Fast hydrodynamic model for medium- and long-term dispersion in seawater in the English Channel and southern North Sea, qualitative and quantitative validation by radionuclide tracers

The main adjustment parameters of this model are the sources of wind data used and the calculation method for evaluating wind stress at the sea surface. With these parameters, the fluxes of radionuclides and water masses in the English Channel and the North Sea were balanced for the whole period of field measurements (1987-1994). The correlation factor between individual measurements in seawater and calculation results is 0.88 with an average error of ±54%, the error attributable to the measurement process being 15% on average. The mean flux through the Dover Strait is 126,000 m3 s−1, close from the one obtained from previous studies [Salomon, J.C., Breton, M., Guéguéniat, P. 1993. Computed residual flow through the Dover Strait. Oceanologica Acta 16 (5-6) (1993) 449-455; Bailly du Bois, P., Salomon, J.C., Gandon, R., Guéguéniat, P. 1995. A quantitative estimate of English Channel water fluxes into the North Sea from 1987 to 1992 based on radiotracer distribution. Journal of Marine Systems 6 (5-6) (1995) 457-481; Prandle, D., Ballard, G., Flatt, D., Harrison, A.J., Jones, S.E. Knight, P.J., Loch, S. McManus, J. Player, R. Tappin, A., 1996. Combining modelling and monitoring to determine fluxes of water, dissolved and particulate metals through the Dover Strait. Continental Shelf Research 16 (2) (1996) 237-257]. This model appears as a robust tool for modelling long-term dispersion at a low computation cost (it takes less than 1 h to simulate one year on a personal computer). It could forecast consequences of controlled or accidental releases of soluble substances in seawater under realistic conditions or calculate water masses fluxes and transit times.