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The TreeMap 2016 dataset provides detailed spatial information on forest characteristics including number of live and dead trees, biomass, and carbon across the entire forested extent of the continental United States at 30 × 30m resolution, enabling analyses at finer scales where forest inventory is inadequate. We used a random forests machine learning algorithm to assign the most similar Forest Inventory Analysis (FIA) plot to each pixel of gridded LANDFIRE input data. The TreeMap 2016 methodology includes disturbance as a response variable, resulting in increased accuracy in mapping disturbed areas. Within-class accuracy was over 90% for forest cover, height, vegetation group, and disturbance code when compared to LANDFIRE maps. At least one pixel within the radius of validation plots matched the class of predicted values in 57.5% of cases for forest cover, 80.0% for height, 80.0% for tree species with highest basal area, and 87.4% for disturbance. A new feature of the dataset is that it includes linkages to select FIA data in an attribute table included with the TreeMap raster, allowing users to map summaries of 21 variables in a GIS. TreeMap estimates compared favorably with those from FIA at the state level for number of live and dead trees and carbon stored in live and dead trees. Study Implications: TreeMap 2016 provides a 30 × 30 m resolution gridded map of the forests of the continental United States. Attributes of each grid cell include a suite of forest characteristics including biomass, carbon, forest type, and number of live and dead trees. Users can readily produce maps and summaries of these characteristics in a GIS. The TreeMap also includes a database containing, for each pixel, a list of trees with the species, diameter, and height of each tree. TreeMap is being used in the private sector for carbon estimation and by land managers in the National Forest system to investigate questions pertaining to fuel treatments and forest productivity as well as Forest Plan revisions.

Thermocouples were used to measure gas temperatures as a function of distance to the edge of a rectangular burner. Experiments varied the energy release rate, burner aspect ratio, wind speed, and s...

espanolLa literatura existente sobre el uso de la segunda persona gira en torno a la relacion del publico con el texto. Los investigadores de la comunicacion interpersonal y los expertos en narracion y retorica sostienen que el uso de la segunda persona puede alterar los limites entre el autor, el texto y la audiencia en la interaccion social, la ficcion narrativa y la ficcion interactiva. La literatura sugiere que este uso de la segunda persona puede cambiar la forma en que se conecta con el publico, pero tambien crear un sentido de autoridad y aumentar la credibilidad de la narrativa. En este texto, recojo estas ideas y analizo como el uso de la segunda persona en el texto de los informativos de television puede tambien alterar la percepcion de la audiencia sobre los acontecimientos narrados y su involucracion en ellos. Tras una revision de la literatura existente sobre la perspectiva en segunda persona en los contextos de la interaccion interpersonal, la ficcion narrativa y los videojuegos interactivos, analizo la forma en que esas percepciones pueden utilizarse para comprender mejor el efecto que generan las noticias en television, adaptando un metodo y aplicandolo cualitativamente al texto de las noticias, y ubicando las conclusiones en la trayectoria conceptual de Michele Foucault y Edward Said. EnglishLiterature on the use of the second person perspective revolves around the relationship of the audience to the text. Interpersonal communications scholars, narratologists and rhetoricians argue that in social interaction, narrative fiction, and interactive fiction, the use of the second person point of view can alter the boundaries between author, text and audience. The literature suggests that the use of second person may change audiences' sense of connectedness, create a sense of authority, and enhance the believability of the narrative. In this paper, I take these insights and consider how the presence of second person perspective in the text of television news accounts may similarly alter audiences' perceptions of news events and their involvement in them. Following a review of second person perspective literature in the contexts of interpersonal interaction, narrative fiction and interactive video games, I explore how such insights can be usefully exploited to further understand television news effects, by adapting a method and applying it qualitatively to the text of news accounts and situating the findings in the conceptual trajectories of Michele Foucault and Edward Said.

