulate a stratospheric ozone tracer. This option is similar to fill option, but only particles in the stratosphere (defined by PV < 2 pvu) are released.

The default value is no.

Sensitivity

Enables computing sensitivity to initial conditions in backward simulations. The possible values are no, mass (mass concentration units) or mixr (mass mixing ratio units). The default value is none.