The turbulence structure of the cloudy marine boundary layer has been investigated using aircraft measurements taken during the first Lagrangian period of the Atlantic Stratocumulus Transition Experiment. In particular, the study focuses on determining the properties of the turbulent transfer when the cloud layer is decoupled from the subcloud layer. A new turbulence parameterization based on a system of second-moment equations has been developed and applied to cases of both well-mixed and decoupled cloudy marine atmospheric boundary layers. A recently developed method of estimating nonlocal mixing within the boundary layer utilizes this developed turbulence parameterization and determines the probability of mixing occurring among different parcels. The method is tested on a case with an inhomogeneous boundary layer. A way of implementing the method in an algorithm for a mesoscale model will be presented. This approach is based on nudging model results with a nonlocal contribution with respect to the equilibrium time scale required for complete nonlocal mixing. The equilibrium time scale is determined from the frequency of the peak of the power spectrum of the vertical velocity variance by using aircraft measurements