Correlations of flame length L (or height) with the intensity of fires (kW/m2 for area sources or kW/m for line sources) have become foundational to fire behavior science (Byram 1959, Thomas 1963, Nelson and Adkins 1986, among others). Empirical data for these correlations have been based on fires fueled by wood cribs, paper strips, natural gas, and spreading fires at laboratory scales. The data and theory outlined by Thomas (1963, 1967) supported the idea that the horizontal dimension D of an infinite line fire could be neglected if L was much greater than D. Here we report on experiments with line-source fires where the energy release and flame zone dimensions were controlled independently (0.2≤L/D≤13.6), finding that increasing D significantly reduced L over the entire range of observations. Our flame length correlation was more similar to that of Thomas’ (1963) than Byram (1959) but the data clearly showed a strong dependency upon D. This finding suggests that fire behavior studies relying on correlations of L and fireline intensity must consider D to have an important effect on physical processes involved in wildfire behavior.

Our general objective in the present study is to develop tools to better describe the coupling between solid phase and gas phase processes that control the dynamics of flame spread in wildland fire problems. We focus on a modelling approach that resolves processes occurring at flame scales, i.e., the formation of flammable vapors from the biomass vegetation due to pyrolysis, the subsequent combustion of these fuel vapors with ambient air, the establishment of a turbulent flow because of heat release and buoyant acceleration, and the thermal feedback to the solid biomass through radiative and convective heat transfer. The modelling capability is based on a general-purpose Computational Fluid Dynamics (CFD) library called OpenFOAM and an in-house Lagrangian particle model that treats drying, thermal pyrolysis, oxidative pyrolysis and char oxidation using a one-dimensional porous medium formulation that allows descriptions of thermal degradation processes occurring during both flaming and smoldering combustion. The modelling capability is calibrated for pine wood and is first applied to simulations of fire spread across a surrogate vegetation bed corresponding to thin, monodisperse, cylindrical-shaped sticks of pine wood with prescribed particle and environmental properties (i.e., bed height, surface-to-volume ratio, packing ratio, moisture content, and wind velocity). While the model can be used in sloped terrain, the present simulations are limited to a flat ground surface. The current emphasis is on determining threshold conditions for successful spread, differences between the plume-dominated and wind-driven flame regimes, possible transitions to a steady or time-dependent flame structure, and differences in the relative weights of the flaming and smoldering regions.

A 30 × 30m-resolution gridded dataset of forest plot identifiers was developed for the conterminous United States (CONUS) using a random forests machine-learning imputation approach. Forest plots from the US Forest Service Forest Inventory and Analysis program (FIA) were imputed to gridded c2014 landscape data provided by the LANDFIRE project using topographic, biophysical, and disturbance variables. The output consisted of a raster map of plot identifiers. From the plot identifiers, users of the dataset can link to a number of tree- and plot-level attributes stored in the accompanying tables and in the publicly available FIA DataMart, and then produce maps of any of these attributes, including number of trees per acre, tree species, and forest type. Of 67,141 FIA plots available, 62,758 of these (93.5%) were utilized at least once in imputation to 2,841,601,981 forested pixels in CONUS. Continuous high-resolution forest structure data at a national scale will be invaluable for analyzing carbon dynamics, habitat distributions, and fire effects., Measurement(s) forested area Technology Type(s) machine learning Factor Type(s) biophysical variables • geographic location • forest type • forest height • forest percent cover Sample Characteristic - Environment vegetation layer Sample Characteristic - Location United States of America Machine-accessible metadata file describing the reported data: 10.6084/m9.figshare.13285904

The paper reports visualization of the flow of smoke over a flat surface inside of a low-speed wind tunnel. A heating plate flush mounted on the wind tunnel floor simulated a spreading line fire that produces uniform heat flux under constant wind speed condition. A paper-thin cloth was soaked with commercially available Vaseline and placed on top of the heating plate; when it is heated, it produced thick white smoke, ideal for flow visualization. Two sides and top of the wind tunnel were made of a transparent acrylic sheet that enabled LED and laser sheet light illumination of the flow. A still camera with a full-frame CMOS sensor was used to record time-series images of illuminated smoke flow patterns from different angles. From these images, the following four flow structures were identified: organized horizontal vortex flows, weak vortex flow interactions, strong vortex flow interactions (also described as the ‘transition regime’), and, turbulent flows. Previously developed scaling laws on forest fires were applied to find similarity in flow structures created by the current small-scale convective heat-transfer experiments and the USDA's mid-scale wind tunnel fire experiments.

