Distribution Features And Influencing Factors In The Absorption And Scattering Efficiencies Of Suspended Particulate Matters In The Yellow Sea And Bohai Sea

The research on spatial distribution of the suspended particulates’absorption and scattering efficiencies and their influencing factors can help us deeply understand the nature of marine water. For example, it can help to built up bio-optical model, to improve the accuracy of water color remote sensing inversion parameters and to monitor the marine environment. In this paper, based on the in suit data from November 2014 (fall) and August 2015 (summer) in the Yellow Sea and Bohai with the measurements of spectral characteristics and space distribution characteristics (vertical and surface) of absorption and scatter, hydrological parameters, we analyzed the relationship between the absorption and scattering efficiency the particle size of the characteristics of suspended particulate matter, such as concentration, apparent density, size and composition. Our main findings are draw as followings:1) The spectral characteristics of absorption and scattering efficiency. The spectrum characteristics of absorption efficiency related to the composition of suspended particles in water. In the near-shore waters, which are dominated by inorganic particles, the absorption efficiency spectrum decreases with the wavelength; while in phytoplankton dominated offshore deep waters, the spectrum of absorption efficiency has an absorption efficiency peak at 440 nm and675 nm wavelength respectively. The spectral characteristics of scattering efficiency change very small and smooth with wavelength. Short-wave band scattering efficiency is slightly higher than in long wavelengths. Scattering efficiency is low in summer, while higher in autumn.2) The spatial distribution of absorption efficiency and scattering efficiency. Inshore water absorption efficiency is horizontal higher in summer, while offshore deep water’s absorption efficiency is low; In autumn, absorption efficiency of near-shore waters is low but high in offshore, which is mainly affected by the growth of phytoplankton. Scattering efficiency is high in near-shore waters, while far from the shore waters scattering efficiency is low in horizontal. In autumn, scattering efficiency is higher than in summer. For vertical profile, both absorption efficiency and scattering efficiency in the Yellow sea and Bohai sea on the vertical section depth are obvious stratified in summer. There in upper layer are low but high in deep layer. In autumn, both absorption efficiency and scattering efficiency of waters with depths< 50 m are relatively uniform, while the depth more than 50 m showed obvious hierarchical structure. In the upper layer, scattering efficiency is low but high in deep layer.3) The influence factors of absorption efficiency and scattering efficiency. The suspended particulate matters in the Yellow Sea and Bohai Sea mainly affected by phytoplankton growth reproduction, sediment re-suspension caused by tidal current and the vertical hybrid effect. Different processes produce different types of suspended particulate matter which cause distinct absorption efficiency and scattering efficiency. Absorption efficiency is mainly affected by chlorophyll concentration together with the suspended particle size and apparent density. The contribution of each influence factor on the absorption efficiency also varies. The contribution of chlorophyll concentration on the variability in absorption efficiency is about 33%, while the particle size contributes 37% variations; the contributions of apparent density and particle size to the changes of absorption efficiency are about 14%. The scattering efficiency is mainly affected by the suspended particle concentration, particle size and apparent density. The contribution of particle size on the variability in the scattering efficiency is about 15%, and the changes of the apparent density explained 20% variations of the scattering efficiency.