Light beam attenuation and backscattering properties of particles in the Bohai Sea and Yellow Sea with relation to biogeochemical properties

Abstract

Abstract This study reports the first results of the variability in light beam attenuation and the backscattering properties of particles and their controlling factors during the summer in the Bohai Sea (BS) and Yellow Sea (YS), which are two typical shallow and semienclosed seas. We observe large variations in the particulate beam attenuation ( c p ) and backscattering coefficients ( b bp ); such variations are mainly attributed to changes in the total suspended matter, while the cross‐sectional area concentration shows tighter relationships with both c p and b bp . The mass‐specific beam attenuation ( ) and backscattering coefficients ( ) vary more widely over about two orders of magnitude. The attenuation ( Q ce ) and backscattering efficiencies ( Q bbe ) are important factors that control and , which clearly separate all the samples into two types. Type 1 samples show low Q ce and Q bbe and contain relatively high proportions of organic or large particles, while type 2 samples have high Q ce and Q bbe and mainly contain relatively small mineral particles. The majority of the variability in and within each type is related to the inverse of the product of particle apparent density ( ρ a ) and mean diameter ( D A ); ρ a plays a major role, while D A exerts only a slight impact. Overall, this study provides general knowledge of particulate beam attenuation and the backscattering properties in the BS and YS, which may improve our understanding of underwater radiative transfer processes, marine biogeochemical processes and ocean color algorithms.