Implementation of the Firebrand Spotting Parameterization

The Firebrand Spotting parameterization was developed for WRF-Fire in WRF-ARW versions starting at V4.4, with fire spot ignitions implemented in the upcoming V4.6.x. This subsection describes the most recent parameterization implementation. The source code is written in FORTRAN 2003 following the WRF model coding standards. It consists of two distinct modules, one containing the main firebrand spotting code and associated routines, and another, for specific Message Passing Interface (MPI) routines that were not part of the WRF model. Both modules are included within the WRF physics source code. The firebrand processes modeled by the parameterization are firebrand generation, transport, physics, and landing. In this Lagrangian framework, firebrands are modeled individually and may ignite fire spots at landing when ignition conditions are met. The main aspects of the parameterization are illustrated in Figure 1 and described in detail in the following subsections.