Sediment dynamics in the Black Sea: numerical modelling and remote sensing observations

Abstract

Here, we address the sediment dynamics in the Black Sea based on analysis of remote sensing data from the Medium Resolution Imaging Spectrometer and numerical simulations with Nucleus for European Modelling of the Ocean model. Boundary conditions consist of realistic meteorological forcing, including significant wave height generated by wave prediction model. A number of sensitivity runs was analysed with the aim to find the most suitable parameters governing sediment fluxes. The comparison between numerical simulations and remote sensing data gives credibility to the quality of simulations. The combined effect of wind waves and currents in the bed layer controls the sediment resuspension that appears to be the major basin-wide source of sediment. Sensitivity experiments included or excluded different forcing terms, e.g. sediment flux from rivers enable to determine the spatial extensions of different point sources. It is concluded that wind-wave forcing is manifested in the sediment dynamics through episodic high energy events contributing to the increase of horizontal sediment fluxes over the northwestern shelf. Both satellite images and numerical model simulations demonstrated that the penetration of suspended sediment into the basin interior was governed by the dynamics of coastal and open-ocean eddies. While fine sediment at sea surface could cross the continental slope propagating into the open ocean, coarser fractions follow the bottom and their penetration into the open ocean is limited. The conclusion is thus that the deposition patterns correlate with the specific shape of Black Sea topography, and the largest depositions are observed in the area of continental slope.