The following study examines the role of streaklike coherent structures in mixed convection via a horizontal heated boundary layer possessing an unheated starting length. The three-dimensionality of flows in this configuration, which is regularly encountered in practical scenarios, has been experimentally probed using non-invasive detection methods. Experiments were conducted in a wind tunnel at the Missoula Fire Sciences Lab, and the wind speed was varied from 0.70 to 2.47 m/s. The buoyant source was varied significantly by either manipulating the surface temperature of a downstream hot plate or employing a diffusion flame. Streaks were visualized in the flow by means of infrared imaging or high speed video, and a novel detection algorithm was developed to quantify important properties and to spatially track these structures over time. Lognormal distributions of spacing were observed initially, and gradual deviations from this fit indicated a deviation from streaklike behavior. The onset of streaks was determined to be controlled by the pre-existing disturbances populating the incoming boundary layer. Further downstream, buoyant forces dominated the growth and deformation of these structures, whose length scale increased significantly. The width of structures was observed to asymptote to a stable value downstream, and this was determined to be a consequence of the finite distance over which heating was applied.

Live foliage for some tree and shrub species can support flaming fire spread at much higher moisture content than dead fuel materials. However, the role of live fuels in forest fires has been controversial in the past decades. Although ignition and spread statistical data for live and dead fuels exist in the literature, a clear understanding of the fundamental difference in the burning behavior is missing. To illuminate the role of live fuel on forest fire spreading, a laboratory ignition experiment was designed to examine the burning behavior of live Norway spruce needles. A Schlieren-Infrared combined measurement apparatus was developed with a spatial resolution of 0.75 mm and a time resolution of 0.0025 s, to visualize/measure the ignition behavior of live fuels. Schlieren and IR images revealed that the ejection of live fuel volatiles can alter the flame direction and induce previously unaccounted heating of the nearby fuel. Depending on the conditions, these interferences could heat and modify the heat flux received by the adjacent fuels. To analyze each of these outcomes, a scaling analysis using the law approach was performed. First, theoretical equations were developed and validated against a set of previously published experimental data. After the characteristic equations were verified, we used them to assess the volatile ejection phenomenon. We found that adjacent fuels were preheated by hot volatiles ejected from the heated live needle, and direct flame contact ignited the adjacent fuels. Our IR experiments confirmed the outcomes of the scaling analysis. The rapid ejection of volatiles was also found to propel burning needles far from the burning branch, resulting in micro-spotting.

Fuelbreaks are important proactive measures in wildfire prevention and mitigation. Among the most popular ones are the shaded fuelbreaks widely used in western countries and the green fire barriers developed in China forestry sector. While shaded fuelbreaks are considered a main strategy for reducing the distribution of fuel loads in a specific wildland zone, creating green fire barriers involves the dense planting of evergreen broad-leaved trees in a stripped area of flammable plant communities to prevent and block the spread of surface and crown fires. Unlike the shaded fuelbreak technique, the hazard reduction function of a green fire barrier originates from the traits of low-flammability trees and the unique structure formed by the prescribed plantation. Surface fire is mitigated by inhibiting the growth of surface fuels within the strip, whereas crown fire is attenuated and eventually blocked by significantly altering the heat transfer efficiency during an external fire attack. As often demonstrated in practice, the extensive application of this technique in fire-prone areas not only plays a role in mitigating the occurrence of wildfire and its impact on the local environment, but also somehow moderates the local meteorology and wind patterns. These two main fuelbreak approaches are key ecological fire protection techniques that simultaneously achieve prevention and control of accidental forest fires, forest health management and ecological maintenance. As two typical strategic measures, the effective fusion of these approaches can generate multiple economic treatment prescriptions for fire prevention and control at different vegetation scenes subjected to any potential heat sources. The derivatives of these fuelbreak approaches provide systematic tools for constructing both a fire resilient landscape and a green living environment with tolerable fire risk and controllable fire losses.

