The Scattering of Polarized Light by Polydisperse Systems of Irregular Particles

Holland, A. C.; Gagne, G.

doi:10.1364/ao.9.001113

Cited by 207 publications

(57 citation statements)

References 5 publications

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“…This is probably due to the irregularity of the aerosol samples. This finding is supported by several other measured scattering matrices or matrix elements of similar irregular mineral aerosol samples reported in the literature [see Holland and Gagne, 1970 used this and other measured matrices in a study of parameterized scattering matrices to choose a particular parameterization. Such parameterized scattering matrices can be used in analyses of polarization measurements of planets where reliable a priori assumptions on particle shapes or sizes cannot be made.…”

Section: Aerosol Measurementssupporting

confidence: 82%

Scattering matrices of mineral aerosol particles at 441.6 nm and 632.8 nm

Volten¹,

Muñoz²,

Rol³

et al. 2001

J. Geophys. Res.

407

338

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Abstract. We present measured scattering matrices as functions of the scattering angle in the range 5ø-173 ø and at wavelengths of 441.6 nra and 632.8 nra for seven distinct irregularly shaped mineral aerosol samples with properties representative of mineral aerosols present in the Earth's atmosphere. The aerosol samples, i.e., feldspar, red clay, quartz, loess, Pinatubo and Lokon volcanic ash, and Sahara sand, represent a wide variety of particle size (typical diameters between 0.1 and 100 pra) and composition (mainly silicates). We investigate the effects of differences in size and complex refractive index on the light-scattering properties of these irregular particles. In particular, we find that the measured scattering matrix elements when plotted as functions of the scattering angle are confined to rather limited domains. This similarity in scattering behavior justifies the construction of an average aerosol scattering matrix as a function of scattering angle to facilitate, for example, the use of our results for the interpretation of remote sensing data. We show that results of ray-optics calculations, using Gaussian random shapes, are able to describe the experimental data well when taking into account the high irregularity in shape of the aerosols, even when these aerosols are rather small. Using the results of ray-optics calculations, we interpret the differences found between the measured aerosol scattering matrices in terms of differences in complex refractive index and particle size relative to the wavelength. The importance of our results for studies of astronomical objects, such as planets, comets, asteroids, and circumstellar dust shells is discussed.

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Section: Aerosol Measurementssupporting

confidence: 82%

Scattering matrices of mineral aerosol particles at 441.6 nm and 632.8 nm

Volten¹,

Muñoz²,

Rol³

et al. 2001

J. Geophys. Res.

407

338

View full text Add to dashboard Cite

show abstract

“…While these devices are reliable and robust, the measurements over large portions of the phase function do not provide much information about particle morphology due to the lack of angular specificity. Second, some studies use moveable detectors along a ring structure such that the phase function can be measured by sweeping the detector (or multiple detectors) across a broad range of angles (Holland and Gagne, 1970;Hovenier et al, 2003;Jaggard et al, 1981;Kuik et al, 1991;Perry et al, 1978;Volten et al, 2001). While this allows for good angular coverage (up to 3-173 • ; Hovenier et al, 2003), the method is generally bulky, must be mechanically stable, and requires a constant population of aerosol particles that does not change appreciably during the detector sweep.…”

Section: Introductionmentioning

confidence: 99%

Investigating biomass burning aerosol morphology using a laser imaging nephelometer

et al. 2018

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Abstract. Particle morphology is an important parameter affecting aerosol optical properties that are relevant to climate and air quality, yet it is poorly constrained due to sparse in situ measurements. Biomass burning is a large source of aerosol that generates particles with different morphologies. Quantifying the optical contributions of non-spherical aerosol populations is critical for accurate radiative transfer models, and for correctly interpreting remote sensing data. We deployed a laser imaging nephelometer at the Missoula Fire Sciences Laboratory to sample biomass burning aerosol from controlled fires during the FIREX intensive laboratory study. The laser imaging nephelometer measures the unpolarized scattering phase function of an aerosol ensemble using diode lasers at 375 and 405 nm. Scattered light from the bulk aerosol in the instrument is imaged onto a chargecoupled device (CCD) using a wide-angle field-of-view lens, which allows for measurements at 4-175 • scattering angle with ∼ 0.5 • angular resolution. Along with a suite of other instruments, the laser imaging nephelometer sampled fresh smoke emissions both directly and after removal of volatile components with a thermodenuder at 250 • C. The total integrated aerosol scattering signal agreed with both a cavity ring-down photoacoustic spectrometer system and a traditional integrating nephelometer within instrumental uncertainties. We compare the measured scattering phase functions at 405 nm to theoretical models for spherical (Mie) and fractal (Rayleigh-Debye-Gans) particle morphologies based on the size distribution reported by an optical particle counter.Results from representative fires demonstrate that particle morphology can vary dramatically for different fuel types. In some cases, the measured phase function cannot be described using Mie theory. This study demonstrates the capabilities of the laser imaging nephelometer instrument to provide realtime, in situ information about dominant particle morphology, which is vital for understanding remote sensing data and accurately describing the aerosol population in radiative transfer calculations.

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“…Especially there are no investigations of the phase function of yellow sand particles in the North-Eastern Asia to our knowledge . The scattering property of each nonspherical particle depends on its shape as shown by a number of measurements of light scattering by nonspherical particles in laboratory conditions (e.g., Holland and Gagne, 1970;Pinnick et al, 1976;Chylek et al, 1977;Zerull, 1976;Schuerman et al, 1981;Coletti, 1984). For example, the asymmetry factor can increase or decrease as compared with the equalvolume sphere, depending on the particle shape and size (Mugnai and Wiscombe, 1986).…”

Section: Introductionmentioning

confidence: 99%

Aerosol Optical Characteristics in the Yellow Sand Events Observed in May, 1982 at Nagasaki-Part II Models

Nakajima

Tanaka

Yamano

et al. 1989

Journal of the Meteorological Society of Japan

168

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Phase functions of yellow sand particles were measured by a polar nephelometer during 24 April-11 May, 1982 at Nagasaki, Japan. They suggested a strong nonsphericity of the particles, which can be reconstructed by the semi-empirical theory of Pollack and Cuzzi or by Mie particles with large fictitious absorption. Spectral extinction cross section, single scattering albedo, asymmetry factor and backscattering phase function were estimated using the volume spectra retrieved from data of several instruments including the polar nephelometer data. Volume loading of yellow sand particles at the observation site was estimated as 666l/km2 at the maximum stage of the yellow sand event of 4-6 May and 183l/km2 for the secondary maximum of 8 May. Using two estimates of the absorption index (0.01 and a model variable with wavelengths), these values show that solar radiative heating from 0.08 to 0.4*/day can be expected in the atmosphere over considerably wide area in one yellow sand event.

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The Scattering of Polarized Light by Polydisperse Systems of Irregular Particles

Cited by 207 publications

References 5 publications

Scattering matrices of mineral aerosol particles at 441.6 nm and 632.8 nm

Scattering matrices of mineral aerosol particles at 441.6 nm and 632.8 nm

Investigating biomass burning aerosol morphology using a laser imaging nephelometer

Aerosol Optical Characteristics in the Yellow Sand Events Observed in May, 1982 at Nagasaki-Part II Models

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