Smoke plume height measurement of prescribed burns in the south-eastern United States

Abstract

Smoke plume height is important for modelling smoke transport and resulting effects on air quality. This study presents analyses of ceilometer measurements of smoke plume heights for twenty prescribed burns in the south-eastern United States. Measurements were conducted from mid-winter to early summer between 2009 and 2011. Approximately half of the burns were on tracts of land over 400 ha (1000 acres) in area. Average smoke plume height was ~1 km. Plume height trended upward from winter to summer. These results could be used as an empirical guideline for fire managers to estimate smoke plume height in the south-eastern US when modelling and measurement are not available. The average could be used as a first-order approximation, and a second-order approximation could be obtained by using the average for spring and autumn seasons, and decreasing or increasing by 0.2 km the average for winter or summer. The concentrations of particulate matter with an aerodynamic diameter less than 2.5 or 10 μm (PM2.5 and PM10) within smoke plumes calculated from ceilometer backscatter are ~80 and 90 μg m–3, and trend downward from winter to summer. Large smoke concentrations are found in the lower portion of smoke plumes for many burns. Smoke plume height shows fast and uniform fluctuations at minute scales for almost all burns and slow and irregular fluctuations at scales from tens of minutes to hours for some burns.