Backscattering by nonspherical particles: A review of methods and suggested new approaches

Bohren, Craig F.; Singham, Shermila Brito

doi:10.1029/90jd01138

Cited by 87 publications

(51 citation statements)

References 41 publications

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“…Theoretical models that account for internal structure and non-sphericity of the particles predict backscattering coefficients significantly higher (up to an order of magnitude) than those expected for equivalent homogeneous spheres (Meyer, 1979;Bohren and Singham, 1991;Kitchen and Zaneveld, 1992;Quirantes and Bernard, 2004;Clavano et al, 2007). Moreover, direct laboratory measurements of the backscattering coefficient (or the volume scattering function) of phytoplankton cultures are also in disagreement with predictions based on the homogeneous spherical model.…”

Section: G Dall'olmo Et Al: Particulate Backscattering In the Oceanmentioning

confidence: 54%

Significant contribution of large particles to optical backscattering in the open ocean

et al. 2009

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Abstract. The light scattering properties of oceanic particles have been suggested as an alternative index of phytoplankton biomass than chlorophyll-a concentration (chl-a), with the benefit of being less sensitive to physiological forcings (e.g., light and nutrients) that alter the intracellular pigment concentrations. The drawback of particulate scattering is that it is not unique to phytoplankton. Nevertheless, field studies have demonstrated that, to first order, the particulate beam-attenuation coefficient (c p ) can track phytoplankton biomass. The relationship between c p and the particulate backscattering coefficient (b bp ), a property retrievable from space, has not been fully evaluated, largely due to a lack of open-ocean field observations. Here, we present extensive data on inherent optical properties from the Equatorial Pacific surface waters and demonstrate a remarkable coherence in b bp and c p . Coincident measurements of particle size distributions (PSDs) and optical properties of sizefractionated samples indicate that this covariance is due to both the conserved nature of the PSD and a greater contribution of phytoplankton-sized particles to b bp than theoretically predicted. These findings suggest that satellite-derived b bp could provide similar information on phytoplankton biomass in the open ocean as c p .

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Section: G Dall'olmo Et Al: Particulate Backscattering In the Oceanmentioning

confidence: 54%

Significant contribution of large particles to optical backscattering in the open ocean

et al. 2009

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show abstract

“…Our understanding of the major contributors to b bp in natural waters is uncertain and it is unknown which particles backscatter light most efficiently . Mie scattering theory suggests substantial contributions to b bp from submicron particles (Stramski and Kiefer 1991), but there is strong evidence that application of this model is inappropriate for computations of b bp for natural particle assemblages (Bohren and Singham 1991;Kitchen and Zaneveld 1992;Clavano et al 2007). In situ measurements of bulk and sizefractionated measurements of b bp in the open ocean showed strong contributions to b bp from particles larger than 3 mm and negligible contributions from particles below 0.2 mm (Dall'Olmo et al 2009 (Deyong et al 2009;Martinez-Vicente et al 2010).…”

mentioning

confidence: 99%

In situ variability of mass‐specific beam attenuation and backscattering of marine particles with respect to particle size, density, and composition

Neukermans

Loisel

Mériaux

et al. 2011

Limnology & Oceanography

181

179

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This study analyzes relationships between concentration of suspended particles represented by dry mass, [SPM], or area, [AC], and optical properties including particulate beam attenuation (c p ), side scattering (b s ), and backscattering (b bp ), obtained from an intensive sampling program in coastal and offshore waters around Europe and French Guyana. First-order optical properties are driven by particle concentration with best predictions of [SPM] by b bp and b s , and of [AC] by c p . Second-order variability is investigated with respect to particle size, apparent density (dry weight-to-wet-volume ratio), and composition. Overall, the mass-specific particulate backscattering coefficient, b bp remains unexplained. Possible causes are the limitation of the measured size distributions to the 2-302-mm range and effects of particle shape and internal structure that affect b bp more than c p and were not accounted for.

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“…Although the applicability of Mie theory to the determination of backscattering is known to be limited (Bohren and Singham 1991), it is the only available theory, and, hence, it is often used. Semi-analytical models of backscattering by oceanic particles often adjust their parameterizations in order to have, for instance, spectral changes of b bp that respect Mie theory predictions (Morel and Maritorena 2001).…”

mentioning

confidence: 99%

Variability in optical particle backscattering in contrasting bio‐optical oceanic regimes

Antoine¹,

Siegel²,

Kostadinov³

et al. 2011

Limnology & Oceanography

100

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Variability in the optical particle backscattering coefficient (b bp ) is investigated in oceanic waters from two sites, namely the BOUée pour l'acquiSition d'une Série Optique à Long termE site in the northwestern Mediterranean Sea and the Plumes and Blooms stations in the Santa Barbara Channel off Southern California. Data from these two sites span two orders of magnitude in b bp and likely cover typical open ocean values. A significant relationship is found between b bp at wavelengths of 442 and 555 nm and chlorophyll concentration. However the large spread in this relationship makes chlorophyll a poor predictor of b bp . The relationship between b bp and the particulate beam attenuation coefficient at 660 nm is tighter for both sites, indicating covariability of the particle size ranges that determine both coefficients. A detailed study of the seasonal changes of the b bp vs. chlorophyll relationship reveals that this bio-optical relationship might be best described as a succession of distinct regimes with rapid transitions from one to another. The backscattering ratio (b bp ; the ratio of b bp to total particulate scattering, b p ) ranges from about 0.2% to 1.5%, which is similar to previously reported values. The relationship between b bp and chlorophyll was not significant, while values of the backscattering ratio varied spectrally.

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Backscattering by nonspherical particles: A review of methods and suggested new approaches

Cited by 87 publications

References 41 publications

Significant contribution of large particles to optical backscattering in the open ocean

Significant contribution of large particles to optical backscattering in the open ocean

In situ variability of mass‐specific beam attenuation and backscattering of marine particles with respect to particle size, density, and composition

Variability in optical particle backscattering in contrasting bio‐optical oceanic regimes

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