WRF-SFIRE ignition

Back to the WRF-SFIRE user guide.

The fire starts from ignition lines with the given omidirectional ignition spread fire_ignition_ros rate until the given ignition radius, fire_ignition_radius, is reached. A single ignition point is specified as a line with both ends the same. The ignition is specified in the file namelist.input. Once a node is ignited, the normal fire propagation algorithm takes over from that node. For this reason, it is best to choose ignition points (or endpoints of the ignition line) from fire model mesh nodes. Otherwise, if the ignition rate of spread is low, it may take a long time for the fire to reach mesh nodes, and nodes at different but small distances from the ignition line may ignite at times that are not intended.

Choosing ignition points on the mesh

You can pick your ignition point from the fire mesh nodes. Their coordinates are in the variables FXLONG and FXLAT in the wrfinput file, after you run real.exe or ideal.exe.

Alternatively, you can use the interactive Matlab utility clamp2mesh to find the nearest mesh point to your desired ignition location automatically:

1. run real.exe or ideal.exe to create your wrfinput files
2. start Matlab in the WRFV3/test/em_fire directory in order to set up the search paths properly
3. cd in Matlab to your run directory and run clamp2mesh

Works with

• Matlab 2012a (probably also earlier versions with native NetCDF support, starting from 2008)
• WRF-SFIRE June 15, 2013 or later