Streaklike coherent structures are consistently observed in boundary layer flames, but their role in modifying heat and mass transfer remains unknown. In the following experiment, a non-reactive thermal plume was employed to study analogous streaks in an environment where the local source of buoyancy could be directly modified. A horizontal hot plate was exposed to crossflow, and infrared thermography was successfully employed to capture thermal traces of streaks on the surface. Post-processing of surface temperature data enabled the quantification of important properties of streaks, such as location, spacing, width, and strength. The distribution of streak spacing was found to have a lognormal distribution. Mean streak spacing and width increased with downstream distance, indicating the amplification and aggregation of coherent structures. Streak spacing decreased when either the hot plate temperature increased from 150 °C to 300 °C or the wind speed increased from 0.5 to 1.2 m/s. Streaks were seen to modify the spanwise distribution of heat transfer to the surface, most notably when the hot plate temperature was increased from 150 °C to 300 °C.

Experiments were conducted to study the intermittent extension of flames from wind-driven line fires using stationary burners. These fires are thought to share similar features with propagating wildland fires, where forward pulsations of flame have been observed to quickly ignite material far ahead of the mean flame front. However, stationary burners offer the ability to study the movement of the flame and its heating processes in greater detail than a spreading fire. In these stationary experiments, propane gas was used as a fuel with different burner sizes, 25–30 cm wide and 5–25 cm long in the direction of the flow. A specially-built wind tunnel was used to provide a well-characterized laminar flow for the experimental area. The free-stream flow velocity, measured by a hot-wire anemometer, ranged in the experiments from 0.2 to 2.7 m/s. The shape of the flame was measured using a high-speed video camera mounted perpendicular to the apparatus. A method was developed to track the extension of the flame close to the surface, simulating flame contact with unburnt fuel downstream of the fire. This extension length was then measured frame by frame and frequencies of flame presence/absence determined as a function of downstream distance. The location of maximum pulsation frequency, x max , for each burner/wind configuration, was obtained using a level-crossing approach (essentially the variable-interval time-average (VITA) method). Further study indicates that x max can be well estimated using mean flame properties. Probability distributions describing the location of the flame over time also showed that, the probability the flame extends far beyond the mean flame front is sensitive to increasing ambient winds and fire size.

Observations of coherent structures in boundary layer flames, particularly wildland fires, motivated an investigation on instabilities in a boundary layer flame. This experimental study examined streaklike structures in a stationary diffusion flame stabilized within a laminar boundary layer. The incoming flow was characterized with a hotwire anemometer, and locations of the flame streaks were found to align with pre-existing velocity perturbations. These upstream disturbances enabled stabilization of flame streaks, which could then be probed with point measurements. Flame streaks were seen to amplify with the streamwise development of the fire, and this growth was quantified via thermocouple measurements. Temperature mapping of the flame streaks indicated a temperature rise in the flame streaks, while the region in between these streaks, the trough, was seen to decrease in temperature. The heat flux to the surface was measured with a total heat flux gauge. Measurements were taken below the flame streaks and below the regions between the streaks (i.e., troughs). At all measurement locations, the heat flux below the troughs was found to be higher. This was likely a function of the flame standoff distance, and indicated that the flame streaks were acting to modify the spanwise distribution of heat flux. The presence of instabilities had a significant effect on the spanwise distribution of heat transfer. Instantaneous properties in boundary layer combustion can vary significantly due to three-dimensional effects, and this may have significant implications for describing and modeling boundary layer combustion.

The ability to rapidly estimate wind speed beneath a forest canopy or near the ground surface in any vegetation is critical to practical wildland fire behavior models. The common metric of this wind speed is the “mid-flame” wind speed, UMF. However, the existing approach for estimating UMF has some significant shortcomings. These include the assumptions that both the within-canopy wind speed and the canopy structure are uniform with depth (z) throughout the canopy and that the canopy roughness length (z0) and displacement height (d) are the same regardless of canopy structure and foliage density. The purpose of this study is to develop and assess a model of canopy wind and Reynolds stress that eliminates these shortcomings and thereby provide a more physically realistic method for calculating UMF. The present model can be used for canopies of arbitrary plant surface distribution and leaf area, and the single function that describes the within-canopy wind speed is shown to reproduce observed canopy wind speed profiles across a wide variety of canopies. An equally simple analytical expression for the within-canopy Reynolds stress, [Formula: see text], also provides a reasonable description of the observed vertical profiles of Reynolds stress. In turn, [Formula: see text] is used to calculate z0 and d. Tests of operational performance are also discussed.

