Characterization Of Bio-Optical Properties And Their Interrelationships In Southern South China Sea

Abstract

This study focuses on the variability and relationships of bio-optical properties with optically active constituents in the southern South China Sea. On these bases, the applicability and the limits of reliability of satellite ocean colour algorithm in this study area were also assessed. To achieve this goal, two study areas with distinct bio-optical conditions: Brunei Bay (BB) coastal water which characterized by high riverine discharge, strong phytoplankton blooms and suspended particles, and east coast of peninsular Malaysia (ECPM) water with relatively low chlorophyll and suspended particle concentrations; were intensively investigated. In both study areas, in-situ measurements of underwater radiation fields, in-water constituents and absorption properties were conducted during bio-optical cruises in January and May 2014. The analyses of data revealed a significant variation in bio-optical properties between BB and ECPM waters. High concentrations in both constituents and optical properties were observed in BB while ECPM is characterized by relatively low concentration of constituents and weak optical signals. Differences in bio-optical properties between both study areas are clearly showed by variation in phytoplankton specific absorption coefficients; very high values for low chlorophyll in ECPM and low values for relatively high chlorophyll in BB, an indicator of strong package effect. In both areas, the result found that coloured dissolved organic matter (CDOM) is the most dominant absorber, contributing about 65% in ECPM and 77% in BB, and this suggests the significant important of CDOM in determining the reflectance signal in this study area. Due to very high concentrations of non-pigmented particles in BB, the shape and magnitude of absorption properties and reflectance signal are found to be significantly different as compared to results observed in ECPM.