A reflectance band ratio used to estimate suspended matter concentrations in sediment-dominated coastal waters
This letter presents an empirical relationship that may be used to estimate the suspended particulate matter concentrations in highly turbid waters from remote sensing reflectance measurements. Numerous measurements carried out in the Gironde estuarine waters (France) in 2000 and 2001 are presented and analysed. It was observed that the near-infrared (850 nm) reflectance was weakly correlated with the total suspended matter concentration (TSMc) measured in surface waters. A strong correlation (r=0.91) was obtained between the ratio of the near-infrared and visible (550 nm) reflectance and TSMc, which could provide an accurate calibration curve for data from Systeme Probatoire de l'Observation de la Terre (SPOT), Landsat and Indian Remote Sensing (IRS) satellite sensors. The reflectance ratio reduced the effects of changes in illumination conditions and sediment type (grain-size, refractive index). The calibration function obtained, successfully applied to the Gironde, should be applied in other sedimentdominated coastal waters.