The second term defines the rate of water release and decreases with increasing content of asphaltenes, wax and surfactants in the oil and with

increasing oil viscosity. Vertical transport of oil into the water column can be accomplished by a number of mechanisms, such as dissolution, dispersion, accommodation and sedimentation. The model accounts only for natural dispersion and treats it as an entrainment process, whereby the formation of an oil-in-water emulsion is a consequence of increased turbulence in the surface layer. According to Mackay et al. (1980), vertical dispersion can be estimated check details as the fraction of the sea surface that is dispersed in the water column per unit time, using the following equation: equation(10a, b, c) D0=DDDEN;DD=0.111+Uw23600;DEN=11+0.5μhγEN, where DD accounts for the dispersed fraction of the sea surface into the water column per second, and DEN accounts for the fraction of the dispersed Cilengitide oil not returning to the surface oil slick. The symbol h stands for the oil slick thickness [m], and γEN is the oil-water

interfacial tension [N m− 1] for the entrainment parameterization. The rate of upwelling of dispersed oil droplets is calculated from equation(11) dVdt=0.111+Uw−AV236001−11+0.5μhγEN. The term Uw − AV in (10a, b, c) and (11) represents the spatially averaged wind speed from a 2D wind field that is also used in the sea circulation model. However, such a simplification neglects inhomogeneous surface wave breaking, and consequently, induced inhomogeneous turbulence in the sea surface layer (inhomogeneous intensity of natural dispersion). The rate of oil entrainment from the slick to the water column can be scaled as (Tkalich & Chan 2002): equation(12) λOW=kbωγHS16αLOW, click here where λOW is the entrainment rate [s− 1], kb is the coefficient calculated from experiments [-], ω is the wave frequency [1 s− 1], γ is the white-capping dimensionless damping coefficient γ = 1E − 5ω(ρgHS/16)0.25 according to Hasselmann (1974) [-], HS is the significant wave height [m],

α is the dimensionless scaling factor [-] and LOW is the vertical length-scale parameter [m]. Adopting the values of 0.4 for kb ( Lamarre & Melville 1991) and 1.5 for α ( Delvigne & Sweeney 1988), and knowing the spatial averages of significant wave heights HS and wave spectra peak periods TP in the model domain, one can calculate and compare the time series of λOW and DD. Numerical modelling of wind wave generation in the entire Adriatic area for the period 1 January–15 November 2008 was carried out on the basis of the same wind field as applied in the model of sea circulation and oil transport (Lončar et al. 2010). The results were validated by comparison with wave-rider records (Lončar et al. 2010).