Rothermel-Coupling

Midflame-height wind component — converts horizontal 10m wind components (u_wind, v_wind) to Rothermel's midflame-height wind speed U and wind direction omega relative to the upslope direction. Migrated from WildlandFire.jl@126976f2 src/coupling.jl:249 (`MidflameWind` @component). Observed-only: u_wind, v_wind, slope_aspect, wind_reduction are inputs (parameters); U, omega, u_mf_x, u_mf_y are algebraic outputs. The wind reduction factor (default 0.4 for timber fuels) converts 10m wind speed to midflame height (~6.1 m).

Terrain slope magnitude and aspect from elevation gradients. Migrated from WildlandFire.jl@126976f2 src/coupling.jl:205 (`TerrainSlope` @component). Observed-only: dzdx and dzdy are inputs (parameters); tan_phi, slope_aspect, dzdx_out, dzdy_out are algebraic outputs.