Numerical experiments with a one-dimensional higher order turbulence model: Simulation of the Wangara Day 33 case

A one-dimensional stratocumulus model is developed and incorporated into a cloud/mesoscale model to simulate the evolution of the marine stratocumulus-capped mixed layer. This paper describes the formulation of the higher-order turbulence model. In a companion paper (Chen and Cotton, 1983), the formulation of the atmospheric radiation model, the partial condensation and the cloud fractional parameterization are described. The second-order moments of this model are partially diagnosed. In order to close the system, the parameterization for the third-order moments given by Zeman and Lumley (1976) is adopted and is generalized to include total water and cloud water. A new scheme to parameterize the skewness terms is proposed in order to satisfy the enforced realizability. Those skewness terms are used to close the third-order moments. In this paper, experiments are carried out to test the turbulence model by using the Wangara Day 33 data, which represents a ‘dry’ case study. Sensitivity experiments using the turbulence length scale parameterizations formulated by Andréet al. (1978) and Sun and Ogura (1980) are reformed and are compared.