Radiant flux density, energy density and fuel consumption in mixed-oak forest surface fires

2012 ◽  
Vol 21 (6) ◽  
pp. 722 ◽  
Author(s):  
R. L. Kremens ◽  
M. B. Dickinson ◽  
A. S. Bova
Keyword(s):  
Energy Density ◽  
Fuel Consumption ◽  
Energy Transport ◽  
Heat Budget ◽  
Wildland Fire ◽  
Linear Increase ◽  
Dual Band ◽  
Radiative Energy ◽  
Eastern United States ◽  
Soil Heating

Closing the wildland fire heat budget involves characterising the heat source and energy dissipation across the range of variability in fuels and fire behaviour. Meeting this challenge will lay the foundation for predicting direct ecological effects of fires and fire–atmosphere coupling. In this paper, we focus on the relationships between the fire radiation field, as measured from the zenith, fuel consumption and the behaviour of spreading flame fronts. Experiments were conducted in 8 × 8-m outdoor plots using preconditioned wildland fuels characteristic of mixed-oak forests of the eastern United States. Using dual-band radiometers with a field of view of ~18.5 m2 at a height of 4.2 m, we found a near-linear increase in fire radiative energy density over a range of fuel consumption between 0.15 and 3.25 kg m–2. Using an integrated heat budget, we estimate that the fraction of total theoretical combustion energy density radiated from the plot averaged 0.17, the fraction of latent energy transported in the plume averaged 0.08, and the fraction accounted for by the combination of fire convective energy transport and soil heating averaged 0.72. Future work will require, at minimum, instantaneous and time-integrated estimates of energy transported by radiation, convection and soil heating across a range of fuels.

Measurements relating fire radiative energy density and surface fuel consumption – RxCADRE 2011 and 2012

2016 ◽  
Vol 25 (1) ◽  
pp. 25 ◽  
Author(s):  
Andrew T. Hudak ◽  
Matthew B. Dickinson ◽  
Benjamin C. Bright ◽  
Robert L. Kremens ◽  
E. Louise Loudermilk ◽  
...  
Keyword(s):  
Energy Density ◽  
Fuel Consumption ◽  
Airborne Lidar ◽  
Radiative Energy ◽  
Small Scale ◽  
Power Flux ◽  
Fuel Loads ◽  
Fire Modelling ◽  
Before And After ◽  
Radiometric Signal

Small-scale experiments have demonstrated that fire radiative energy is linearly related to fuel combusted but such a relationship has not been shown at the landscape level of prescribed fires. This paper presents field and remotely sensed measures of pre-fire fuel loads, consumption, fire radiative energy density (FRED) and fire radiative power flux density (FRFD), from which FRED is integrated, across forested and non-forested RxCADRE 2011 and 2012 burn blocks. Airborne longwave infrared (LWIR) image time series were calibrated to FRFD and integrated to provide FRED. Surface fuel loads measured in clip sample plots were predicted across burn blocks from airborne lidar-derived metrics. Maps of surface fuels and FRED were corrected for occlusion of the radiometric signal by the overstorey canopy in the forested blocks, and FRED maps were further corrected for temporal and spatial undersampling of FRFD. Fuel consumption predicted from FRED derived from both airborne LWIR imagery and various ground validation sensors approached a linear relationship with observed fuel consumption, which matched our expectation. These field, airborne lidar and LWIR image datasets, both before and after calibrations and corrections have been applied, will be made publicly available from a permanent archive for further analysis and to facilitate fire modelling.

Observations of energy transport and rate of spreads from low-intensity fires in longleaf pine habitat – RxCADRE 2012

2016 ◽  
Vol 25 (1) ◽  
pp. 76 ◽  
Author(s):  
B. Butler ◽  
C. Teske ◽  
D. Jimenez ◽  
J. O'Brien ◽  
P. Sopko ◽  
...  
Keyword(s):  
Total Energy ◽  
Energy Transport ◽  
Wildland Fire ◽  
Ground Level ◽  
Radiative Energy ◽  
Convective Heating ◽  
Emissive Power ◽  
Rate Of Spread ◽  
Heating And Cooling ◽  
Air Temperatures

Wildland fire rate of spread (ROS) and intensity are determined by the mode and magnitude of energy transport from the flames to the unburned fuels. Measurements of radiant and convective heating and cooling from experimental fires are reported here. Sensors were located nominally 0.5 m above ground level. Flame heights varied from 0.3 to 1.8 m and flaming zone depth varied from 0.3 to 3.0 m. Fire ROS derived from observations of fire transit time between sensors was 0.10 to 0.48 m s–1. ROS derived from ocular estimates reached 0.51 m s–1 for heading fire and 0.25 m s–1 for backing fire. Measurements of peak radiant and total energy incident on the sensors during flame presence reached 18.8 and 36.7 kW m–2 respectively. Peak air temperatures reached 1159°C. Calculated fire radiative energy varied from 7 to 162 kJ m–2 and fire total energy varied from 3 to 261 kJ m–2. Measurements of flame emissive power peaked at 95 kW m–2. Average horizontal air flow in the direction of flame spread immediately before, during, and shortly after the flame arrival reached 8.8 m s–1, with reverse drafts of 1.5 m s–1; vertical velocities varied from 9.9 m s–1 upward flow to 4.5 m s–1 downward flow. The observations from these fires contribute to the overall understanding of energy transport in wildland fires.

