A HYBRID TURBULENCE MODEL FOR SIMULATING THE DYNAMICS OF THE MARINE CLOUD LAYERS

摘要

Goals of the atmospheric research at the University of the District of Columbia (UDC) are to identify physical processes that determine the dynamics of the marine cloud layers and to quantify the roles of turbulence, convection and thermal radiation that play in formation, dissipation and stability of the cloud layers. Our immediate objectives are to advance theoretical models, use efficient numerical schemes and develop computer programs to simulate the marine cloud layers. For these objectives two turbulence models, using the second-order-closure and the large-eddy-simulation (LES) models, respectively, were firstly formulated. In order to retain details of the second-order turbulence and calculation efficiencies of the LES model, a hybrid turbulence model has been assembled and it is presented in this paper. The model uses a multidimensional framework of the LES model but uses a set of unidirectional second-order equations to calculate the turbulent intensity values. Results of predicted cloud profiles using the hybrid model are compared with experimental data and predictions using the LES.