Sensitivity of prescribed burn weather windows to atmospheric dispersion parameters over southeastern USA

Abstract

Prescribed burning is an essential tool for forest and rangeland management that requires specific weather conditions to enable the efficient and safe application of fire. Prescribed burning is often limited by the ability to find suitable burn-days that fit within the identified weather parameters that balance good smoke dispersion and erratic fire behaviour. We analysed the sensitivity of the occurrence of widely used weather windows in the southeastern USA to modest changes in how they are defined. This analysis identified the most limiting prescription components and assessed where small changes in the prescription window can yield the greatest gains in additional burn-days. In the growing season (April–September), adjustments to mixing height offered the greatest such opportunity: a 12.5% increase in the upper-limit yields ~25% more burn-days during this period. During the dormant season (November–January), a 12.5% change in the upper-limit of transport wind yields ~20% more burn-days. Performing this analysis on the ventilation index revealed that comparable increases in burn-days were available by changing its upper limits. These results help inform ongoing discussions on potential changes to regional prescribed burn weather parameters that might help meet smoke management and treatment objectives in the southeastern USA and more broadly.