Study of second-order turbulence closure technique and its application to atmospheric flows

Abstract

The applicability of the second-order turbulence closure technique to atmospheric mesoscale flows is investigated. Analytical and numerical studies of various closure schemes are performed. Theoretical investigations of the well-known Mellor and Yamada approach result in new realizability conditions for the Level 2.5 and Level 3.0 schemes. The bulk parameters (eddy exchange coefficients) are calculated from the full second order closure model. The comparison of these parameters with the experimental data reveals that the simple Richardson number-based scaling is not adequate. The Level 2.5 and Level 4.0 models are developed and applied to a California stratocumulus case. The new realizability conditions are applied in the Level 2.5 model. The results are presented and show good agreement with experimental data collected off the California shoreline. On the basis of these studies, conclusions about applicability of simplified second-order turbulence closure technique are formulated.