Structure of stable stratified boundary layers: study with of nonlocal turbulence model

Abstract

The structure of a planetary boundary layer depends on atmospheric stability (effects of buoyancy) and the dominating mechanism of turbulence generation [1]. The boundary layer becomes stably stratified when the underlying surface is colder than the air. In these conditions the turbulence can be generated by shear and destroyed under the influence of the negative buoyancy and viscosity. Because of the different action between shear and buoyancy effects, the turbulence in the stable boundary layer (SBL) is inhibited in comparison to the neutral and convective boundary layers (CBL). Until recently, to a problem of the observational studying and modeling of the SBL turbulence has not received much attention, despite its practical importance for the numerical forecast weather, air qualities in the urban areas (especially in the critical meteorological periods, early morning and evening rush hours with the greatest accumulation of air pollution). It can be related, first, to difficulties of the field and laboratory measurements arising from small scales of motion due to stratification. Secondly, with complexity in its dynamics caused by presence of intermittency, Kelvin-Helmholtz (K-H) instability, gravitational waves, low-level jets, meandering motions, etc. The evening and morning transitions from the convective case to the SBL and vice versa remain poorly understood and inadequately parameterized in models (e.g., [2-4]).