Properties and Radar Cross-Section of forest fire ash particles at millimeter wave

Ghorbani, Kamran; Baum, Thomas C.; Thompson, Lachlan

doi:10.23919/eumc.2012.6459098

Cited by 7 publications

(11 citation statements)

References 10 publications

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“…Baum, Thomson, et al (2011) As per Baum, Thompson, et al (2011), experimenting with different heat exposures Built on Baum, Thompson, et al (2011) with the addition of combining ash at different temperature and ash-to-air volume fraction across samples. Ghorbani et al (2012) Ash of Messmate Stringybark (Eucalyptus obliqua).…”

Section: Complex Dielectrics and Models Of Reflectivitymentioning

confidence: 99%

Wildfire and Weather Radar: A Review

et al. 2019

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Research in the pursuit of better understanding of fire behavior and fire‐atmosphere interaction has frequently encountered a dearth of observational data, especially from events that cause most impact. Here we show that meteorological radar has been demonstrated as an effective tool for profiling the microphysics, thermodynamics, and fire behavior feedback of wildfire plumes, including for cases with deep and moist convection occurring in the fire plume. A synthesis of knowledge on the use of radar for the analysis of wildfire is presented, and the new term pyrometeor is introduced to describe the range of scatterers observed by radar, the reflectivity signature of which is determined by interacting processes of wildfire behavior and atmospheric convection. The reflectivity theories of pyrometeors are compared, and it is shown that there are gaps in knowledge on the size distributions of pyrometeors as well as the complex dielectrics. Observational case studies are compared across plume microphysics, plume thermodynamics and deep pyroconvection, and operational usage of radar to monitor wildfire. The dominant hypothesis of reflectivity is scattering from ash particles, though theories for scattering such as from larger debris exist, although evidence is limited for any hypothesis. Vortices have also been identified using Doppler velocity radar data, but there is limited understanding of their cause and influence on fire‐atmosphere interactions. Recommendations are provided for methods and data sets to advance the application of radar for observing and understanding wildfires, including for plume microphysics and atmosphere‐fire interactions.

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Section: Complex Dielectrics and Models Of Reflectivitymentioning

confidence: 99%

Wildfire and Weather Radar: A Review

et al. 2019

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“…Combining this link between exposed temperature and effective complex permittivity, the image processing method outlined in [28] can be used to approximate the exposed temperature distribution. To achieve this, color-matching techniques were implemented where the average pixel value of each ash particle can be matched to a predefined color model.…”

Section: Exposed Temperature Distributionmentioning

confidence: 99%

“…Similarity in the depolarization factor suggests that the constituents of the cell structures making up powdered ash, regardless of species, respond almost identically to a propagating electromagnetic field. Further analysis on controlled eucalypt specimens exposed to precise temperature ranges of up to 450 • C has shown significant reductions in the complex permittivity and loss tangent with increased temperature [27], [28].…”

Section: Introductionmentioning

confidence: 99%

The Nature of Fire Ash Particles: Microwave Material Properties, Dynamic Behavior, and Temperature Correlation

Baum

Thompson

Ghorbani

2015

IEEE J. Sel. Top. Appl. Earth Observations Remote Sensing

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This paper focuses on the investigation of a number of physical and electromagnetic properties of fire generated ash particles, with relation to radar observations of forest fire smoke columns. Emphasis is placed on understanding the physical properties of the ash, which have direct effects on their scattering ability. Coupled with the electromagnetic properties, these physical properties describe the scatter generated when a number of dispersed ash particles are volumetrically interacting with radar signals. Due to their planar geometry, a study of ash particles originating from the eucalyptus genus has been conducted. Particular focus is placed on this genus due to its high population and role in fueling large bushfires within the Australian continent. The fundamental scattering mechanisms required for describing the radar reflectivity in horizontal, vertical, and cross-polarization have been explored by breaking down and analyzing three distinct properties of an individual ash particle. These include its geometric, dynamic, and electromagnetic properties. Statistical distributions from all three areas have been included to aid in the development of modeling tools.

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“…In one case, they estimated the complex dielectric constant of eucalypt ash to be (6.30 + 0.06j) for a volumetric fraction of 0.5 %. In another study, eucalypt ash particles were measered to have an effective dielectric constant above 2 for ash particles [23]. In the same study, the equivalent RCS of a 55 mm × 55 mm × 55 mm volume containing a 6 × 10 −6 % volume density of ash particles was estimated to be above −100 dB m 2 at X-band (10 GHz).…”

Section: Bushfire Detection and Characterization A Backgroundmentioning

confidence: 99%

Weather and bushfire observation using low cost X-band phased array radars

Palumbo

Al-Ashwal

Ferguson

et al. 2013

2013 International Conference on Radar

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Small-scale, low-cost X-band radars are an emerging technology that offer signficant advantages over traditional largescale systems for weather and remote sensing applications. Xband radars provide enhanced angular resolution at a fraction of the aperture size compared to larger, lower frequency systems. Because of their low cost and small form factor, these radars can now be integrated into more research and commercial applications. This paper presents the research activities currently underway using a low-cost, X-band (9.41 GHz) Phase-Tilt Radar. The "phase-tilt" design is a novel architecture that allows for rapid electronic scanning in azimuth and mechanical tilting in elevation, as a compromise between cost and performance. This paper presents the relevant background information on the technology, as well as some initial studies and field work on the research activities performed.

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Properties and Radar Cross-Section of forest fire ash particles at millimeter wave

Cited by 7 publications

References 10 publications

Wildfire and Weather Radar: A Review

Wildfire and Weather Radar: A Review

The Nature of Fire Ash Particles: Microwave Material Properties, Dynamic Behavior, and Temperature Correlation

Weather and bushfire observation using low cost X-band phased array radars

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