Downwind Puff Splitting
(when puff size exceeds data grid)


   load control file


   load setup file

numpar = 1

   namelist particle release number

initd = 3

   namelist Gaussian-horizontal particle-vertical

Puffs ...

  • Improves the representativeness of modelled flow over a single puff
  • Results in an ever-increasing number of puffs
  • When NPUFF>0.5*MAXPAR, puff splitting is turned off
  • When NPUFF>MAXPAR, emissions (new puffs) are turned off
  • If this occurs, air concentrations may be under-predicted
  • Address by increasing the value of MAXPAR

Particles ...

  • 3D particles provide better representation of a complex atmosphere
  • The HYSPLIT default is the 3D particle mode
  • The relation between particle number and grid size must be considered
  • Requires user to define the particle number and not rely upon puff-splitting to smooth the distribution