An experimental study was conducted to understand the intermittent heating behavior downstream of a gaseous line burner under forced flow conditions. While previous studies have addressed time-averaged properties, here measurements of the flame location and intermittent heat flux profile help to give a time-dependent picture of downstream heating from the flame, useful for understanding wind-driven flame spread. Two frequencies are extracted from experiments, the maximum flame forward pulsation frequency in the direction of the wind, which helps describe the motion of the flame, and the local flame-fuel contact frequency in the flame region, which is useful in calculating the actual heat flux that can be received by the unburnt fuel via direct flame contact. The forward pulsation frequency is obtained through video analysis using a variable interval time average (VITA) method. Scaling analysis indicates that the flame forward pulsation frequency varies as a power-law function of the Froude number and fire heat-release rate, fF ~(Fr/Q*1/2)0.4. For the local flame-fuel contact frequency, it is found that the non-dimensional flame-fuel contact frequency fC+ remains approximately constant before the local Rix reaches 1, e.g., attached flames. When Rix > 1, fC+ decreases with local as Rix flames lift up. A piece-wise function was proposed to predict the local flame-fuel contact frequency including the two Rix scenarios. Information from this study helps to shed light on the intermittent behavior of flames under wind, which may be a critical factor in explaining the mechanisms of forward flame spread in wildland and other similar wind-driven fires.

Recent wildland fire disasters have attracted interest from a variety of disciplines seeking to reduce impacts of fire on people and natural resources. Architecture, insurance and reinsurance, city and county government, and engineering sectors have contributed ideas to mitigate or avoid damage during wildland fires. This paper examines the modern wildland fire system in terms of the historical context for wildland fire, primarily in the US, and discusses some of the characteristics of this system and its human culture that affect the potential impact of innovations and engineering technologies.

Many wildland fire models assume radiation heat transfer controls fuel particle ignition. However, evidence suggests that radiation is insufficient to ignite the predominantly small, thin fuel particles in wildlands and that convective heating by flame contact is a critical component. Here, convective ignition was studied using an apparatus containing two 6.5 kW electrical heaters to heat air from 600 °C to 800 °C. Steel screens straightened the flow and provided background radiant heat. This apparatus produced autoignition of dry red oak cylinders and disks. Cylinder diameter was varied from 0.64 to 1.91 cm and length from 2.5 to 7.5 cm. Disk diameters varied from 2.54 to 5.08 cm and 1 to 4 mm thick. The airflow rate varied slightly from 1.55 to 1.71 m/s due to the density difference. A simplified analytical model was developed that predicted the measured times reasonably well for air temperatures of 700 °C and above.

We used simulation modeling to assess potential climate change impacts on wildfire exposure in Italy and Corsica (France). Weather data were obtained from a regional climate model for the period 1981–2070 using the IPCC A1B emissions scenario. Wildfire simulations were performed with the minimum travel time fire spread algorithm using predicted fuel moisture, wind speed, and wind direction to simulate expected changes in weather for three climatic periods (1981–2010, 2011–2040, and 2041–2070). Overall, the wildfire simulations showed very slight changes in flame length, while other outputs such as burn probability and fire size increased significantly in the second future period (2041–2070), especially in the southern portion of the study area. The projected changes fuel moisture could result in a lengthening of the fire season for the entire study area. This work represents the first application in Europe of a methodology based on high resolution (250 m) landscape wildfire modeling to assess potential impacts of climate changes on wildfire exposure at a national scale. The findings can provide information and support in wildfire management planning and fire risk mitigation activities.

