Wildfire fluxes evaluation during strong pyro-convection activity in Portugal

Abstract

Forest fires involve burning biomass, releasing smoke into the atmosphere with consequences not only for ecosystems but also for human health [1]. The smoke emitted by forest fires consists of several air pollutants, however, exposure to carbon monoxide is the main cause of death associated with fires, since it binds to hemoglobin compromising the supply of oxygen and leading to hypoxia, which can lead to myocardial dysfunction [1, 2, 3]. This study aims to evaluate the flux of several pollutants during October 2017 wildfires in Central Portugal. The CAMS Global Fire Assimilation System (GFAS) utilises satellite observations of fire radiative power (FRP) to provide near-real-time information on the location, relative intensity, and estimated emissions from biomass burning and vegetation fires [4]. In this study, the following wildfire flux variables are analysed, such as carbon monoxide (CO), carbon dioxide (CO2), nitrogen oxides (NOx), nitrous oxide (N20), black carbon (BC), particulate matter d < 2.5 µm (PM2.5), total particulate matter (PM), sulphur dioxide (SO2). In addition, the maximum altitude of the plume and the average altitude of the maximum injection were also investigated. The daily analysis indicated a maximum of wildfire fluxes on 15th October, as well as the maximum altitude of the plume reaching the high troposphere (~9km). Furthermore, CO2 presented the highest emission amount. This result is in accordance with the bibliography since in higher intensity fires, emissions are mainly CO2 and water. This happens because the fuel, organic matter, is constituted mostly by carbon [1]. Statistical analysis indicated that there is a significant positive correlation between the maximum altitude of the plume and the wildfire fluxes of the variables. This study suggests that the intense pyro-convection activity was responsible for injecting a huge amount of smoke and other biomass burning particles into the higher troposphere.