The Experts below are selected from a list of 192 Experts worldwide ranked by ideXlab platform
Paul A. Knapp - One of the best experts on this subject based on the ideXlab platform.
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Spatio-temporal patterns of large Grassland Fires in the Intermountain West, U.S.A
Global Ecology and Biogeography, 1998Co-Authors: Paul A. KnappAbstract:The spatial and temporal occurrence of large Grassland Fires (>2008 ha) in the Intermountain West was examined for the period 1980 through 1995. Results suggest that these Fires are largely predictable through space and time. Of the 360 large Fires, 339 occurred within eight regions as defined by clustering of Fires within physiographic boundaries. These regions were characterized by their abundance of exotic annual grasses and flatter terrain that provided continuous fine-fuel conditions that promoted fire spread. Temporally, the likelihood of a large fire is correlated with summer moisture conditions (Z-index values) in the year preceding that of the fire that are either near-normal or wetter. Conversely,
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spatio temporal patterns of large Grassland Fires in the intermountain west u s a
Global Ecology and Biogeography, 1998Co-Authors: Paul A. KnappAbstract:The spatial and temporal occurrence of large Grassland Fires (>2008 ha) in the Intermountain West was examined for the period 1980 through 1995. Results suggest that these Fires are largely predictable through space and time. Of the 360 large Fires, 339 occurred within eight regions as defined by clustering of Fires within physiographic boundaries. These regions were characterized by their abundance of exotic annual grasses and flatter terrain that provided continuous fine-fuel conditions that promoted fire spread. Temporally, the likelihood of a large fire is correlated with summer moisture conditions (Z-index values) in the year preceding that of the fire that are either near-normal or wetter. Conversely, <20% of all the large Fires occurred when the previous summer's Z values were below normal. This may be explained by enhanced fine-fuel build-up enabled by mesic conditions, causing increased biomass in the following summer and thus increasing the incidence of large Fires. Moisture conditions in the summer in which the large Fires occurred appeared to have less influence on the likelihood of those Fires.
Don Latham - One of the best experts on this subject based on the ideXlab platform.
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numerical simulations of Grassland Fires in the northern territory australia a new subgrid scale fire parameterization
Journal of Geophysical Research, 2003Co-Authors: Terry L Clark, Michael J Reeder, Morwenna Griffiths, Don LathamAbstract:[1] A new subgrid-scale parameterization is developed to incorporate the effects of wild Fires into a numerical model of the atmosphere. The parameterization is written in terms of the temperature of the combusting material and the concentration of the unburned airborne fuel. There are two central assumptions on which the parameterization rests. First, the transport of oxygen into the region of combustion, which limits the rate of oxidation, is represented by Rayleigh mixing with a fixed timescale. Second, the combusting gases and the atmosphere are treated as separate fluids. For simplicity, the effects of conduction between the combusting fluid and the atmosphere are purposely not considered in this paper. This means that the grid-scale buoyancy is defined as a volume average of the buoyancy of the combusting fluid and the ambient atmosphere, and that fire-induced buoyancy is confined to the region containing the combusting gases. These assumptions lead to a highly simplified system capturing the essence of the combustion process. The parameterization is used in a simulation of an observed grass fire in the Northern Territory (Australia).
Terry L Clark - One of the best experts on this subject based on the ideXlab platform.
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Infrared observations and numerical modelling of Grassland Fires in the Northern Territory, Australia
Meteorology and Atmospheric Physics, 2005Co-Authors: Terry L Clark, Michael J Reeder, Morwenna Griffiths, David Packham, Noreen KruselAbstract:This paper reports on a small-scale pilot experiment held early in the dry season near Darwin, Australia, in which fine-scale observations of several prescribed Fires were made using infrared digital video. Infrared imaging is used routinely to locate Fires as infrared radiation suffers little attenuation as it propagates through the smoke that normally obscures visible imagery. However, until now, little use has been made of digital video imagery in analyzing the convective-scale structure of prescribed (or wild) Fires. The advantage of digital video imagery is that the individual frames can be objectively analyzed to determine the convective motion in the plane viewed by the camera. The infrared imagery shows mostly rising plumes, much like convective clouds. The flow is highly convective, and the vertical transport of heat is confined to relatively narrow thermals. The updrafts range from a few m s^−1 to around 15 m s^−1. A numerical model is used to simulate one of the prescribed Fires at very high-resolution. For the most part, the model predictions compare well to the observations. The model produces plumes that are around 7 m high, and spaced around 5 m apart, which is similar to that observed. The model correctly predicts the mean rate of spread of the fire to be 1.3 m s^−1. Perhaps the most serious limitations to using infrared observations of the type presented here are the difficulties in interpreting precisely the relationship between the observed infrared temperature field and the air temperature calculated by the model, and the exact connection between the infrared camera derived flow field and that calculated by the model.
