TriOS underwater spectrum measurement system and its application

Abstract

Light is very important for water ecosystem, it was attenuated because of absorption and scatter caused by suspend sediment, chlorophyll and colored dissoluble organic matter(CDOM) in water. Water remote sensing reflectance is an important parameter for ocean color remote sensing, which has good relation with water quality. Measure underwater spectrum has significance application value for water ecosystem research and water quality retrieval. This paper introduced the TriOS spectrum measurement system firstly, then use the in situ data collected by the system in Taihu Lake to retrieval suspended sediment(SS) concentration. First, underwater remote sensing reflectance(Rrs(0 - )) was calculated by using the underwater spectra, then transform the Rrs(0 - ) into Rrs(0 + ) based on water-air interface transmission model, after that analysis the relativity between SS concentration and Rrs(0 + ), and finally suspend sediment retrieval models were developed. Compare different models, in order to select an optimal model for retrieving SS concentration. The result indicates that: Rrs(0 + ) has good relationship with the logarithm of SS concentration(Ln(SS)). In spectral region 500nm-600nm, there present negative correlation, and present well positive correlation in spectral region 620nm-882nm. The maximal correlation coefficient locates at band 743nm. Take Rrs(522), Rrs(743), Rrs(815) as independent variable to build SS concentration retrieval models, the retrieval results showed that logarithm model is better than other models, it can satisfied the require of practical application to certain extent.