FSCBG: An aerial spray dispersion model for predicting the fate of released material behind aircraft

Abstract The development of the aerial spray dispersion model FSCBG (Forest Service, Cramer, Barry and Grim) by the USDA Forest Service and the U.S. Army is reviewed. FSCBG predicts the behavior of spray material released through nozzles into the wake of a spray aircraft (helicopter or fixed-wing), traveling through idealized atmospheric effects, penetrating a canopy and depositing on the ground. FSCBG contains simplified models for the complex flow structure behind aircraft and the mechanisms that affect the fate of aerially released material: downwind drift, evaporation, canopy penetration, and ground and canopy deposition. Model development efforts encompass the areas of spray behavior, aircraft wake effects, meteorological influences, canopy interaction, and deposition. These efforts are supplemented by model validation with field tests. The ability of the model to quantify off-target spray drift is particularly important.