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of Grassland Fires in the northern territory australia
2005Co-Authors: Terry L Clark, Michael J Reeder, Morwenna Griffiths, David Packham, Noreen KruselAbstract:Summary This paper reports on a small-scale pilot experiment held early in the dry season near Darwin, Australia, in which fine-scale observations of several prescribed Fires were made using infrared digital video. Infrared imaging is used routinely to locate Fires as infrared radiation suffers little attenuation as it propagates through the smoke that normally obscures visible imagery. However, until now, little use has been made of digital video imagery in analyzing the convective-scale structure of prescribed (or wild) Fires. The advantage of digital video imagery is that the individual frames can be objectively analyzed to determine the convective motion in the plane viewed by the camera. The infrared imagery shows mostly rising plumes, much like convective clouds. The flow is highly convective, and the vertical transport of heat is confined to relatively narrow thermals. The updrafts range from a few ms � 1 to around 15 m s � 1 . A numerical model is used to simulate one of the prescribed Fires at very high-resolution. For the most part, the model predictions compare well to the observations. The model produces plumes that are around 7 m high, and spaced around 5 m apart, which is similar to that observed. The model correctly predicts the mean rate of spread of the fire to be 1.3 m s � 1 . Perhaps the most serious limitations to using infrared observations of the type presented here are the difficulties in interpreting precisely the relationship between the observed infrared temperature field and the air temperature calculated by the model, and the exact connection between the infrared camera derived flow field and that calculated by the model.
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numerical simulations of Grassland Fires in the northern territory australia a new subgrid scale fire parameterization
Journal of Geophysical Research, 2003Co-Authors: Terry L Clark, Michael J Reeder, Morwenna Griffiths, Don LathamAbstract:[1] A new subgrid-scale parameterization is developed to incorporate the effects of wild Fires into a numerical model of the atmosphere. The parameterization is written in terms of the temperature of the combusting material and the concentration of the unburned airborne fuel. There are two central assumptions on which the parameterization rests. First, the transport of oxygen into the region of combustion, which limits the rate of oxidation, is represented by Rayleigh mixing with a fixed timescale. Second, the combusting gases and the atmosphere are treated as separate fluids. For simplicity, the effects of conduction between the combusting fluid and the atmosphere are purposely not considered in this paper. This means that the grid-scale buoyancy is defined as a volume average of the buoyancy of the combusting fluid and the ambient atmosphere, and that fire-induced buoyancy is confined to the region containing the combusting gases. These assumptions lead to a highly simplified system capturing the essence of the combustion process. The parameterization is used in a simulation of an observed grass fire in the Northern Territory (Australia).
Jiquan Zhang - One of the best experts on this subject based on the ideXlab platform.
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risk assessment using transfer learning for Grassland Fires
Agricultural and Forest Meteorology, 2019Co-Authors: Guangquan Zhang, Jie Lu, Jiquan ZhangAbstract:Abstract A new direction of risk assessment research in Grassland fire management is data-driven prediction, in which data are collected from particular regions. Since some regions have rich datasets that can easily generate knowledge for risk prediction, and some have no data available, this study addresses how we can leverage the knowledge learned from one Grassland risk assessment to assist with a current assessment task. In this paper, we first introduce the transfer learning methodology to map and update risk maps in Grassland fire management, and we propose a new Grassland fire risk analysis method. In this study, two major Grassland areas (Xilingol and Hulunbuir) in northern China are selected as the study areas, and five representative indicators (features) are extracted from Grassland fuel, fire climate, accessibility, human and social economy. Taking Xilingol as the source domain (where sufficient labelled data are available) and Hulunbuir as the target domain (which contains insufficient data but requires risk assessment/prediction), we then establish the mapping relationship between Grassland fire indicators and the degrees of Grassland fire risk by using a transfer learning method. Finally, the fire risk in the Hulunbuir Grassland is assessed using the transfer learning method. Experiments show that the prediction accuracy reached 87.5% by using the transfer learning method, representing a significant increase over existing methods.
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Himawari-8 Satellite Based Dynamic Monitoring of Grassland Fire in China-Mongolia Border Regions
Sensors, 2018Co-Authors: Li Na, Jiquan Zhang, Risu Na, Siqin Tong, Alu SiAbstract:In this study, we used bands 7, 4, and 3 of the Advance Himawari Imager (AHI) data, combined with a Threshold Algorithm and a visual interpretation method to monitor the entire process of Grassland Fires that occurred on the China-Mongolia border regions, between 05:40 (UTC) on April 19th to 13:50 (UTC) on April 21st 2016. The results of the AHI data monitoring are evaluated by the fire point product data, the wind field data, and the environmental information data of the area in which the fire took place. The monitoring result shows that, the Grassland fire burned for two days and eight hours with a total burned area of about 2708.29 km2. It mainly spread from the northwest to the southeast, with a maximum burning speed of 20.9 m/s, a minimum speed of 2.52 m/s, and an average speed of about 12.07 m/s. Thus, using AHI data can not only quickly and accurately track the dynamic development of a Grassland fire, but also estimate the spread speed and direction. The evaluation of fire monitoring results reveals that AHI data with high precision and timeliness can be highly consistent with the actual situation.
