Evidence for wavelength dependence of the scattering phase function and its implication for modeling radiance transfer in shelf seas

McKee, David; Cunningham, Alex

doi:10.1364/ao.44.000126

Cited by 35 publications

(31 citation statements)

References 19 publications

(17 reference statements)

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“…Under certain conditions, however, enhancedb bp in blue wavelengths has been measured (McKee and Cunningham, 2005), similar to that found at the whitings station. Conditions that might cause wavelength-dependence would occur when the particle size distribution contains modes of particles and the particle size distribution does not closely follow a Jungian or power-law distribution.…”

Section: Optical Characterization Of Whitingssupporting

confidence: 77%

Optics and remote sensing of Bahamian carbonate sediment whitings and potential relationship to wind-driven Langmuir circulation

2009

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Abstract.Regions of milky white seas or "whitings" periodically occur to the west of Andros Island along the Great Bahama Bank where the bottom sediment consists of finegrained aragonite mud. We present measurements of inherent optical properties within a sediment whiting patch and discuss the potential for monitoring the frequency, extent, and quantity of suspended matter from ocean colour satellite imagery. Sea spectral reflectance measured in situ and remotely from space revealed highly reflective waters elevated across the visible spectrum (i.e., "whitened") with a peak at 490 nm. Particulate backscattering was an order of magnitude higher than that measured at other stations throughout the region. The whiting also had one of the highest backscattering ratios measured in natural waters (0.05-0.06) consistent with water dominated by aragonite particles with a high index of refraction. Regular periodicity of 40 and 212 s evident in the light attenuation coefficient over the sampling period indicated patches of fluctuating turbidity on spatial scales that could be produced from regular rows of Langmuir cells penetrating the 5-m water column. We suggest that previously described mechanisms for sediment resuspension in whitings, such as tidal bursting and fish activity, are not fully consistent with these data and propose that wind-driven Langmuir cells reaching the full-depth of the water column may represent a plausible mechanism for sediment resuspension and subsequent whiting formation. Optics and remote sensing provide important tools for quantifying the linkages between physical and biogeochemical processes in these dynamic shallow water ecosystems.

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Section: Optical Characterization Of Whitingssupporting

confidence: 77%

Optics and remote sensing of Bahamian carbonate sediment whitings and potential relationship to wind-driven Langmuir circulation

2009

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“…In contrast, oceanic waters dominated by phytoplankton and covarying byproducts typically range from 0.005 to 0.01 (Twardowski et al, 2001;Boss et al, 2004;Sullivan et al, 2005), while coastal waters with suspended sediments typically do not exceed 0.025 (Twardowski et al, 2001;Boss et al, 2004;Sullivan et al, 2005;McKee et al, 2009;Doxaran et al, 2012). However, values up to 0.05 were observed by McKee and Cunningham (2005) in the Irish and Celtic Seas and values up to 0.036 were observed in the eastern English Channel and southern North Sea (Lubac and Loisel, 2007), in the same range as our measurements from the MB. In our data set, the highest b bp values were associated with stations where cyanobacteria were present.…”

Section: Particle Scattering and Backscatteringsupporting

confidence: 72%

Bio-optical Properties of Cyanobacteria Blooms in Western Lake Erie

et al. 2017

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There is a growing use of remote sensing observations for detecting and quantifying freshwater cyanobacteria populations, yet the inherent optical properties of these communities in natural settings, fundamental to bio-optical algorithms, are not well known. Toward bridging this knowledge gap, we measured a full complement of optical properties in western Lake Erie during cyanobacteria blooms in the summers of 2013 and 2014. Our measurements focus attention on the optical uniqueness of cyanobacteria blooms, which have consequences for remote sensing and bio-optical modeling. We found the cyanobacteria blooms in the western basin during our field work were dominated by Microcystis, while the waters in the adjacent central basin were dominated by Planktothrix. Chlorophyll concentrations ranged from 1 to over 135 µg/L across the study area with the highest concentrations associated with Microcystis in the western basin. We observed large, amorphous colonial Microcystis structures in the bloom area characterized by high phytoplankton absorption and high scattering coefficients with a mean particle backscatter ratio at 443 nm > 0.03, which is higher than other plankton types and more comparable to suspended inorganic sediments. While our samples contained mixtures of both, our analysis suggests high contributions to the measured scatter and backscatter coefficients from cyanobacteria. Our measurements provide new insights into the optical properties of cyanobacteria blooms, and indicate that current semi-analytic models are likely to have problems resolving a closed solution in these types of waters as many of our observations are beyond the range of existing model components. We believe that different algorithm or model approaches are needed for these conditions, specifically for phytoplankton absorption and particle backscatter components. From a remote sensing perspective, this presents a challenge not only in terms of a need for new algorithms, but also for determining when to apply the best Moore et al. Lake Erie IOPs algorithm for a given situation. These results are new in the sense that they represent a complete description of the optical properties of freshwater cyanobacteria blooms, and are likely to be representative of bloom conditions for other systems containing Microcystis cells and colonies.

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“…The spectra can be attributed to micron-sized aragonite particles. The backscatter variation across the spectra related earlier to wave forcing has been previously observed for whiting events (Dierssen et al 2009, McKee andCunningham, 2005) and has been suggested as resulting from a dominance of a single particle type.…”

Section: Resultssupporting

confidence: 54%

Hydrodynamic Controls on Acoustical and Optical Water Properties in Tropical Reefs

Pawlak¹,

Moline²

2013

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Evidence for wavelength dependence of the scattering phase function and its implication for modeling radiance transfer in shelf seas

Cited by 35 publications

References 19 publications

Optics and remote sensing of Bahamian carbonate sediment whitings and potential relationship to wind-driven Langmuir circulation

Optics and remote sensing of Bahamian carbonate sediment whitings and potential relationship to wind-driven Langmuir circulation

Bio-optical Properties of Cyanobacteria Blooms in Western Lake Erie

Hydrodynamic Controls on Acoustical and Optical Water Properties in Tropical Reefs

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