Smoke Emissions and Buoyant Plumes above Prescribed Burns in the Pinelands National Reserve, New Jersey

Published

September 21, 2024

Author(s)

Kenneth Clark, Michael Gallagher, Nicholas Skowronski, Warren Heilman, Joseph Charney, Matthew M. Patterson, Jason Cole, Eric Mueller, Rory Hadden

Abstract

Prescribed burning is a cost-effective method for reducing hazardous fuels in pine and oak-dominated forests, but smoke emissions contribute to atmospheric pollutant loads and the potential exists for exceeding Federal air quality standards designed to protect human health. Fire behavior during prescribed burns influences above-canopy sensible heat flux and turbulent kinetic energy (TKE) in buoyant plumes, affecting the lofting and dispersion of smoke. A more comprehensive understanding of how enhanced energy fluxes and turbulence are related during the pas-sage of flame fronts could improve mitigation efforts for the impacts of smoke emissions. We used pre- and post-fire fuel loading measurements in 48 operational prescribed burns to estimate combustion completeness factors (CC) and emissions of fine particulates (PM2.5), carbon monoxide (CO) and carbon dioxide (CO2) in pine- and oak-dominated stands in the Pinelands National Re-serve of southern New Jersey. During 11 of the prescribed burns, we measured sensible heat flux and turbulence statistics on tower networks above the forest canopy. Fire behavior when fire fronts passed towers ranged from low-intensity backing fires to high-intensity head fires with some crown torching. Consumption of forest floor and understory vegetation were near-linear functions of pre-burn loading, and combustion of fine litter on the forest floor was the predominant source of emissions, even during head fires with some crowning activity. Tower measurements indicated that above-canopy sensible heat flux and TKE calculated at 1-minute intervals during the passage of fire fronts were strongly influenced by fire behavior. Low-intensity backing fires, regardless of forest type, had weaker enhancement of above-canopy air temperature, vertical and horizontal wind velocities, sensible heat fluxes and TKE compared to higher-intensity head and flanking fires. Sensible heat flux and TKE in buoyant plumes were unrelated during low in-tensity burns but more tightly coupled during higher intensity burns. The weak coupling during low intensity backing fires resulted in reduced rates of smoke transport and dispersion, and likely more prolonged periods of elevated surface concentrations. Our research facilitates more accurate estimates of PM2.5, CO and CO2 emissions from prescribed burns in the Pinelands, and it pro-vides a better understanding of the relationships between fire behavior, sensible heat fluxes and turbulence, and smoke dispersion in pine- and oak-dominated forests.

Citation

Fire

Volume

7

Issue

9

Pub Type

Journals

Download Paper

https://doi.org/10.3390/fire7090330

Local Download

Citation

Clark, K. , Gallagher, M. , Skowronski, N. , Heilman, W. , Charney, J. , Patterson, M. , Cole, J. , Mueller, E. and Hadden, R. (2024), Smoke Emissions and Buoyant Plumes above Prescribed Burns in the Pinelands National Reserve, New Jersey, Fire, [online], https://doi.org/10.3390/fire7090330, https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=958419 (Accessed December 27, 2024)