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Modeling vs. satellite remote-sensing of near-surface non-algal suspended particulate matter in the English Channel.
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Edité par CCSD -
International audience. Concentration of near-surface suspended particulate matter (SPM) is a key parameter for the characterization of sediment dynamics and the quantification of light in the water column for hydrological and biological modeling in coastal seas. The influences of tides and wind-generated surface-gravity waves on non-algal near-surface SPM in the English Channel have recently been identified by Rivier et al. (2012) on the basis of statistical models applied to a large satellite dataset. The present study extends this analysis by comparing satellite images and numerical model predictions of non-algal near-surface SPM. Satellite images are MODIS and MERIS remote-sensing reflectance processed by the IFREMER semi-analytical algorithm (Gohin et al., 2011). These data have been provided through the MyOcean/GMES project. The numerical modeling approach is based on the three-dimensional (3D) hydro-sedimentary model ROMS (“Regional Ocean Model System”) (e.g., Warner et al., 2008). It considers realistic heterogeneous bottom sediments (Guillou and Chapalain, 2010), tidal forcing along open boundaries, wind stress at the sea-surface and wave-current interactions in the bottom boundary layer. Numerical results are compared with a series of “clear” satellite images gathered in 2008 under various tide and waves conditions. Modeling provides further insights of the spatio-temporal variability of non-algal surface SPM in the English Channel by resolving small-scale vertical transport processes and much shorter time-scales than daily satellite observation does. The granulometric distribution of non-algal near-surface SPM is examined. Finally, the focus is placed on two particular features: (i) the formation of a turbidity maximum zone around the Isle of Wight (English coastline) and (ii) the near-surface SPM variability in the Norman-Breton Gulf (French coastline).
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