Variability of the relationship between the particulate backscattering coefficient and the volume scattering function measured at fixed angles

Chami, Malik; Marken, Endre; Stamnes, Jakob J.; Khomenko, G. A.; Коротаев, Г. К.

doi:10.1029/2005jc003230

Cited by 52 publications

(51 citation statements)

References 24 publications

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“…For example, Sullivan et al (2005) derived a value of 0.90 ± 0.01 at 125 • from experimental measurements of the volume scattering function at three angles. On the other hand, Chami et al (2006) derived a χ p (117 • ) factor of 1.29 ± 0.01 from in-situ measurements in the Black Sea and showed that phytoplankton cultures can display relatively large interspecific differences in χ p . In addition, the data presented by Chami et al (2006) suggest that χ p could be spectrally dependent.…”

Section: χ P Factormentioning

confidence: 99%

“…On the other hand, Chami et al (2006) derived a χ p (117 • ) factor of 1.29 ± 0.01 from in-situ measurements in the Black Sea and showed that phytoplankton cultures can display relatively large interspecific differences in χ p . In addition, the data presented by Chami et al (2006) suggest that χ p could be spectrally dependent. Note, however, that by definition the angular mean value of χ −1 p in the backscattering direction has to be 1.…”

Section: χ P Factormentioning

confidence: 99%

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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: χ P Factormentioning

confidence: 99%

Section: χ P Factormentioning

confidence: 99%

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

et al. 2009

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“…There is less agreement about the behavior of χ at larger scattering angles. Some studies reported lower values for χ(170 • ) [12,13,16], but most do not [13,[15][16][17]. The most recent laboratory measurements, made out to 175 • , are significantly lower, reporting χ(175 • ) < 0.01 for several phytoplankton species and χ(175 • ) = 0.2 for Arizona road dust [21].…”

Section: Introductionmentioning

confidence: 97%

“…Both field [12][13][14][15]17] and laboratory [13,16,21] studies have shown that the variability in χ is minimum at a scattering angle near 120 • . Most studies report χ(120 • ) = 1.10-1.13 with a variability of a few % [12][13][14][15][16][17]. There is less agreement about the behavior of χ at larger scattering angles.…”

Section: Introductionmentioning

confidence: 99%

“…In situ measurement of b bp is facilitated by the fact that, because the variability in the shape of the particulate volume scattering function at scattering angles >90 • is relatively low [11][12][13][14][15][16][17], a relationship between the particulate backscattering coefficient and volume scattering functions that can be expressed as [12][13][14][15][16][17] …”

Section: Introductionmentioning

confidence: 99%

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Optical Backscattering Measured by Airborne Lidar and Underwater Glider

et al. 2017

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Abstract:The optical backscattering from particles in the ocean is an important quantity that has been measured by remote sensing techniques and in situ instruments. In this paper, we compare estimates of this quantity from airborne lidar with those from an in situ instrument on an underwater glider. Both of these technologies allow much denser sampling of backscatter profiles than traditional ship surveys. We found a moderate correlation (R = 0.28, p < 10 −5 ), with differences that are partially explained by spatial and temporal sampling mismatches, variability in particle composition, and lidar retrieval errors. The data suggest that there are two different regimes with different scattering properties. For backscattering coefficients below about 0.001 m −1 , the lidar values were generally greater than the glider values. For larger values, the lidar was generally lower than the glider. Overall, the results are promising and suggest that airborne lidar and gliders provide comparable and complementary information on optical particulate backscattering.

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Can we use satellites to calibrate airborne lidar?

Churnside¹,

Marchbanks²

2018

Preprint

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The backscattering coefficient of seawater, defined as the coefficient of scattering at angles > 90 degrees, includes contributions from water and from any particles in the water. The water contribution has a relatively narrow range of values in the ocean, but the particulate contribution depends on the number of particles in the water and their type. Measurements of the particulate backscattering coefficient generally take advantage of the relatively small variability in scattering with angle at angles > 90 degrees to obtain an estimate of the backscattering coefficient from scattering at a single angle. Lidar has been used to infer the backscattering coefficient from scattering at 180 degrees, but this depends on knowledge of the relationship between scattering at this angle and the backscattering coefficient. It also depends on an absolute radiometric calibration, although this can be avoided using high-spectral-resolution lidar. Here, we consider a technique to obtain the backscattering coefficient directly from lidar data by calibration against passive ocean color measurements. The technique does not depend on retrieval of either the lidar calibration coefficient or the relationship between the volume scattering function at 180 degrees and the backscattering coefficient, but can be used to infer both quantities. The only requirement is that the relationship between the scattering parameters not change significantly over the area, depth range, or duration of the measurements. Once the relationship is found, it can be used where the satellite measurements are affected by clouds or vertical structure in the scattering.

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Variability of the relationship between the particulate backscattering coefficient and the volume scattering function measured at fixed angles

Cited by 52 publications

References 24 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

Optical Backscattering Measured by Airborne Lidar and Underwater Glider

Can we use satellites to calibrate airborne lidar?

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