Wildfires pose a growing threat for communities along the wildland-urban interface (WUI) around the world driven by a changing climate and expanding urban areas. One of the primary mechanisms by which fires can spread in the WUI are firebrands, airborne embers capable of acting as ignition sources carried in the airstream. Many studies have been conducted on the generation and transport of firebrands, but limited work has been conducted to quantify the heat transfer of firebrand piles to surfaces. A series of three studies are presented here exploring the heat transfer, burning, and material ignition of firebrands. In the first study, the differences between firebrands from structure and vegetation sources was compared. It was found that an ash layer in the vegetation firebrands reduced the heat and mass transfer. In the second study, impact of the surface geometries that firebrands accumulate on was explored. It was found that wall and corner configurations reduced the heat transfer the most and caused piles to burn from the wall surfaces outwards. Flat plate and decking configurations had the highest heat flux due to the lack of flow obstruction. In the final study, a framework was developed for predicting the material ignition resistance reliability exposed to a smoldering firebrand pile. The exposure was based on empirical relations for the heat flux from piles as a function of pile height, porosity, and wind speed. Cone calorimeter data was used to generate material thermal and ignition properties. With these inputs, the framework was used to predict the potential for material ignition thus circumventing the need for costly firebrand tests. This collection of studies provides evidence of the factors that drive firebrand burning behavior and heat transfer and links those aspects to the potential for ignition of construction materials. / Doctor of Philosophy / Wildland-urban interface (WUI) fires pose a growing threat for communities around the world driven by a changing climate and expanding urban areas. A particularly dangerous way that fires can spread long distances is via firebrands, burning particles that splinter off of trees or buildings that can be blown long distances by the wind. These firebrands can land onto surfaces like buildings and ignite those surfaces, causing new fires called spot fires. The science behind how firebrands ignite new surfaces is not well-developed, and there is no broad tool that can be used to predict whether a material or a building will ignite given certain conditions. The research presented here aims to address that lack of understanding by approaching the problem systematically, breaking down the individual driving elements of firebrand burning. First, the difference in heat transfer and burning behavior between firebrands from structures and from vegetation was explored. Second, the impact of various surface geometries was explored. The surface geometry of where the firebrands accumulate also influences the heat transfer of the firebrands. Finally, a framework for predicting the material reliability of materials to firebrand exposure is presented. Experimental correlations for firebrand burning based on pile parameters were generated and used to predict the heat fluxes from piles. The framework used material ignition data from cone calorimeter experiments to predict how materials would respond under thermal exposure. The framework compares the predicted exposure with the material ignition data to calculate the reliability. This collection of studies provides insight on the many factors that drive firebrand burning behavior and heat transfer and links those aspects to the ignition of materials.

Thesis (Ph. D.)--University of Oregon, 2007. / Typescript. Includes vita and abstract. Includes bibliographical references (leaves 183-205). Also available for download via the World Wide Web; free to University of Oregon users.

Thesis (M.S.)--Humboldt State University, 2009. / Includes bibliographical references (leaves 48-53). Also available via Humboldt Digital Scholar.

Thesis (M.S.)--Brigham Young University. Dept. of Chemical Engineering, 2005. / Includes bibliographical references (leaves 89-95).

In this dissertation, I combined a scenario-based, standard-response optimization model with a stochastic simulation model to improve the efficiency of the deployment of initial attack firefighting resources on wildland fires in California and the Republic of Korea. The optimization model minimizes the expected number of fires that do not receive a standard response���defined as the number of resources by type that must arrive at the fire within a specified time limit���subject to budget and station capacity constraints and uncertainty about the daily number and location of fires. The simulation model produces a set of fire scenarios in which a combination of fire count, fire locations, fire ignition times, and fire behavior occur. Compared with the current deployment, the deployment obtained with optimization shifts resources from the planning unit with the highest fire load to the planning unit with the highest standard response requirements. Resource deployments that result from relaxing constraints on station capacity achieve greater containment success by encouraging consolidation of resources into stations with high dispatch frequency, thus increasing the probability of resource availability on high fire count days. I extended the standard response framework to examine how a policy priority influences the optimal spatial allocation and performance of initial attack resources. I found that the policy goal of a fire manager changes the optimal spatial allocation of initial attack firefighting resources on a heterogeneous landscape, especially, for the socio-economic value of a potential fire location. Furthermore, I investigated the tradeoff between the number of firefighting resources and the level of fire ignition prevention efforts mitigating the probability of human-made fires in the Republic of Korea where most fires are caused by human activities. I found that fire ignition prevention is as cost-effective as initial attack resources given the current budget in the Republic of Korea on reducing the expected number of fires not receiving the standard response. From the comparison of the California and Republic of Korea cases, I can identify "rules of thumb" to be followed when allocating IA resources in particular ecological and policy settings. / Graduation date: 2013

Thesis (Ph. D.)--University of Montana, 2006. / Title from title screen. Description based on contents viewed Mar. 30, 2007. Includes bibliographical references (p. 142-151).

Includes bibliographical references. / Cover title. "February 2003." 4/8/03: Also available via Internet.

published_or_final_version / Environmental Management / Master / Master of Science in Environmental Management

70 % of the worlds most expensive wildfireshas occurred since year 2003. This is a clear example of that wildfires arean increasingly growing problem which demands new solutions. Some of the most prominent problems of fighting wildfires are the harsh terrainand limited accessibility, the lack of communication and difficulties in creating an overview off the scene and predict how the wildfire will develop. These problems are all factors which I have tried to focus on in my degree project, the Trition. By doing thoroughly research about wildfires and by gathering information and inspiration from other areas, such as the military, it was possible to see the problems of wildfires in a more problem solving perspective. Ideas and forms were generated through unrestrictive sketching and created sketch models.The Trition is a terrain fire truck that serves as a response vehicle, with exceptionally good off-road mobility and that always can be first at the scene. The Trition also serves as a command central which can organise the enormous operations that big fires demands. By having a mobile and multifunctional command central it is possible to always have the latest data about the scene and plan the wildfire fighting in the most efficient way.The Trition is equipped with a drone on its roof. The drone can take off and sweep the area, collecting data which gives the firefighters a good overview and that help to predict the wildfire, such as wind speed and the terrain incline. The drone also has an important preventing function. By regularly sweeping inhabitant areas, the drones infrared camera can detect wildfires earlyon and alert the Trition for an early intervention.

We developed a fully-coupled meso-scale model WRF-Chem-SMOKE by incorporating a selection of smoke emission models and improving the representations of aerosol-cloud interactions in the microphysics scheme. We find that the difference in smoke emissions between different datasets, even in one fire cluster, could lead to significant discrepancies in modeled AODs. The integrated smoke emission dataset improves the prediction of modeled AODs. We find that the modeled cloud properties and precipitation are extremely sensitive to the smoke loadings. Higher smoke loadings suppress precipitation initially, because of smoke-induced reduction of the collision-coalescence and riming processes, but ultimately cause an invigoration of precipitation.