The structure of turbulence in a coastal atmospheric boundary layer

This study, based on airborne observations obtained during the Upper Spencer Gulf experiments in South Australia, investigates the structure of turbulence in a coastal boundary layer, which represents an extreme situation of horizontal inhomogeneity. The development of the coastal boundary layer under mainly onshore wind conditions, which is characterized by the formation of a convective thermal internal boundary layer (TIBL), is illustrated using cross‐sections of potential temperature, sensible‐heat fluxes and turbulent kinetic energy. The similarity of turbulence within the TIBL and the effectiveness of local scaling for inhomogeneous conditions are examined. It is suggested that, even in advective conditions, turbulence can be considered as being in local equilibrium. By introducing a simple TIBL model, local similarity relationships can be linked to external parameters. Some turbulence properties, such as the variance of vertical velocity, are found to be determined by three external parameters: the surface heat flux over land, the onshore wind speed and the thermal stability of the approaching airflow.