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Modeling the early warning of Grassland fire risk based on fuzzy logic in Xilingol, Inner Mongolia
Natural Hazards, 2014Co-Authors: Jiquan Zhang, Zhijun TongAbstract:A fuzzy logic-based methodology modeling the early warning of risk to manage Grassland Fires in Inner Mongolia is presented. By establishing a membership function, this study first analyzed Grassland fire hazard and vulnerability and subsequently integrated hazard and vulnerability using the fuzzy logic method to develop the Grassland Fire Risk Early Warning Index. The key parameters in the model were obtained by methods of undetermined parameters. The reliability of early warning results was demonstrated using historical Grassland Fires and Grassland fire disasters. The results from this study are intended to support local, provincial, and national government agencies in making decisions in resource allocation, high-level planning and raising the public’s risk awareness of Grassland Fires.
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Grid based dynamic risk assessment for Grassland fire disaster in Hulunbuir
Stochastic Environmental Research and Risk Assessment, 2014Co-Authors: Qi Zhang, Jiquan Zhang, Zhijun TongAbstract:Grassland fire disaster is one of the most destructive Grassland disasters, which is sudden, destructive, and hard to handle. It caused a great threat to the humanity and property in pastoral. In this study, a dynamic risk assessment model was built based on the data of prairie fire statistics and related meteorological data from 1994 to 2005 in the six livestock counties of Hulunbuir Grassland. Logistic regression model was used in the identification of the key factors influence Grassland fire disaster risk. In the calculation of the weight of individual indicators, analytic hierarchy through scoring by experts was used. Grid GIS technology combined with regression analysis was used in the spatial distribution of indicators which has higher resolution than counties. Assessment factors of endogenous and exogenous sources of warning signs of Grassland Fires were analyzed through weighted comprehensive analysis. Fire disasters from 1994 to 2004 were taken as the sample cases to determine the threshold of risk level by using optimal partition method. Taking the Grassland Fires in 2005 as examples to validate the dynamic risk assessment model, results shown high risk areas coincide well with the distribution of fire points, this proved the accuracy of the model. The dynamic risk assessment results could be used to guide and manage the mitigation of Grassland fire disaster and rescue goods distribution.
Vasyl Yoschenko - One of the best experts on this subject based on the ideXlab platform.
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resuspension and redistribution of radionuclides during Grassland and forest Fires in the chernobyl exclusion zone part ii modeling the transport process
Journal of Environmental Radioactivity, 2006Co-Authors: Vasyl Yoschenko, V A Kashparov, S Levchuk, A S Glukhovskiy, Yu V Khomutinin, V P Protsak, S M Lundin, J TschierschAbstract:Abstract To predict parameters of radionuclide resuspension, transport and deposition during forest and Grassland Fires, several model modules were developed and adapted. Experimental data of controlled burning of prepared experimental plots in the Chernobyl exclusion zone have been used to evaluate the prognostic power of the models. The predicted trajectories and elevations of the plume match with those visually observed during the fire experiments in the Grassland and forest sites. Experimentally determined parameters could be successfully used for the calculation of the initial plume parameters which provide the tools for the description of various fire scenarios and enable prognostic calculations. In summary, the model predicts a release of some ‰ from the radionuclide inventory of the fuel material by the Grassland Fires. During the forest fire, up to 4% of 137 Cs and 90 Sr and up to 1% of the Pu isotopes can be released from the forest litter according to the model calculations. However, these results depend on the parameters of the fire events. In general, the modeling results are in good accordance with the experimental data. Therefore, the considered models were successfully validated and can be recommended for the assessment of the resuspension and redistribution of radionuclides during Grassland and forest Fires in contaminated territories.
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resuspension and redistribution of radionuclides during Grassland and forest Fires in the chernobyl exclusion zone part i fire experiments
Journal of Environmental Radioactivity, 2006Co-Authors: Vasyl Yoschenko, V A Kashparov, S Levchuk, Yu V Khomutinin, V P Protsak, S M Lundin, A M Kadygrib, S I Zvarich, I M Maloshtan, V P LanshinAbstract:Controlled burning of experimental plots of forest or Grassland in the Chernobyl exclusion zone has been carried out in order to estimate the parameters of radionuclide resuspension, transport and deposition during forest and Grassland Fires and to evaluate the working conditions of firemen. An increase of several orders of magnitude of the airborne radionuclide concentration was observed in the territory near the fire area. The resuspension factor for (137)Cs and (90)Sr was determined to range from 10(-6) to 10(-5) m(-1), and for the plutonium radionuclides from 10(-7) to 10(-6) m(-1) (related to the nuclides in the combustible biomass). These values are 2 orders of magnitude lower if they are calculated relatively to the total contamination density (including the nuclides in the soil). The radionuclide fallout along the plume axis is negligible in comparison to the existing contamination. However, the additional inhalation dose for firemen exposed in the affected area can reach the level of the additional external irradiation in the period of their mission. The plutonium nuclides constitute the dominating contribution to the inhalation dose.