Evaluation of the CONSUME and FOFEM fuel consumption models in pine and mixed hardwood forests of the eastern United States

2014 ◽  
Vol 44 (7) ◽  
pp. 784-795 ◽  
Author(s):  
Susan J. Prichard ◽  
Eva C. Karau ◽  
Roger D. Ottmar ◽  
Maureen C. Kennedy ◽  
James B. Cronan ◽  
...  
Keyword(s):  
United States ◽  
Fuel Consumption ◽  
Prescribed Burning ◽  
Forest Type ◽  
Fire Effects ◽  
Eastern United States ◽  
Validation Data ◽  
Data Set ◽  
Predicted Values ◽  
Fine Fuels

Reliable predictions of fuel consumption are critical in the eastern United States (US), where prescribed burning is frequently applied to forests and air quality is of increasing concern. CONSUME and the First Order Fire Effects Model (FOFEM), predictive models developed to estimate fuel consumption and emissions from wildland fires, have not been systematically evaluated for application in the eastern US using the same validation data set. In this study, we compiled a fuel consumption data set from 54 operational prescribed fires (43 pine and 11 mixed hardwood sites) to assess each model’s uncertainties and application limits. Regions of indifference between measured and predicted values by fuel category and forest type represent the potential error that modelers could incur in estimating fuel consumption by category. Overall, FOFEM predictions have narrower regions of indifference than CONSUME and suggest better correspondence between measured and predicted consumption. However, both models offer reliable predictions of live fuel (shrubs and herbaceous vegetation) and 1 h fine fuels. Results suggest that CONSUME and FOFEM can be improved in their predictive capability for woody fuel, litter, and duff consumption for eastern US forests. Because of their high biomass and potential smoke management problems, refining estimates of litter and duff consumption is of particular importance.

Radiative Energy Transport

2021 ◽  
pp. 73-83
Author(s):  
Tianshu Liu ◽  
John P. Sullivan ◽  
Keisuke Asai ◽  
Christian Klein ◽  
Yasuhiro Egami
Keyword(s):  
Energy Transport ◽  
Radiative Energy ◽  
Radiative Energy Transport

Buoyancy-driven flows of a radiatively participating fluid in a vertical cylinder heated from below

1993 ◽  
Vol 442 (1915) ◽  
pp. 313-341 ◽  
Keyword(s):  
Rayleigh Number ◽  
Energy Transport ◽  
Vertical Cylinder ◽  
Side Wall ◽  
Radiative Energy ◽  
Parameter Study ◽  
Internal Radiation ◽  
Static State ◽  
Buoyancy Driven Flows ◽  
Radiative Energy Transport

The effect of radiative energy transport on the onset and evolution of natural convective flows is studied in a Rayleigh–Bénard system. Steady, axisymmetric flows of a radiatively participating fluid contained in a rigid-walled, vertical cylinder which is heated on the base, cooled on top, and insulated on the side wall are calculated by using the Galerkin finite element method. Bifurcation analysis techniques are used to investigate the changes in the flow structure due to internal radiation. The results of this two-parameter study – where the Rayleigh number, Ra and optical thickness, ז , are varied – apply to fluids ranging from opaque to nearly transparent with respect to infrared radiation. For any non-opaque fluid, internal radiation eliminates the static state that, without radiation, exists for all values of the Rayleigh number. This heat transfer mechanism also destroys a symmetry of the system that relates clockwise and counter-clockwise flows. The connectivity between characteristic flow families and the range of Ra where families are stable are found to depend greatly on ז . Results demonstrate the inadequacy of characterizing the behaviour of this system using simple notions of radiative transfer in optically thick or thin media; the nonlinear interaction of radiation and flow are far more complicated than these asymptotic limits would imply.

Measurements, datasets and preliminary results from the RxCADRE project – 2008, 2011 and 2012

2016 ◽  
Vol 25 (1) ◽  
pp. 1 ◽  
Author(s):  
Roger D. Ottmar ◽  
J. Kevin Hiers ◽  
Bret W. Butler ◽  
Craig B. Clements ◽  
Matthew B. Dickinson ◽  
...  
Keyword(s):  
Wildland Fire ◽  
Fire Effects ◽  
Service Research ◽  
Prescribed Fires ◽  
Eastern United States ◽  
Fire Modelling ◽  
The Us ◽  
Us Forest Service ◽  
Research Experiment ◽  
Science Disciplines

