title: Optical scattering and backscattering by organic and inorganic particulates in U.S. coastal waters.
abstract: We present the results of a study of optical scattering and backscattering of particulates for three coastal sites that represent a wide range of optical properties that are found in U.S. near-shore waters. The 6000 scattering and backscattering spectra collected for this study can be well approximated by a power-law function of wavelength. The power-law exponent for particulate scattering changes dramatically from site to site (and within each site) compared with particulate backscattering where all the spectra, except possibly the very clearest waters, cluster around a single wavelength power-law exponent of -0.94. The particulate backscattering-to-scattering ratio (the backscattering ratio) displays a wide range in wavelength dependence. This result is not consistent with scattering models that describe the bulk composition of water as a uniform mix of homogeneous spherical particles with a Junge-like power-law distribution over all particle sizes. Simultaneous particulate organic matter (POM) and particulate inorganic matter (PIM) measurements are available for some of our optical measurements, and site-averaged POM and PIM mass-specific cross sections for scattering and backscattering can be derived. Cross sections for organic and inorganic material differ at each site, and the relative contribution of organic and inorganic material to scattering and backscattering depends differently at each site on the relative amount of material that is present.
authors.affiliation: Code 7230, US Naval Research Laboratory, Washington, DC 20375-5320, USA. William.Snyder@nrl.navy.mil
authors.forename: William A
authors.initials: WA
authors.lastname: Snyder
authors.forename: Robert A
authors.initials: RA
authors.lastname: Arnone
authors.forename: Curtiss O
authors.initials: CO
authors.lastname: Davis
authors.forename: Wesley
authors.initials: W
authors.lastname: Goode
authors.forename: Richard W
authors.initials: RW
authors.lastname: Gould
authors.forename: Sherwin
authors.initials: S
authors.lastname: Ladner
authors.forename: Gia
authors.initials: G
authors.lastname: Lamela
authors.forename: William J
authors.initials: WJ
authors.lastname: Rhea
authors.forename: Robert
authors.initials: R
authors.lastname: Stavn
authors.forename: Michael
authors.initials: M
authors.lastname: Sydor
authors.forename: Allen
authors.initials: A
authors.lastname: Weidemann
mesh_terms: D000042:Absorption; D004784:Environmental Monitoring / Q000379:methods; D005583:Fourier Analysis; D007287:Inorganic Chemicals / Q000032:analysis*; D008027:Light; D008962:Models, Theoretical; D009930:Organic Chemicals / Q000032:analysis*; D010316:Particle Size; D052638:Particulate Matter / Q000032:analysis*; D012031:Refractometry; D012542:Scattering, Radiation; D014481:United States; D014867:Water / Q000032:analysis* / Q000737:chemistry; D014874:Water Pollutants, Chemical / Q000032:analysis
chemical_list: D007287:Inorganic Chemicals; D009930:Organic Chemicals; D052638:Particulate Matter; D014874:Water Pollutants, Chemical; D014867:Water