We describe a Web-GIS wildfire prevention and management platform (AEGIS) developed as an integrated and easy-to-use decision support tool to manage wildland fire hazards in Greece (http://aegis.aegean.gr). The AEGIS platform assists with early fire warning, fire planning, fire control and coordination of firefighting forces by providing online access to information that is essential for wildfire management. The system uses a number of spatial and non-spatial data sources to support key system functionalities. Land use/land cover maps were produced by combining field inventory data with high-resolution multispectral satellite images (RapidEye). These data support wildfire simulation tools that allow the users to examine potential fire behavior and hazard with the Minimum Travel Time fire spread algorithm. End-users provide a minimum number of inputs such as fire duration, ignition point and weather information to conduct a fire simulation. AEGIS offers three types of simulations, i.e., single-fire propagation, point-scale calculation of potential fire behavior, and burn probability analysis, similar to the FlamMap fire behavior modeling software. Artificial neural networks (ANNs) were utilized for wildfire ignition risk assessment based on various parameters, training methods, activation functions, pre-processing methods and network structures. The combination of ANNs and expected burned area maps are used to generate integrated output map of fire hazard prediction. The system also incorporates weather information obtained from remote automatic weather stations and weather forecast maps. The system and associated computation algorithms leverage parallel processing techniques (i.e., High Performance Computing and Cloud Computing) that ensure computational power required for real-time application. All AEGIS functionalities are accessible to authorized end-users through a web-based graphical user interface. An innovative smartphone application, AEGIS App, also provides mobile access to the web-based version of the system.

Wood cribs are often used as ignition sources for room fire tests and the well characterized burning rates may also have applications to wildland fires. The burning rate of wildland fuel structures, whether the needle layer on the ground or trees and shrubs themselves, is not addressed in any operational fire model and no simple model exists. Several relations exist in the literature for the burning rate of wood cribs, but the cribs used to generate them were built with fairly limited geometries. This work explores the burning rate of cribs with a wide variety of geometries and aspect ratios in the loosely-packed regime to evaluate the rigor of several correlations from the literature. Specifically, stick thicknesses ranged from 0.16 cm to 1.27 cm and lengths from 6.4 cm to 61.0 cm resulting in aspect ratios (stick length/thickness) from 10 cm to 160. As wildland fuel beds occur both directly on the ground and suspended in the air, the effect of the vertical gap between the ground and crib base was also examined. The critical vertical gap was shown to be larger than previously thought (7.6 cm for all cribs) and a function of the aspect ratio. It was quite apparent that as the aspect ratio increases, a significant portion of the required oxidizer comes from the bottom of the crib. A relation is then found to adjust the predicted values for the reduction in burning rate due to insufficient vertical gap.

Wood cribs are often used as ignition sources for room fire tests. A wood crib may also apply to studies of burning rate in wildland fires, because wildland fuel beds are porous and three dimensional. A unique aspect of wildland fires is the ubiquitous presence of wind. However, very little is known about what effect the increased ventilation has on the burning rate of cribs in either the densely- or loosely-packed regime. Experiments were performed with seven cribs designs with a range of porosities and two fuel element sizes: 0.64 cm and 1.27 cm. These cribs were burned in a wind tunnel with wind speeds ranging from 0 m/s to 0.7 m/s. Changes in the observed flame structure and burning patterns with wind are noted and discussed. The effect of wind on the burning rate was seen to depend on the fuel thickness. At the highest wind speed tested, cribs built with the 1.27 cm sticks showed a 6.5% to 61.5% increase in burning rate depending on porosity. Cribs built with the 0.64 cm sticks showed a decrease of 36.7% to 60.6% that was relatively constant with wind speed. Possible mechanisms of these changes are discussed. Future work will include further testing to clarify the causes of these trends.

Experiments were conducted to examine the potential for rifle bullets to ignite organic matter after impacting a hard surface. The tests were performed using a variety of common cartridges (7.62 × 51 [.308 Winchester (The use of tradenames is provided for informational purposes only and does not constitute an endorsement by the U.S. Department of Agriculture.)], 7.62 × 39, 7.62 × 54R, and 5.56 × 45 [.223 Remington]) and bullet materials (steel core, lead core, solid copper, steel jacket, and copper jacket). Bullets were fired at a steel plate that deflected fragments downward into a collection box containing oven-dried peat moss. We found that bullets could reliably cause ignitions, specifically those containing steel components (core or jacket) and those made of solid copper. Lead core-copper jacketed bullets caused one ignition in these tests. Thermal infra-red video and temperature sensitive paints suggested that the temperature of bullet fragments could exceed 800°C. Bullet fragments collected from a water tank were larger for solid copper and steel core/jacketed bullets than for lead core bullets, which also facilitate ignition. Physical processes are reviewed with the conclusion that kinetic energy of bullets is transformed to thermal energy by plastic deformation and fracturing of bullets because of the high-strain rates during impact. Fragments cool rapidly but can ignite organic matter, particularly fine material, if very dry and close to the impact site.