The lack of independent, quality-assured field data prevents scientists from effectively evaluating and advancing wildland fire models. To rectify this, scientists and technicians convened in the south-eastern United States in 2008, 2011 and 2012 to collect wildland fire data in six integrated core science disciplines defined by the fire modelling community. These were fuels, meteorology, fire behaviour, energy, smoke emissions and fire effects. The campaign is known as the Prescribed Fire Combustion and Atmospheric Dynamics Research Experiment (RxCADRE) and sampled 14 forest and 14 non-forest sample units associated within 6 small replicate (<10 ha) and 10 large operational (between 10 and 1000 ha) prescribed fires. Precampaign planning included identifying hosting agencies receptive to research and the development of study, logistics and safety plans. Data were quality-assured, reduced, analysed and formatted and placed into a globally accessible repository maintained by the US Forest Service Research Data Archive. The success of the RxCADRE project led to the commencement of a follow-on larger multiagency project called the Fire and Smoke Model Evaluation Experiment (FASMEE). This overview summarises the RxCADRE project and nine companion papers that describe the data collection, analysis and important conclusions from the six science disciplines.

scholarly journals Modeling Regional-Scale Wildland Fire Emissions with the Wildland Fire Emissions Information System*

2014 ◽  
Vol 18 (16) ◽  
pp. 1-26 ◽  
Author(s):  
Nancy H. F. French ◽  
Donald McKenzie ◽  
Tyler Erickson ◽  
Benjamin Koziol ◽  
Michael Billmire ◽  
...  
Keyword(s):  
United States ◽  
Information System ◽  
North America ◽  
Fuel Consumption ◽  
Carbon Emissions ◽  
Wildland Fire ◽  
The United States ◽  
Fire Emissions ◽  
The U.S ◽  
The Web

Abstract As carbon modeling tools become more comprehensive, spatial data are needed to improve quantitative maps of carbon emissions from fire. The Wildland Fire Emissions Information System (WFEIS) provides mapped estimates of carbon emissions from historical forest fires in the United States through a web browser. WFEIS improves access to data and provides a consistent approach to estimating emissions at landscape, regional, and continental scales. The system taps into data and tools developed by the U.S. Forest Service to describe fuels, fuel loadings, and fuel consumption and merges information from the U.S. Geological Survey (USGS) and National Aeronautics and Space Administration on fire location and timing. Currently, WFEIS provides web access to Moderate Resolution Imaging Spectroradiometer (MODIS) burned area for North America and U.S. fire-perimeter maps from the Monitoring Trends in Burn Severity products from the USGS, overlays them on 1-km fuel maps for the United States, and calculates fuel consumption and emissions with an open-source version of the Consume model. Mapped fuel moisture is derived from daily meteorological data from remote automated weather stations. In addition to tabular output results, WFEIS produces multiple vector and raster formats. This paper provides an overview of the WFEIS system, including the web-based system functionality and datasets used for emissions estimates. WFEIS operates on the web and is built using open-source software components that work with open international standards such as keyhole markup language (KML). Examples of emissions outputs from WFEIS are presented showing that the system provides results that vary widely across the many ecosystems of North America and are consistent with previous emissions modeling estimates and products.

scholarly journals Energetic Constraints on the Position of the Intertropical Convergence Zone

2014 ◽  
Vol 27 (13) ◽  
pp. 4937-4951 ◽  
Author(s):  
Tobias Bischoff ◽  
Tapio Schneider
Keyword(s):  
Global Warming ◽  
Energy Input ◽  
Energy Transport ◽  
Intertropical Convergence Zone ◽  
Radiative Energy ◽  
Convergence Zone ◽  
Net Energy ◽  
Lower Boundary Condition ◽  
Near Surface ◽  
Atmospheric Energy

The intertropical convergence zone (ITCZ) can shift meridionally on seasonal and longer time scales. Previous studies have shown that the latitude of the ITCZ is negatively correlated with cross-equatorial atmospheric energy transport. For example, the ITCZ shifts southward as the Northern Hemisphere cools and the northward cross-equatorial energy transport strengthens in response. It has remained unclear what controls the sensitivity of the ITCZ position to cross-equatorial energy transport and what other factors may lead to shifts of the ITCZ position. Here it is shown that the sensitivity of the ITCZ position to cross-equatorial energy transport depends on the net energy input to the equatorial atmosphere: the net radiative energy input minus any energy uptake by the oceans. Changes in this energy input can also lead to ITCZ shifts. The cross-equatorial energy transport is related through a series of approximations to interhemispheric asymmetries in the near-surface temperature distribution. The resulting theory of the ITCZ position is tested in idealized general circulation model simulations with a slab ocean as lower boundary condition. In the simulations, cross-equatorial energy transport increases under global warming (primarily because extratropical latent energy fluxes strengthen), and this shifts the ITCZ poleward. The ITCZ shifts equatorward if primarily the tropics warm in response to an increased net energy input to the equatorial atmosphere. The results have implications for explaining the varied response of the ITCZ to global or primarily tropical changes in the atmospheric energy balance, such as those that occur under global warming or El Niño.

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