A SEAWIFS ALGORITHM TO MEASURE LOW CONCENTRATIONS OF SUSPENDED MATTER IN THE ST. LAWRENCE ESTUARY

摘要

Since 1997, the Remote Sensing Laboratory of the Maurice-Lamontagne Institute (Dept. Of Fisheries and Oceans, Canada) has been conducting an ocean optics research program. This paper presents the development of an algorithm to evaluate total suspended sediment in the mixed type I and II waters of the St. Lawrence estuary and Gulf using SeaWiFS data. The algorithm was developped using a set of multispectral light profiles taken during an optics research cruise in 2001 and validated against 40 independent SeaWiFS overpass and in situ measurements taken during 4 other cruises (1997-2000). Many algorithms were tested but the best one is based on a regression of the total suspended sediment concentration with the 670 nm band. Results of the validation test show that the algorithm performs very well for the St. Lawrence sediment concentration range (0-3 mg l-1 -1) with a mean RMS error of 0,21 mg l-1 -1. This development now offers us a potential tool to evaluate the spatial and temporal variability of suspended sediment in the surface layer using the 7 years of available SeaWiFS data.