Figure \ref{897779} shows the effect of different ignition criteria on the associated number of fire spots, resulting fire area, fire ROS, and firebrand generation. The ignition criteria is configured with total thresholds and number of neighbors of 1 and 3, such that t indicates the total threshold and n the number of neighbors (i.e., t1n1, t3n1, t1n3). The black lines (dashed and solid) show the uncoupled and coupled simulations without fire spots, i.e., firebrands are generated and transported but do not ignite fire spots.
When fire spotting is enabled, a higher number of fire spots (panel A) occurs in the simulations with the lowest thresholds (t1n1, blue lines) and their the fire area increases faster (panel B), as expected. However, due to the rapid fire propagation in t1n1, the number of generating sources (i.e., points where fire ROS is above the specified threshold, panel C) is lower than t1n3 and t3n1 (green and yellow lines), which is also reflected in the number of firebrands generated (panel D).
When fire spots are not present, the fire ROS (panel C) increases almost linearly with time. In the absence of turbulence (uncoupled), the number of generated firebrands (panel D) also increases linearly with time, whereas when turbulence is present, the firebrand generation varies approximately with the number of  generating sources. This variation is approximate because the generation interval is longer than the model timestep (fs_firebrand_gen_dt = 5);  hence the local maxima of generating sources may not always coincide with a generation cycle.