Abstract: Proper parameterization of vertical turbulent fluxes is of fundamental importance in numerical simulation, not only at the ocean surface, but throughout the whole marine atmospheric boundary layer because exchange between the ocean and the atmosphere are mainly performed via turbulent mixing. In this study, a new parameterization for the eddy diffusivity coefficient to be used in a stratocumulus-topped boundary-layer model is proposed. The scheme is suitable when a fine resolution is used in the vertical, along with a coarse resolution in the horizontal that does not allow the boundary-layer structure to be explicitly resolved (e.g., as in mesoscale and large-scale models). The parameterization is obtained by fitting experimental data from large eddies investigated during the 2nd Aerosol Characterization Experiment (ACE2) to mixing length-based analytical formulas, using Taylor’s statistical theory of turbulence. The analytical formulae also allows the determination of the dissipation length from experimental data. Besides the turbulence parameterization, changes in the autoconversion scheme are carried out, in order to better represent the conversion of cloud water into rainwater (drizzle) in stratocumuli. Comparisons made through single-column model of real cases, observed during the ACE2, show good agreement between simulations and observed data of coupled and decoupled situations. A noticeable characteristic of such a scheme, since it uses a first order closure, is its low computational cost.