Benefit of the potential future hyperspectral satellite sensor (BIODIVERSITY) for improving the determination of water column and seabed features in coastal zones
Résumé
Most of the studies dealing with seabed mapping from hyperspectral images have been carried out using airborne data although hyperspectral satellite sensors have already been or are planned to be launched for the near future (HICO ENMAP or BIODIVERSITY). The objective of this study is to evaluate the benefit of a BIODIVERSITY-like sensor to determine the bio-optical properties of the water column, namely the Chlorophyll-a concentration, the Suspended Particulate Matter concentration, the absorption coefficient of the Colored Dissolved Organic Matter, the bathymetry and the composition of the seabed, according to its spatial resolution and spectral resolution and its Signal to Noise Ratio (SNR). For this purpose, radiative transfer simulations are analyzed together with remote sensing hyperspectral airborne data (HYSPEX) acquired above the Porquerolles Island (France). The retrieval performance of all in-water and seabed parameters derived from the inversion of BIODIVERSITY-like data is compared with the performance obtained using ENMAP and HICO spatial and radiometric specifications. It is shown that a BIODIVERSITY-like sensor significantly improves the estimation performance of the water column parameters. Furthermore, BIODIVERSITY-like sensor is highly appropriate for seabed mapping when bottom pixels are composed of pure material (e.g., Sand or Posidonia) in shallow waters when seabed depth is less than 10 m. Conversely, the performance of the inversion deteriorates when seabed pixels are composed of mixed materials (e.g., Sand mixed with Posidonia). It is also shown that the concentration of chlorophyll, SPM and CDOM absorption are less sensitive to noise level than depth and seabed abundance.
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