The research objective is a better understanding of the inherent optical properties (IOP) of highly turbid waters (i.e. rivers, estuaries and turbid plumes), where properties of suspended sediments are predominant. An IOP model will be developed, including notably the Mie theory to compute scattering optical properties of sediments as a function of sediment type (grain size distribution, refractive index). New techniques will be based on: video camera records to detennine in situ grain-size variations; improved measurements of optical properties in different highly turbid waters, using AC-9 and BB-4sensors, to quantify the absolution due to sediment and validate the IOP model. Numerous field reflectance measurements, taken in different geographical regions, will be integrated into a theoretical appropriate reflectance band ratios and suspended sediment concentration (SSC) will be established in each study area. Theoretical and empirical results will then be used m the development of improved algorithms for quantification of SSC from satellite (SPOT, Landsat, MERIS and CHRIS-PROBA)and airborne (CASI) remotely sensed data. The satellite and airborne imagery will be atmospherically corrected, using recently developed schemes, prior to the application of SSC algorithms.
The selected study areas are the Gironde and Loire estuaries (in France) with the Humber and Tarnar estuaries (in UK), but the modelling results will be globally applicable. The training includes field campaigns in the different selected estuaries, to determine sediment types(grain-size distribution, mineral composition), measure water reflectance and lOPs. Recently developed sensors (video camera system, multi-band radiometers, AC-9 and BB-4) will be used, which will give me a great experience in collecting and processing of optical data. The training will also include a theoretical approach of marine optics applications, by validating IOP and reflectance models in highly turbid waters. Finally, results will lead to the development of original and improved algorithms for satellite and airborne sensors. Remotely sensed data recorded from selected study areas will be processed in order to retrieve SSC. This experience will greatly contribute to my development as a postdoctoral researcher. The benefits of these works for the host institution will be a better understanding of IOPs in highly turbid waters (notably optical properties of sediments), and the application of new algorithms to recently launched satellite sensors (e.g. MERIS & CHRIS-PROBA).