Scott L. Goodrick

Observing The Dynamics Of Wildland Grass Fires: FireFlux -A Field Validation Experiment

The first comprehensive set of in situ measurements of turbulence and dynamics in an experimental wildland grass fire should help improve fire models.

Coherent vertical structures in numerical simulations of buoyant plumes from wildland fires

The structure and dynamics of buoyant plumes arising from surface-based heat sources in a vertically sheared ambient atmospheric flow are examined via simulations of a three-dimensional, compressible numerical model. Simple circular heat sources and asymmetric elliptical ring heat sources that are representative of wildland fires of moderate intensity are considered. Several different coherent vortical structures that dominate the plume structure and evolution are evident in the simulations, and these structures correspond well with those observed in plumes from wildland fires. For the circular source, these structures include: (i) a counter-rotating vortex pair aligned with the plume trajectory that is associated with a bifurcation of the plume, (ii) transverse shear-layer vortices on the upstream face of the plume, and (iii) vertically oriented wake vortices that form periodically with alternating sign on either side of the downstream edge of the plume base. For the elliptical ring source, a streamwise counter-rotating vortex pair is apparent on each flank, and a transverse horizontal vortex is observed above the head of the source. In all simulations the plume cross section is represented poorly by a self-similar Gaussian distribution.

Modelling smoke transport from wildland fires: a review

Among the key issues in smoke management is predicting the magnitude and location of smoke effects. These vary in severity from hazardous (acute health conditions and drastic visibility impairment to transportation) to nuisance (regional haze), and occur across a range of scales (local to continental). Over the years a variety of tools have been developed to aid in predicting smoke effects. This review follows the development of these tools, from various indices and simple screening models to complex air quality modelling systems, with a focus on how each tool represents key processes involved in smoke transport.

Modification of the Fosberg fire weather index to include drought

The Fosberg fire weather index is a simple tool for evaluating the potential influence of weather on a wildland fire based on temperature, relative humidity and wind speed. A modification to this index that includes the impact of precipitation is proposed. The Keetch-Byram drought index is used to formulate a ‘fuel availability’ factor that modifies the response of the fire weather index. Comparisons between the original and modified indices are made using historical fire data from the Florida Division of Forestry. The addition of the fuel availability factor helps increase the utility of the fire weather index as it offers an improved relationship between the index and area burned.

Smoke incursions into urban areas: simulation of a Georgia prescribed burn

This study investigates smoke incursion into urban areas by examining a prescribed burn in central Georgia, USA, on 28 February 2007. Simulations were conducted with a regional modeling framework to understand transport, dis- persion, and structure of smoke plumes, the air quality effects, sensitivity to emissions, and the roles of burn management strategy in mitigating the effects.The results indicate that smoke plumes first went west, but turned north-west at noon owing to a shift in wind direction. The smoke then invaded metropolitan Atlanta during the evening rush hour. The plumes caused severe air quality problems in Atlanta. Some hourly ground PM2.5 (particulate matter not greater than 2.5 µm in diameter) concentrations at three metropolitan Atlanta locations were three to four times as high as the daily (24-h) US National Ambi- ent Air Quality Standard. The simulated shift in the smoke transport direction and the resultant effects on air quality are sup- ported by the satellite and ambient air measurements. Two sensitivity simulations indicate a nearly linear relation between the emission intensities and PM2.5 concentrations. Two other simulations indicate that the impacts on air quality for the residents of Atlanta during the evening commute could have been reduced if the starting time of the burn had been altered.

Florida wildfire activity and atmospheric teleconnections

Since 1991, the Florida Division of Forestry has been making seasonal fire severity forecasts based on a relationship between area burned in Florida and El Nino–Southern Oscillation (ENSO). The present study extends the original analysis on which these forecasts are based and attempts to augment it with the addition of other patterns of climate variability. Two atmospheric teleconnection patterns, the North Atlantic Oscillation and Pacific–North American pattern, are examined as potential indicators of seasonal and monthly area burned in Florida. Although ENSO was the only climate index to show a significant correlation to area burned in Florida, the Pacific–North American pattern (PNA) is shown to be a factor influencing fire season severity although the relationship is not monotonic and therefore not revealed by correlation analysis.

