Modeling Multiple-Core Updraft Plume Rise for an Aerial Ignition Prescribed Burn by Coupling Daysmoke with a Cellular Automata Fire Model

Abstract

Abstract:Smoke plume rise is critically dependent on plume updraft structure. Smoke plumes from landscape burns (forest and agricultural burns) are typically structured into "sub-plumes" or multiple-core updrafts with the number of updraft cores depending on characteristics of the landscape, fire, fuels, and weather. The number of updraft cores determines the efficiency of vertical transport of heat and particulate matter and therefore plume rise. Daysmoke, an empirical-stochastic plume rise model designed for simulating wildland fire plumes, requires updraft core number as an input. In this study, updraft core number was gained via a cellular automata fire model applied to an aerial ignition prescribed burn conducted at Eglin AFB on 6 February 2011. Typically four updraft cores were simulated in agreement with a photo-image of the plume showing three/four distinct sub-plumes. Other Daysmoke input variables were calculated including maximum initial updraft core diameter, updraft core vertical velocity, and relative emissions production. Daysmoke simulated a vertical tower that mushroomed 1,000 m above the mixing height. Plume rise was validated by ceilometer. Simulations with two temperature profiles found 89-93 percent of the PM 2.5 released during the flaming phase was transported into the free atmosphere above the mixing layer. The minimal ground-level smoke concentrations were verified by a small network of particulate samplers. Implications of these results for inclusion of wildland fire smoke in air quality models are discussed.

Fire emission uncertainties and their effect on smoke dispersion predictions: a case study at Eglin Air Force Base, Florida, USA

“…This prescribed burn was simulated using Daysmoke, an empirical-stochastic fire plume model developed specifically for prescribed burns in the south-eastern US (Achtemeier et al 2011). Daysmoke requires emission rates, updraft core numbers (the number of discernable, organised, rising plumes in a burn), updraft core vertical velocities, maximum initial updraft core diameters and vertical profiles of meteorological data as inputs for every 12 min (Achtemeier et al 2011;Achtemeier et al 2012). The ambient vertical temperature profile was used in the calculations that determine plume stability and plume height.…”

“…Time profile of heat release and relative emission rates Location and number of updraft cores, updraft core vertical velocities, maximum initial updraft core diameters, fractional emission rates and the percentage of total emission per unit time were all obtained from a cellular automata fire spread model called Rabbit Rules (Achtemeier et al 2012). Twelve-min averages of these variables (Fig.…”

“…Time-dependent updraft core vertical velocity, updraft core number, maximum initial updraft core diameter and fractional emission rates produced by Rabbit Rules(Achtemeier et al 2012).…”

Applicability of an integrated plume rise model for the dispersion from wild-land fires

“…The convective heat release can also be unevenly distributed across the landscape (e.g. Liu et al, 2010;Achtemeier et al, 2012).…”

The Weather Conditions for Desired Smoke Plumes at a FASMEE Burn Site

“…Recent smoke models modify this scheme, but evaluations have been made mainly against wildfires. The presence of multiple plume updrafts makes plume rise modeling more complex [15]. Many smoke models are decoupled from dynamical fire behavior modeling and do not utilize high-resolution and time varying spatial distribution of heat release across the landscape, which are critical for smoke structure and properties such as multiple updrafts and plume rise.…”