The energy- and flux budget theory for surface layers in atmospheric convective and stably stratified turbulence

TL;DR

This paper develops an energy- and flux budget (EFB) turbulence closure theory for atmospheric surface layers, capturing complex turbulence behaviors in convective and stably stratified conditions, with potential modeling applications.

Contribution

The paper introduces a novel EFB turbulence closure theory that models turbulence in atmospheric surface layers considering both convective and stratified regimes.

Findings

Derived relationships for turbulence characteristics in surface layers.

Profiles for TKE, fluxes, and anisotropy are provided.

The theory captures the transition between shear-driven and buoyancy-driven turbulence.

Abstract

The energy- and flux budget (EFB) turbulence closure theory for the atmospheric surface layers in convective and stably stratified turbulence has been developed using budget equations for turbulent energies and fluxes in the Boussinesq approximation. In the lower part of the surface layer in the atmospheric convective boundary layer (CBL), the rate of turbulence production of the turbulent kinetic energy (TKE) caused by the mean-flow surface shear and the shear of self-organised coherent structures is much larger than that caused by the buoyancy, which results in three-dimensional turbulence of very complex nature. In the upper part of the surface layer, the rate of turbulence production of TKE due to the shear is much smaller than that caused by the buoyancy, which causes unusual strongly anisotropic buoyancy-driven turbulence. Considering the applications of the obtained results to the atmospheric convective and stably stratified boundary-layer turbulence, the theoretical relationships potentially useful in modelling applications have been derived. In particular, the developed theory for the surface layers in turbulent convection and stably stratified turbulence allows us to determine the vertical profiles for all turbulent characteristics, including TKE, the intensity of turbulent potential temperature fluctuations, the vertical turbulent fluxes of momentum and buoyancy (proportional to potential temperature), the integral turbulence scale, the turbulence anisotropy, the turbulent Prandtl number and the flux Richardson number.