Estimation of colored dissolved organic matter using Sentinel-2 data in the coastal waters of Singapore

In coastal waters, colored dissolved organic matter (CDOM) is often present in moderate to high concentrations due to input from nearby landmasses and rivers. CDOM absorbs light sharply in the UV-blue region, causing waters to appear yellow or brown. This has a significant effect on optical and biogeochemical processes in coastal waters, as it inhibits the penetration of light within the water. It is thus important to be able to monitor CDOM levels on a regular basis. A model is presented linking Sentinel-2 reflectance data to the CDOM absorption coefficient. Such a model is useful for monitoring the CDOM absorption in coastal waters due to the frequency of Sentinel-2 passes and relatively high-spatial resolution. This model was developed and validated using concurrent field measurements of above-surface remote-sensing reflectance and the in situ CDOM absorption coefficient, from the coastal waters of Singapore. The leave-one-out cross-validation scheme was used to validate the model due to the small number of data points. The model is further tested with Sentinel-2 images of the same locations, not more than one day apart from the in situ measurements. (C) 2020 Society of Photo-Optical Instrumentation Engineers (SPIE)