Opened 2 years ago

Closed 2 years ago

#184 closed Support (fixed)

Particle Positions from Flexpart-Wrf Output

Reported by: mhakimzadeh Owned by: pesei
Priority: minor Milestone:
Component: FP other Version: FLEXPART-WRF
Keywords: Cc:


I need to get particle positions after I release the particles in my measurement site in order to have the number of trajectory segment endpoints in cell ijth in T time interval. I need particle positions in order to obtain Residence Time Analysis and subsequently, Concentration Field Analysis.
My question is how can I get the particle positions? Is CONC output parameter (in netCDF format) with s. m3 /kg unit representing the residence time of each grid divided by concentration at the measurement site? If not, what is this parameter representing?
Many Thanks in advance for your kind help.

Change History (7)

comment:1 Changed 2 years ago by pesei

FLEXPART calculates concentration itself. You don't need to residence times or trajectory output for that.

As a further background to your questions, you can study the Seibert and Frank (2004) paper (see

comment:2 Changed 2 years ago by pesei

  • Owner set to pesei
  • Status changed from new to accepted

comment:3 Changed 2 years ago by pesei

Are you satisified with the answer? Can I close the ticket? If I don't hear from you, I'll assume yes.

comment:4 Changed 2 years ago by mhakimzadeh

Many thanks for your help.
As I have understood, the "CONC" output of flexpart-wrf for each grid in each time interval gives us the value of concentration (which should be in unit of kg/ (m3.s) ) at release point if there is an emission equal to 1 kg/s in that grid.
However, my problem is that why the "CONC" values of output are in units of m3.s/kg?


Last edited 2 years ago by mhakimzadeh (previous) (diff)

comment:5 Changed 2 years ago by mhakimzadeh

Dear all,

I still have this question and my problem is still unsolved. Would you please help me with this question?


comment:6 Changed 2 years ago by adingwell

The m3*s/kg unit corresponds to a backward run (see e.g. ) with ind_source = 1 and ind_receptor = 2.

For a forward run, the CONC variable will contain the concentration field and a have a unit of ng/m3.

The CONC variable name also is used for the source-receptor relationship in backward runs. This was a quick solution for getting backward support into flexpart-wrf's netcdf output. (The backward format for netcdf-output has -- as far as I know -- has not been tested thoroughly...)

As for particle positions, if you really need it, I think the easiest way is to read it from the particle_dump (you generate these by setting IPOUT to 1 or 2). Note however, that these will not be on netCDF format(!)

comment:7 Changed 2 years ago by pesei

  • Resolution set to fixed
  • Status changed from accepted to closed
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