In situ evidence of non-zero reflectance in the OLCI 1020nm band for a turbid estuary

A spectroradiometer able to measure up to 2500nm has been used to measure the reflectance for the Ocean and Land Color Instrument (OLCI) 1020nm band. In July and October 2010 two measurement campaigns were organized at the Scheldt river to collect reflectance spectra and corresponding Total Suspended Matter (TSM) concentration and turbidity. A wide range of TSM concentration was covered from 15 to 402mgL−1. The measurements show a significant increase in reflectance between 950 and 1150nm, corresponding to a decrease in the pure water absorption coefficient. A high correlation was observed between the reflectance at 1020 and 1071nm and TSM concentration. The results were confirmed by simulations with Hydrolight and by the analysis of airborne Airborne Prism EXperiment (APEX) imagery. ► Above-water measurements of reflectance in the SWIR are presented. ► The results show a significant increase in reflectance between 950 and 1150nm. ► The OLCI 1020nm reflectance is correlated with TSM concentration. ► Hydrolight simulations and analysis of APEX imagery confirm the results.