Forecasting intentional wildfires using temporal and spatiotemporal autocorrelations

We report daily time series models containing both temporal and spatiotemporal lags, which are applied to forecasting intentional wildfires in Galicia, Spain. Models are estimated independently for each of the 19 forest districts in Galicia using a 1999-2003 training dataset and evaluated out-of-sample with a 2004-06 dataset. Poisson autoregressive models of order P - PAR(P) models - significantly out-perform competing alternative models over both in-sample and out-of-sample datasets, reducing out-of-sample root-mean-squared errors by an average of 15%. PAR(P) and static Poisson models included covariates deriving from crime theory, including the temporal and spatiotemporal autoregressive time series components. Estimates indicate highly significant autoregressive components, lasting up to 3 days, and spatiotemporal autoregression, lasting up to 2 days. Models also applied to predict the effect of increased arrest rates for illegal intentional firesetting indicate that the direct long-run effect of an additional firesetting arrest, summed across forest districts in Galicia, is -139.6 intentional wildfires, equivalent to a long-run elasticity of -0.94. Language: en

Synthesis of Knowledge of Extreme Fire Behavior: Volume I for Fire Managers

The National Wildfire Coordinating Group definition of extreme fire behavior (EFB) indicates a level of fire behavior characteristics that ordinarily precludes methods of direct control action. One or more of the following is usually involved: high rate of spread, prolific crowning/spotting, presence of fire whirls, and strong convection column. Predictability is difficult because such fires often exercise some degree of influence on their environment and behave erratically, sometimes dangerously. Alternate terms include “blow up” and “fire storm.” Fire managers examining fires over the last 100 years have come to understand many of the factors necessary for EFB development. This work produced guidelines included in current firefighter training, which presents the current methods of predicting EFB by using the crown fire model, which is based on the environmental influences of weather, fuels, and topography. Current training does not include the full extent of scientific understanding. Material in current training programs is also not the most recent scientific knowledge. National Fire Plan funds have sponsored newer research related to wind profiles’ influence on fire behavior, plume growth, crown fires, fire dynamics in live fuels, and conditions associated with vortex development. Of significant concern is that characteristic features of EFB depend on conditions undetectable on the ground, relying fundamentally on invisible properties such as wind shear or atmospheric stability.Obviously no one completely understands all the factors contributing to EFB because of gaps in our knowledge. These gaps, as well as the limitations as to when various models or indices apply should be noted to avoid application where they are not appropriate or warranted. This synthesis will serve as a summary of existing extreme fire behavior knowledge for use by fire managers, firefighters, and fire researchers.The objective of this project is to synthesize existing EFB knowledge in a way that connects the weather, fuel, and topographic factors that contribute to development of EFB. This synthesis will focus on the state of the science, but will also consider how that science is currently presented to the fire management community, including incident commanders, fire behavior analysts, incident meteorologists, National Weather Service office forecasters, and firefighters. It will seek to clearly delineate the known, the unknown, and areas of research with the greatest potential impact on firefighter protection.

Important parameters for smoke plume rise simulation with Daysmoke

Daysmoke is a local smoke transport model and has been used to provide smoke plume rise information. It includes a large number of parameters describing the dynamic and stochastic processes of particle upward movement, fallout, fluctuation, and burn emissions. This study identifies the important parameters for Daysmoke simulations of plume rise and seeks to understand their impacts on regional air quality simulations with the Community Multiscale Air Quality (CMAQ) model. The Fourier Amplitude Sensitivity Test (FAST) was first applied to Daysmoke simulations of prescribed burning in the southeastern U.S. It is shown that, for the specified value ranges of 15 parameters, entrainment coefficient and number of updraft cores are the most important for determining smoke plume rise. Initial plume temperature anomaly, diameter of flaming area, and thermal stability also contribute to a certain extent. CMAQ simulations were then conducted for a couple of different updraft core numbers. The simulated ground PM2.5 concentration is much closer to the measurements with multiple updraft cores than single core. The results from this study therefore suggest that simulations of Daysmoke and CMAQ could be improved by a better understanding of plume structure to aid in specifying the number of smoke updraft cores.

Wildfire potential evaluation during a drought event with a regional climate model and NDVI

Abstract Regional climate modeling is a technique for simulating high-resolution physical processes in the atmosphere, soil and vegetation. It can be used to evaluate wildfire potential by either providing meteorological conditions for computation of fire indices or predicting soil moisture as a direct measure of fire potential. This study examines these roles using a regional climate model (RCM) for the drought and wildfire events in 1988 in the northern United States. The National Center for Atmospheric Research regional climate model (RegCM) was used to conduct simulations of a summer month in each year from 1988 to 1995. The simulated precipitation and maximum surface air temperature were used to calculate the Keetch–Byram Drought Index (KBDI), which is a popular fire potential index. We found that the KBDI increased significantly under the simulated drought condition. The corresponding fire potential was upgraded from moderate for a normal year to high level for the drought year. High fire potential is often an indicator for occurrence of intense and extensive wildfires. Fire potential changed in the opposite direction for the 1993 flood event, indicating little possibility of severe wildfires. The soil moisture and KBDI evaluations under the drought and flood conditions are in agreement with satellite remotely sensed vegetation conditions and the actual wildfire activity. The precipitation anomaly was a more important contributor to the KBDI changes than temperature anomaly. The small magnitude of the simulated soil moisture anomalies during the drought event did not provide sufficient evidence for the role of simulated soil moisture as a direct measure of wildfire potential.