Light scattering from particles of regular and irregular shape

Jaggard, D.L.; Hill, Christopher P.; Shorthill, R. W.; Stuart, Deborah; Glantz, Michael; Rosswog, F.; Taggart, Bill; Hammond, Shaless L.

doi:10.1016/0004-6981(81)90066-4

Cited by 43 publications

(27 citation statements)

References 16 publications

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“…With this limitation, the pragmatic approach has been to vary the shape distribution of these spheroids to best match the observed and computed scattering intensities. The success of this approach can be measured by the fact that predictions of nearly flat phase functions at side scattering angles by size distributions of volume‐equivalent spheroids are borne out in laboratory measurements of natural particles [ Jaggard et al , 1981; Volten et al , 2001], and in the significant improvements between measured and modeled sky radiance when spheroids are used instead of spheres in the case of mineral dust [ Dubovik et al , 2002b]. With these considerations, the agreement between the lidar ratios for mineral dust we predicted using spheroids (i.e., scattering at 180 degrees) and those measured in the field is very encouraging.…”

Section: Discussionmentioning

confidence: 99%

Variability of aerosol and spectral lidar and backscatter and extinction ratios of key aerosol types derived from selected Aerosol Robotic Network locations

et al. 2005

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[1] The lidar (extinction-to-backscatter) ratios at 0.55 and 1.02 mm and the spectral lidar, extinction, and backscatter ratios of climatically relevant aerosol species are computed on the basis of selected retrievals of aerosol properties from 26 Aerosol Robotic Network (AERONET) sites across the globe. The values, obtained indirectly from sky radiance and solar transmittance measurements, agree very well with values from direct observations. Low mean values of the lidar ratio, S a , at 0.55 mm for maritime (27 sr) aerosols and desert dust (42 sr) are clearly distinguishable from biomass burning (60 sr) and urban/industrial pollution (71 sr). The effects of nonsphericity of mineral dust are shown, demonstrating that particle shape must be taken into account in any spaceborne lidar inversion scheme. A new aerosol model representing pollution over Southeast Asia is introduced since lidar (58 sr), color lidar, and extinction ratios in this region are distinct from those over other urban/industrial centers, owing to a greater number of large particles relative to fine particles. This discrimination promises improved estimates of regional climate forcing by aerosols containing black carbon and is expected to be of utility to climate modeling and remote sensing communities. The observed variability of the lidar parameters, combined with current validated aerosol data products from Moderate Resolution Imaging Spectroradiometer (MODIS), will afford improved accuracy in the inversion of spaceborne lidar data over both land and ocean.Citation: Cattrall, C., J. Reagan, K. Thome, and O. Dubovik (2005), Variability of aerosol and spectral lidar and backscatter and extinction ratios of key aerosol types derived from selected Aerosol Robotic Network locations,

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Section: Discussionmentioning

confidence: 99%

Variability of aerosol and spectral lidar and backscatter and extinction ratios of key aerosol types derived from selected Aerosol Robotic Network locations

et al. 2005

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“…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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“…However, we assume that the particle is spherical for simplicity. When the particle size is micro scale, this simplicity is feasible as explained by Jaggard et al (1981) and Muñoz et al (2006). Table 4 lists the scattering efficiencies of calcite particles at wavelengths of 0.5 m and 10 m.…”

Section: Possibility Of Other Particle Materialsmentioning

confidence: 99%

Possibility for controlling global warming by launching nanoparticles into the stratosphere

Maruyama

Nagayama

Gonome

et al. 2015

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Light scattering from particles of regular and irregular shape

Cited by 43 publications

References 16 publications

Variability of aerosol and spectral lidar and backscatter and extinction ratios of key aerosol types derived from selected Aerosol Robotic Network locations

Variability of aerosol and spectral lidar and backscatter and extinction ratios of key aerosol types derived from selected Aerosol Robotic Network locations

Investigating biomass burning aerosol morphology using a laser imaging nephelometer

Possibility for controlling global warming by launching nanoparticles into the stratosphere

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