Smoke Observations on a 10-cm Radar 1,2

Hiser, H. W.

doi:10.1175/1520-0477-42.9.621

Cited by 6 publications

(9 citation statements)

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“…Since this time, there has been a small number of observations made using pulsed weather radars over UHF (914 MHz), L (1-2.6 GHz), S (2.6-3.95 GHz), C (3.95-8.2 GHz), X (8. , and W-bands (75-110 GHz) [2]- [15]. In addition, lidar has been studied and compared to radar, with the latter displaying comparable performance [5], [12].…”

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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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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“…Considering typical fire seasons in many countries the curing of biomass in hot weather results in a case were significantly large amounts of hydration are unlikely however not implausible. Precipitation however has not been reported to be occurring within many observations [1][2][3][4][5][6]13]. If ash is unlikely to provide these high epsilon values other significant scattering sources must be present within smoke plumes.…”

Section: Discussionmentioning

confidence: 99%

“…examples include v = 1 (Maxwell-Garnett), v = 2 (Bruggeman) and v = 3 (Coherent Potential). The unified mixing law is given by (1) where the complex permittivity can be broken down into its real and imaginary components (see (2)). …”

Section: B Unified Mixing Lawmentioning

confidence: 99%

“…Since this time, there has been a small number of observations made using pulsed weather radars over UHF, L, C, S, X, and W-Bands [2][3][4][5][6][7][8][9][10][11][12][13][14][15]. Investigations into other active electromagnetic sensor have also been studied and compared to radar with comparable performance [5,12].…”

Section: Introductionmentioning

confidence: 99%

“…Speculated scattering sources from fire include: scattering from ash particles (incoherent/coherent scatter) [2][3][4][5][6][7][10][11][12], clear-air/Bragg scatter [7,17], condensing water vapor [7] and weak ionized alkalis [18,19]. The scattering sources described in literature are all plausible, however; they may not be present within all regions of a smoke column at the same time.…”

Section: Introductionmentioning

confidence: 99%

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Reflectivity modeling of eucalypt ash particles with respects to moisture absorption over microwave and millimeter wave

Baum

Thompson

Ghorbani

2014

2014 11th European Radar Conference

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This paper investigates modeled reflectivity of eucalypt ash particles based on empirically measured geometric, dynamic and complex permittivity models. The eucalypt species is the most common tree genus throughout Australasia. The investigation of ash created from its foliage during bushfires is required to better understand how these particles play a role in the overall reflectivity of smoke plumes. Large smoke plumes are commonly observable on many meteorological radars. Unlike liquid precipitation which displays more homogenous like properties as effective bulk material, ash is significantly more complex. On the particle level the complex permittivity varies over the entire structure, the geometric properties are vastly complex and the internal porosity varies based on the originating cell structures. Taking these complexities in to consideration, modeled reflectivity based on statistically correct particles has been carried out in a full electromagnetic solver driven by an external software framework. The results have been analyzed and discussed.

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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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Smoke Observations on a 10-cm Radar 1,2

Cited by 6 publications

References 0 publications

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

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

Reflectivity modeling of eucalypt ash particles with respects to moisture absorption over microwave and millimeter wave

Wildfire and Weather Radar: A Review

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