Fire replay and cycling

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Back to the WRF-SFIRE user guide.

To specify the fire arrival time directly instead of the spread model:

  • Replace the variable TIGN_G in WRF input file by the desired fire arrival time (in seconds since the simulation start)
  • Set fire_perimerer_time in the fire section of namelist.input

The specified fire arrival time will be used to replay the fire, which generates heat fluxes into the atmosphere as usual, until fire_perimerer_time. The spread model then takes over.

If WRF is restarted from wrfrst file (set restart=.true. in namelist.input) or from wrfout file (set cycling=.true. in namelist.input) where TIGN_G at the restart time has been changed, then the fuel fraction and fire are area at the restart time are recomputed from the given fire arrival time, but this instantaneous change of the fuel fraction does not generate heat fluxes.

This feature allows a gradual spin up of the atmosphere over the period from the restart to fire_perimerer_time, to develop circulation from the fire forcing. It can be used for an ignition from a given fire perimeter (by creating an artificial fire arrival time from the perimeter), and for data assimilation (by modifying the fire arrival time array in response to data).


  • Mandel, J., A. K. Kochanski, M. Vejmelka, and J. D. Beezley, Data assimilation of satellite fire detection in coupled atmosphere-fire simulations by WRF-SFIRE. Advances in Forest Fire Research, D. X. Viegas, ed., Coimbra University Press, 716–724, 2014. doi:10.14195/978-989-26-0884-6_80
  • Kondratenko, Volodymyr Y., Jonathan D. Beezley, Adam K. Kochanski, and Jan Mandel, Ignition from a Fire Perimeter in a WRF Wildland Fire Model, 12th Annual WRF User's Workshop, Boulder, CO, June 2011. pdf arXiv:1107.2675 presentation