Retrieval of the seawater reflectance for suspended solids monitoring in the East China Sea using MODIS, MERIS and GOCI satellite data

The objectives of this study are to: (i) compare the potential of the Moderate Resolution Imaging Spectroradiometer (MODIS), the Medium Resolution Imaging Spectrometer (MERIS) and the Geostationary Ocean Color Imager (GOCI) in retrieving the particulate backscattering coefficient, robust proxy of the concentration of suspended particulate matter (SPM), in the turbid waters of the East China Sea, then (ii) combine ocean color satellite data to field data recorded by an autonomous bio-optical profiling float to reconstitute and explain the dynamics of SPM within the whole water column in the middle of the East China Sea. MODIS, MERIS and GOCI seawater reflectance products at green, red and near-infrared (NIR) wavelengths are generated using atmospheric correction algorithms designed for turbid coastal waters then compared. Good agreement is obtained in the green and red while significant differences are observed in the NIR. The standard GOCI algorithm and a new one based on a regional empirical relationship established using MODIS satellite data are both proved to perform well over the whole range of water turbidity. Finally the dynamics of SPM is reconstituted along a three-month period to highlight a steady-state and stratified situation before the overpass of a large typhoon which mixed the water column, destroyed the deep-chlorophyll maximum and enhanced resuspension of bottom sediments varying according to tidal cycles.