We develop the idea of risk transmission from large wildfires and apply network analyses to understand its importance on a 0.75 million ha US national forest. Wildfires in the western US frequently burn over long distances (e.g., 20–50 km) through highly fragmented landscapes with respect to ownership, fuels, management intensity, population density, and ecological conditions. The collective arrangement of fuel loadings in concert with weather and suppression efforts ultimately determines containment and the resulting fire perimeter. While spatial interactions among land parcels in terms of fire spread and intensity have been frequently noted by fire managers, quantifying risk and exposure transmission has not been attempted. In this paper we used simulation modeling to quantify wildfire transmission and built a transmission network consisting of land designations defined by national forest management designations and ownership. We then examined how a forest-wide fuel management program might change the transmission network and associated metrics. The results indicated that the size, shape, and fuel loading of management designations affected their exposure to wildfire from other designations and ownerships. Manipulating the fuel loadings via simulated forest fuel treatments reduced the wildfire transmitted among the land designations, and changed the network density as well. We discuss how wildfire transmission has implications for creating fire adapted communities, conserving biodiversity, and resolving competing demands for fire-prone ecosystem services.

The mechanism of flame propagation in fuel beds of wildland fires is important to understand in order to quantify fire spread rates. Fires spread by radiative and convective heating and in some cases require direct flame contact to achieve ignition. The flame in an advancing fire is unsteady and turbulent, making study of intermittent flames in complex fuels difficult. A 1.83 m tall, 0.61 m wide vertical wall fire, in which ethylene fuel is slowly fed through a porous ceramic, is modeled to investigate unsteady turbulent flames in a controlled environment. Three fuel flow rates of 235, 390, and 470 L/min are considered. Simulations of this configuration are performed using a spatial formulation of the one-dimensional turbulence (ODT) model which is able to resolve individual flames (a key property of this model) and has been shown to provide turbulent statistics that compare well with experimental data for a number of flow configurations including wall fires. In the ODT model diffusion–reaction equations are solved along a notional line of sight perpendicular to the wall that is advanced vertically. Turbulent advection is modeled through stochastic domain mapping processes. A new Darrieus–Landau combustion instability model is incorporated in the ODT eddy selection process. The ODT model is shown to capture the evolution of the flame and describe the intermittent properties at the flame/air interface. Simulations include radiation and soot effects and are compared to experimental temperature measurements. Simulated mean temperatures differ from the experiments by an average of 63 K over all measurement points for the three fuel flow rates. Predicted root mean square temperature fluctuations capture the trends in the experimental data, but overestimate the raw experimental values by a factor of two. This difference is discussed using thermocouple response and heat transfer correction models. Simulated velocity, soot, and radiation properties are also reported.

A series of fire experiments were carried out in a wind tunnel at the United States Forest Service's Fire Science Laboratory in Missoula, Montana. The experiments involved tines cut out of pieces of cardboard. The pieces were laid out in comb-like strips parallel to each other along a testbed. They were ignited at the windward end of the testbed. The progress of the fire was monitored by thermocouples, recording temperature, set out equidistantly up the middle of the testbed. Goals of the experiment included improved understanding of wildfire spread and the development of practical tools for wild land fire managers to employ. There was to be a search for regular pulsing in the series and any other interesting phenomena. This paper presents the results of a variety of exploratory data analyses meant to elicit information concerning the series before commencing probability modeling. Published 2014. This article is a U.S. Government work and is in the public domain in the USA.

The current study focuses on coupled dynamics and resultant geometry of fireline segments of various ignition lengths. As an example, for ignition lines of length scales typical for field experiments, fireline curvature is the result of a competition between the head fire and the flanks of the fire. A number of physical features (i.e. buoyancy and wind field divergence for example) arise in and around an incipient fire that defines the shape and spreading pattern of the flame zone. These features are explored using a numerical atmospheric dynamics model HIGRAD, and wildfire combustion physics model FIRETEC. HIGRAD/FIRETEC was designed to investigate wildfires and their interactions with the environment. In this study, the model was used to simulate grass fires that were initiated with a finite length, straight ignition line in homogeneous fuels. The dynamic evolutions of these firelines were analyzed to understand the individual events that evolve a wildfire. By understanding each individual process and how it interacts with other processes, information can be extracted to develop a theory about the mechanisms that combine to produce the observed wildfire behavior. In the current study, the flow field in the region of the simulated fires developed structures consistent with multiple buoyancy-induced vortex pairs. The series of stream-wise vortex pairs produce a regular alternating pattern of up-wash and down-wash zones, which allow air to penetrate the flame zone through troughs created in downwash regions. Consequently, this periodicity in the flow field within the fire resulted in a pattern of residual combustion where prolonged burning occurred in the up-wash zones separated by near-complete fuel depletion in the downwash zones. Some explanation is provided for why increased ignition line length leads to increased rate of spread (ROS) with some asymptotic limit.

