Measurements of water vapor and CO2 fluxes produced by a prescribed prairie fire using a micrometeorological flux tower and tethered balloon sounding system

Fire is known to affect meteorological conditions and atmospheric composition by adding carbon dioxide and other compounds to the atmosphere. It is also known to affect convective environment by adding heat and water vapor to the atmosphere. Although progress has been made towards quantifying these impacts through theoretical and numerical modeling studies, very few in-situ measurements have been available, especially measurements in the immediate environment of the fire largely because of the dangers born of the fire environment. A few existing measurements of fire plumes are mostly from aircraft transects made at some height and distance away from the actual fire. Because of the rapid dispersion and mixing by the atmosphere, the aircraft measurements are hardly representative of the environment immediate surrounding the fire.

This paper presents, to our knowledge, the first in-situ measurements of sensible and latent heat fluxs, CO2 fluxes, and radiative fluxes made during a prescribed burn of a prairie field by a micrometeorological flux tower within the prairie field. Vertical profiles within the fire plume was also measured using a tethersonde sounding system operated immediately downwind of the field. The observations show that the fire plume significantly enhanced the sensible heat fluxed by more than 1000 Wm-2, latent heat fluxes by over 350 Wm-2 , and CO2 fluxes by nearly 170 Wm-2 . The observed increase in water vapor mixed ratio agrees well with the estimates based on theoretical analysis.