Using MERIS for the retrieval of suspended sediments in optically complex waters
07 March 2014
Estuaries along many of the world's diverse coastlines, support important ecosystem functions and services. They are complex environments, in which dissolved, and suspended particulate matter (SPM), discharged by rivers in upland basins are concentrated and mixed with marine waters and their dissolved and suspended substances.
In this study, ENVISAT MERIS data were used to investigate: first, how large-scale estuarine SPM concentrations were affected by tidal and meteorological drivers; and, second, how retrieved SPM is biased by tidal aliasing and sampling under clear sky conditions.
Spectral absorption and scattering have been used to derive SPM concentration maps from 84 MERIS Full Resolution reflectance images, which had been acquired during different tidal and seasonal conditions, for 2006 to 2008. By grouping the data collected under similar tidal or meteorological conditions, the study reveals how spatial patterns in SPM are related to tidal phases, and seasonal variability. These tidal phases are regularly cyclic and can be well-predicted, while bulk meteorological variability is much less regular, but follows a seasonal cycle. Based on the spatial variation in SPM from satellite images, the scientists established that tidal and seasonal effects on the variation of SPM are similar in magnitude for the estuary proper.