Recent fire seasons in the western United States are some of the most damaging and costly on record. Wildfires in the wildland-urban interface on the Colorado Front Range, resulting in thousands of homes burned and civilian fatalities, although devastating, are not without historical reference. These fires are consistent with the characteristics of large, damaging, interface fires that threaten communities across much of the western United States. Wildfires are inevitable, but the destruction of homes, ecosystems, and lives is not. We propose the principles of risk analysis to provide land management agencies, first responders, and affected communities who face the inevitability of wildfires the ability to reduce the potential for loss. Overcoming perceptions of wildland-urban interface fire disasters as a wildfire control problem rather than a home ignition problem, determined by home ignition conditions, will reduce home loss.

The financial impact of wildfire management within the USDA Forest Service challenges the ability of the agency to meet societal demands and maintain forest health. The extent of this financial crisis has been attributed to historical and continuing fire management practices, changing climatic conditions, and increasing human development in fire-prone areas, as well as the lack of financial accountability of fire managers and misaligned incentive structures. In this article, we focus on incentives related to cost containment. We review the literature on the incentive structure facing wildfire managers and describe how the incentive structure does not sufficiently reward cost containment. We then cover a range of possible approaches to promote cost containment, culminating in a novel solution premised on the application of actuarial principles to wildfire budgetary planning that we believe most closely aligns with the Forest Service's transition to risk-based management paradigms and that most comprehensively incentivizes containment across the spectrum of wildfire management activities. We illustrate through a proof of concept case study how risk-based performance measures would be calculated and compare our results with historic suppression expenditures. Preliminary results suggest that our simulation model performs well in a relative sense to identify high- and low-cost forests, and we detail modeling improvements to refine estimates. We then illustrate potential extension to an actuarial system, which would further incentivize appropriate risk management and cost containment across the fire management continuum. We address the strengths and weaknesses of the proposed approaches, including potential roadblocks to implementation, and conclude by summarizing our major findings and offer recommen- dations for future agency direction. FOR .S CI. 59(1):63-77.

Maps of the number, size, and species of trees in forests across the western United States are desirable for many applications such as estimating terrestrial carbon resources, predicting tree mortality following wildfires, and for forest inventory. However, detailed mapping of trees for large areas is not feasible with current technologies, but statistical methods for matching the forest plot data with biophysical characteristics of the landscape offer a practical means to populate landscapes with a limited set of forest plot inventory data. We used a modified random forests approach with Landscape Fire and Resource Management Planning Tools (LANDFIRE) vegetation and biophysical predictors to impute plot data collected by the US Forest Service's Forest Inventory Analysis (FIA) to the landscape at 30-m grid resolution. This method imputes the plot with the best statistical match, according to a “forest” of decision trees, to each pixel of gridded landscape data. In this work, we used the LANDFIRE data set for gridded input because it is publicly available, offers seamless coverage of variables needed for fire models, and is consistent with other data sets, including burn probabilities and flame length probabilities generated for the continental United States. The main output of this project is a map of imputed plot identifiers at 30 × 30 m spatial resolution for the western United States that can be linked to the FIA databases to produce tree-level maps or to map other plot attributes. In addition, we used the imputed inventory data to generate maps of forest cover, forest height, and vegetation group at 30 × 30 m resolution for all forested pixels in the western United States, as a means of assessing the accuracy of our methodology. The results showed good correspondence between the target LANDFIRE data and the imputed plot data, with an overall within-class agreement of 79% for forest cover, 96% for forest height, and 92% for vegetation group.