Empirical ocean colour algorithms for estimating sea surface salinity in coastal water of terengganu

This study presents an empirical approach for estimating sea surface salinity (sss) from remote sensing of ocean colour. the analysis is based on two important empirical relationships of in-water optical properties. the first involves the behaviour of the optical properties of coloured dissolved organic matter (cdom) under conservative mixing along the salinity gradient. the second is the tight relationship between cdom and water-leaving radiance. our results showed that cdom absorption coefficients in ultra-violet wavelengths (350 and 380 nm) can be best estimated using the blue-green band ratio rrs(412/547) with a r2 value of 0.87. it was also found that the absorption coefficient of cdom in the study area was tightly correlated with the salinity (r2≈0.83); however,the data indicate that this relationship may be dependent on freshwater flow and the intensity of vertical mixing. during the wet and well-mixed season (northeast monsoon),cdom was almost conservative with salinity but tended to behave non-conservatively during the dry and stratified season (southwest monsoon). these resulting empirical relationships allow cdom and salinity in the study area to be estimated from satellite ocean colour data. validation using independent datasets showed that the algorithms for cdom and salinity perform relatively well with the rms error of 0.04 m-1 and 0.30`,respectively,over a range of salinity from 30` to 33`. the ability of the algorithm to predict salinity as those presented in this study can be further improved using more independent tests with in-situ and satellite bio-optical measurements. © 2017 universiti putra malaysia press.