Atmospheric dynamics and fire-induced phenomena: Insights from a comprehensive analysis of the Sertã wildfire event
Isilda Menezes, Diogo Lopes, Ana Patrícia Fernandes, C. Borrego, D. X. Viegas, Ana Isabel Miranda
Abstract
The Sertã wildfire started on October 15th, 2017, in a mountainous area in central Portugal, on the hottest day of an exceptionally dry month compared to the previous two decades. This dry spell was attributed to a persistent heatwave from October 1st to 16th, which impacted most of mainland Portugal. Due to the critical weather and vegetation conditions, the fire was very intense, generating a thermal plume that reached high altitudes. The main purpose of this work is to analyze and discuss the impact of the Sertã wildfire on the dynamics of atmospheric mountain circulation. To accomplish this, a numerical modeling system integrating meteorological, fire spread, and smoke dispersion models was employed. The results indicate that the interaction between the wildfire and the local mountain breeze in central Portugal, under the synoptic weather conditions in Europe, which included the Hurricane Ophelia over the Atlantic Ocean and a warm-sector polar frontal depression in northern Europe, led to a locally disturbed weather situation. The consistent, efficient, and uniform local transport of atmospheric properties at lower levels was disrupted, intensifying wind shear and developing more turbulent advection patterns. Moreover, the fire's impact contributed to the development of a baroclinic wave at 500 hPa over mass centers, which settled at the surface and enhanced cloud development over the region. This phenomenon aligns with the atmospheric circulation effects studied in the Bjerknes and Rossby theories. • Analysis of the 2017 Sertã Forest Fire Complex in central-northern Portugal. • This fire ignites amid extreme dryness, influenced by Hurricane Ophelia. • Impact that fire behavior had on the dynamics and thermodynamics of the atmosphere. • Dispersion and interaction of smoke with turbulence induced by heat plumes. • Analysis of particulate matter dispersion in the atmosphere.