2A Higher Order Closure Turbulence Model of the Planetary Boundary Layer

the requirements for the Degree of Master of Science A higher order closure turbulence model, using the full level 3 equations (Mellor and Yamada, 1974; Yamada and Mellor, 1975) is described in detail. A new formulation for the length scale, Z, which appears in each of the modeled terms, is employed. Equilibrium boundary conditions for the second moments are applied at the lower boundary. Day 33-34 of the Wangara experiment is simulated. Surface temperature and mixing ratio are predicted with a ground thermodynamics model. The effect of the inclusion of the Coriolis terms of the second moment equations on the results is evaluated and is found to be small. The similarity functions A, B, C, and D are evaluated. Vertically averaged variables are used in the deficit relations (Arya, 1977, 1978). With this formulation, the similarity functions C and D are found to be equal in the unstable boundary layer. In the stable boundary layer D appears to be smaller than C