A multifrequency laboratory investigation of attenuation and scattering from volcanic ash clouds

Bredow, J.W.; Porco, R.L.; Dawson, M.S.; Betty, C.L.; Self, Stephen; Thordarson, T.

doi:10.1109/36.406693

Cited by 8 publications

(6 citation statements)

References 20 publications

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“…We assumed spherical particles, with log-normal size distributions, and a refractive index of 2.5 + 0.4i. These are educated guesses, based on available literature, for example Manabe et al (1992) and Bredow et al (1995).…”

Section: Observation Techniquementioning

confidence: 99%

Observing ice clouds in the submillimeter spectral range: the CloudIce mission proposal for ESA's Earth Explorer 8

et al. 2012

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Abstract. Passive submillimeter-wave sensors are a way to obtain urgently needed global data on ice clouds, particularly on the so far poorly characterized "essential climate variable" ice water path (IWP) and on ice particle size. CloudIce was a mission proposal to the European Space Agency ESA in response to the call for Earth Explorer 8 (EE8), which ran in 2009/2010. It proposed a passive submillimeter-wave sensor with channels ranging from 183 GHz to 664 GHz. The article describes the CloudIce mission proposal, with particular emphasis on describing the algorithms for the data-analysis of submillimeter-wave cloud ice data (retrieval algorithms) and demonstrating their maturity. It is shown that we have a robust understanding of the radiative properties of cloud ice in the millimeter/submillimeter spectral range, and that we have a proven toolbox of retrieval algorithms to work with these data. Although the mission was not selected for EE8, the concept will be useful as a reference for other future mission proposals.

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Section: Observation Techniquementioning

confidence: 99%

Observing ice clouds in the submillimeter spectral range: the CloudIce mission proposal for ESA's Earth Explorer 8

et al. 2012

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“…The larger particles scatter much more strongly (σ/πr 2 ∝ (kr) 4 , σ denotes radar cross section) than smaller particles. 9) The S11 at the distance 1.44 meters is -45 dB. The attenuation of solid bulk coke, which is caused by dust, is less than 1 dB.…”

Section: Influence Of Particle Size On Propagationmentioning

confidence: 96%

“…6 seem to correspond to volcanic ash results. 9) This is partly because the concentration has impact on dielectric constant. For gas flow prediction the dielectric constant of BF dust is assumed to be constant.…”

Section: Influence Of Dust Concentration On Propagationmentioning

confidence: 99%

Blast Furnace Gas Flow Strength Prediction Using FMCW Radar

Wei

Chen

2015

ISIJ Int.

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A method of predicting gas flow strength upon burden surface has been proposed in this paper. A frequency modulated continuous wave (FMCW) radar is employed to achieve the echo signal of burden surface. The radar, operating at 24-26 GHz, is mounted on top of blast furnace (BF). The burden surface scattering yields attenuation due to the burden surface dust. The propagation constant has been derived in terms of gas flow velocity, particle size, dust concentration and so on. The method has been validated in real blast furnace during production process and maintenance process, respectively. The experiment results show that the predicted value has close agreement with the measured value. The attenuation has the same periodic trend with the BF charging process.

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“…In that paper, the complex refractive index of 2.288+0.0568i is based on the average value found for a number of dry dust particles. In the frequency range 10.0–18.0 GHz, Bredow et al [1995] estimated the complex refractive index of volcanic basaltic ash particles to be about 2.34+0.2i. In this paper, it is assumed that the complex refractive index found for mineral dust and basaltic ash particles at low microwave frequencies is valid at the ISMAR frequencies.…”

Section: Assumptions and Bulk Scattering Propertiesmentioning

confidence: 99%

“…The scarcity of such studies is probably due to the lack of knowledge regarding the dielectric properties of various aerosol materials at microwave frequencies. The dielectric properties of volcanic ash particles have only been reported for frequencies between 4 to 19 GHz [ Adams et al , 1996], for basaltic ash particles in the region 10.0–18.0 GHz by Bredow et al [1995], and for mineral dust aerosol particles in the X‐band region (8.0–12.0 GHz) by Ghobrial and Sharief [1987]. Other reasons why there have been so few studies at higher microwave frequencies could be due to the lack of knowledge concerning particle geometric shape and the shape of the particle size distribution function (PSD).…”

Section: Introductionmentioning

confidence: 99%

A new application of a multifrequency submillimeter radiometer in determining the microphysical and macrophysical properties of volcanic plumes: A sensitivity study

Baran

2012

J. Geophys. Res.

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[1] In this paper, the potential of a multifrequency submillimeter radiometer to characterize ash plumes in the near-field of a volcanic eruption is evaluated. The radiometer's sensitivity to mass concentration and particle effective dimension is shown to depend most critically on aerosol altitude and ejected water vapor concentration. There is also some dependence on temperature, aerosol shape and complex refractive index. For this study, the volcanic aerosols are assumed to be randomly oriented solid hexagonal silicates of aspect ratio unity. The T-matrix method is used to calculate the single-scattering properties of the aerosols at 36 frequencies between 90 GHz and 880 GHz, and the aerosol bulk scattering properties are derived assuming lognormal size distribution functions. A midlatitude standard summer atmosphere and a perturbed midlatitude summer atmosphere are used to quantify the sensitivity, using the delta-Eddington two-stream approximation, of the radiometer to the presence of aerosol. It is shown that at 34 frequencies, between 113 GHz and 880 GHz, the sensitivity to aerosol is a maximum if the following four conditions are satisfied: (i) The altitude of the aerosol layer should be ≫ 3 km, (ii) 0.1 g m À3 < mass concentration < 30 g m À3 (iii) the aerosol effective dimension, D e , 20 mm < D e < 1000 mm and (iv) water vapor ejected by a volcano into the atmosphere should be < 1000 times greater than the background water vapor concentration. The paper demonstrates the potential usefulness of using spectrally resolved submillimeter measurements in the near-field of volcanic eruptions to characterize plume properties.Citation: Baran, A. J. (2012), A new application of a multifrequency submillimeter radiometer in determining the microphysical and macrophysical properties of volcanic plumes: A sensitivity study,

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A multifrequency laboratory investigation of attenuation and scattering from volcanic ash clouds

Cited by 8 publications

References 20 publications

Observing ice clouds in the submillimeter spectral range: the CloudIce mission proposal for ESA's Earth Explorer 8

Observing ice clouds in the submillimeter spectral range: the CloudIce mission proposal for ESA's Earth Explorer 8

Blast Furnace Gas Flow Strength Prediction Using FMCW Radar

A new application of a multifrequency submillimeter radiometer in determining the microphysical and macrophysical properties of volcanic plumes: A sensitivity study

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