The contribution of duff consumption to fire emissions and air pollution of the Rough Ridge Fire

Abstract

It is typically difficult to burn duff because of high fuel moisture; however, under persistent drought conditions, duff will burn readily. This study investigates the burning of a deep duff layer by the 2016 Rough Ridge Fire, in the southern United States, under drought conditions and evaluates the contribution of duff consumption to fire emissions and air pollution. Fuel loading was measured and used to evaluate the BlueSky framework. Smoke was simulated for three fuel loading and moisture scenarios of field measurement, BlueSky estimated fuel loading, and a hypothetical moist condition. The measured fuels had a very deep duff layer that had accumulated over decades due to the lack of historical fires, most of which was burned by the fire. The burning of this deep duff layer contributed substantially to the increased fire emissions at the fire site and the air pollution in metro Atlanta. In contrast, BlueSky under-predicted duff loading and fire emissions. As a result, no major air pollution episodes were predicted for metro Atlanta. The high-moisture scenario also failed to produce a major air-pollution episode within Atlanta, which highlights the contribution of the drought to the air-pollution episode within Atlanta.