Smoke plumes associated with wildland fires are difficult to characterize due to the non-linear behavior of the variables involved. Plume chemistry is largely modeled using emission factors to represent the relative trace gas and aerosol species emitted. Plume dynamics are modeled based on assumptions of plume vertical distribution and atmospheric dispersion. In the studies presented here, near and in-source measurements of emissions from prescribed burns are used to characterize the variability of emission factors from low-intensity fires. Emissions factors were found to be in the same range as those from other, similar studies in the literature and it appears that the emission factors may be sensitive to small differences in surface conditions such as fuel moisture, surface wind speed, and the ratio of live to dead fuels. We also used two coupled fire atmosphere models, which utilize the Weather Research and Forecasting (WRF) model called WRF-Fire and WRF-Sfire, to investigate the role that atmospheric stability plays in influencing plume rise as well as developing a technique for assessing plume rise and the vertical distribution of pollutants in regional air quality models. Plume heights, as well as rate of growth of the fire, were found to be sensitive to atmospheric stability while fire rate of spread was not. The plume center-of-mass technique was demonstrated to work well but has slightly low estimates compared to observations.

Excerpt from Smoke Plume Trajectory From in Situ Burning of Crude Oil in Alaska: Field Experiments and Modeling of Complex Terrain The uncertainty of aloft model predictions is largely a function of the uncertainty in the meteorological conditions and fire emission rates. The factor of safety of 2 that had been applied to the downwind distance predictions as an estimate of uncertainty for the original flat terrain modeling results has been replaced by more appropriate ways of assessing uncertainty, and these will be presented in the report. The ventilation factor, which is the product of the wind speed and mixing layer depth used to characterize the dispersive potential of the atmosphere, is a reasonably good indicator of expected ground level concentration of smoke or combustion products from a large burn. This is true of both flat and complex terrain. Smoke particulate is by far the most likely combustion product of crude oil burning to exceed ambient air quality standards at ground level beyond a few hundred meters from the fire. About the Publisher Forgotten Books publishes hundreds of thousands of rare and classic books. Find more at www.forgottenbooks.com This book is a reproduction of an important historical work. Forgotten Books uses state-of-the-art technology to digitally reconstruct the work, preserving the original format whilst repairing imperfections present in the aged copy. In rare cases, an imperfection in the original, such as a blemish or missing page, may be replicated in our edition. We do, however, repair the vast majority of imperfections successfully; any imperfections that remain are intentionally left to preserve the state of such historical works.