How to run the standalone fire model in WRF-SFIRE

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The fire code in WRF-Fire, called SFIRE (for Spread FIRE model), can be used independently without WRF, using only one-way atmosphere-fire coupling. WRF needs to run first to create the atmospheric forcing first.

Step by step instructions

  • cd wrf-fire/standalone
  • Find a suitable make.inc.* file and soft-link it to make.inc, for example ln -s make.inc.gfortran make.inc
  • Navigate to a directory with your example (such as WRFV3/test/em_fire/hill). Make sure namelist.input specifies a short history_interval_s (these will be the atmosphere states used by the fire model) and set large frames_per_outfile so that only one wrfout file is created.
  • Run wrf.exe as usual.
  • Link or rename the created wrfout file to fire_input.nc
  • Run fire.exe in the same directory. This will create the file fire_output.nc with the results.

How it works

  • The standalone model fire.exe reads the fire model inputs from the wrfout, including interpolated wind fields UF and VF. Because the first frame in wrfout is called before the fire model is called and so those fields are not set yet, the fire model starts from the second frame. The atmosphere fields are interpolated linearly in time between the frames before they are passed to the fire model.
  • The file fire_output.nc has the same format as wrfout but it contains only the variables that are the fire model outputs and some other fields copied from wrfout, which are needed for visualization and interpreting the results. These include coordinates of the fire nodes in FXLONG and FXLAT, the time string Times, and the terrain height ZSF.

Remarks

  • The results of the coupled model and the standalone model will not be identical, even if the coupled model runs the same fire, because the wind fields are interpolated between the frames for the standalone model. But the results should be close.
  • To simulate different fires in the standalone model, the coupled model should run without ignition. Then the coupled model will create the fire model inputs, but the atmosphere state will not be disturbed by the fire in the coupled model.
  • The &fire section in namelist.input can change, and the fuel data including namelist.fire may also change.
  • At the moment, fire.exe is serial only.

Works with

See also

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