Effect of Small-Scale Wildfires on the Air Parameters near the Burning Centers

Egor Loboda,Veronika Tarakanova,Pavel Martynov,Andrey Dutov,Mikhail Agafontsev,Denis Kasymov,Konstantin Orlov,Yuliya Loboda,Yevgeniy Gordeev,Vladimir Reyno,Kirill Savin

doi:10.3390/atmos12010075

Abstract

The results of seminatural experiments on the study of steppe and field wildfires characteristic of the steppe and forest-steppe zones of Western Siberia are presented. Using infrared (IR) thermography methods, the main thermal characteristics of the fire front are derived, the flame turbulence scale is estimated, and changes in the structure function of the air refractive index are analyzed in the vicinity of a fire. The effect of a model fire on the change of meteorological parameters (wind velocity components, relative air humidity, and temperature) is ascertained. Large-scale turbulence is observed in the front of a seminatural fire, which is absent in laboratory conditions. The predominance of large-scale turbulence in a flame results in turbulization of the atmosphere in the vicinity of a combustion center. Strong heat release in the combustion zone and flame turbulence increase the vertical component of the wind velocity and produce fluctuations in the air refractive index, which is an indicator of atmospheric turbulization. This creates prerequisites for the formation of a proper wind during large fires. Variations in the gas and aerosol compositions of the atmosphere are measured in the vicinity of the experimental site.

Highlights

Many wildfires occur every year in the world
In [13,14], special attention is paid to the consequences of wildfires, which manifest themselves in a global change in biocenoses on one hand and in the impact of carbon, gas, and aerosol emissions on climate change on the other hand
A significant release of thermal energy during fires, accompanied by turbulent processes in the burning front, obviously affects meteorological parameters, namely wind speed, induced atmospheric turbulence, and changes in air temperature and relative humidity. Variations in these air parameters directly influence the transport of gaseous combustion products, smoke, and aerosols

Summary

Introduction

Many wildfires (forest, steppe, and peat) occur every year in the world. An increase in temperature can result in an increase in the size of the burnt-out area, fire frequency, and the scale of the effects [1,2]. A significant release of thermal energy during fires, accompanied by turbulent processes in the burning front, obviously affects meteorological parameters, namely wind speed, induced atmospheric turbulence, and changes in air temperature and relative humidity Variations in these air parameters directly influence the transport of gaseous combustion products, smoke, and aerosols. In [22], a hypothesis about “own wind” formed during large-scale forest fires was suggested on the basis of mathematical simulation and observations made during experiments with wildfires This phenomenon was considered the consequence of the release of a significant amount of thermal energy during combustion, convection, and the turbulence effect on the atmosphere in the burning front. The related experimental data expand the fundamental knowledge about the effect of wildfires on changes in wind speed, air temperature, turbulence, and transport of combustion products

Experiments

Findings

Start of the experiment