Sentinel-2 estimated patterns of Suspended Particle Size Distribution and Turbidity in a tidal dominated estuary.

Suspended particles are important constituents of the water column that are related to many physical, geochemical, and biological processes, such as flocculation, aggregation, and sediment resuspension. Very turbid and tidal dominated coastal waters represent a challenge for estimates of Suspended Particulate Matter (SPM) and Particle Size Distribution (PSD) because of the strong gradients observed in hydrodynamics (tidal processes, wind-driven waves) and sediment dynamics. This study uses the spectrum of satellite remote sensing reflectance data from Sentinel 2A,B sensors to yield SPM and PSD in the macrotidal Seine estuary and Bay (France). Five years (2016-2021) of Sentinel 2A,B are acquired from European Space Agency archive. The satellite timeseries will be atmospherically corrected, remapped to a standard projection and cloud-masked using the ACOLITE processor. Two different in-water bio-optical algorithms will be tested (the 2SeaColor and the approach similar to Shi and Wang 2019) to retrieve non-algal particle backscattering power law slope on a pixel-by-pixel basis. Then the three‐order polynomial function in Kostadinov et al. (2009) will be applied to the timeseries of backscattering power law slope to calculate the particle size slope. The time series of particle size slope will be used to provide the first systematic quantification of satellite-derived particle size variability from satellite remote sensing in the Seine estuary and Seine Bay. Spatial and temporal patterns of SPM and PSD variability on the satellite-derived data will be compared with 10 years-long in-situ observations (PSD from a LISST sensor and SPM) along with seasonal and interannual high resolution synoptic observations.