Vertical Profiles of Turbulence Parameters in the Thermal Internal Boundary Layer

Abstract

The correct simulation of pollutant dispersion in coastal regions demands understanding the turbulence structure of the thermal internal boundary layer (TIBL), which typically occurs in daytime when maritime air is advected over the continent. Such a structure is investigated using 10 levels of turbulence observations made at a 140-m micrometeorological mast installed at 3500 m from the shoreline in south-eastern Brazil, with TIBL dimensionless vertical profiles of the turbulence parameters commonly used in Lagrangian and Eulerian dispersion models determined. To accomplish that, the TIBL height $$z_i$$ is estimated using a vertical-flux-convergence approach, developed here. The values experimentally obtained for $$z_i$$ agree with those predicted by a widely-used model for TIBL growth. In general, the normalized turbulent profiles evaluated for the TIBL differ from those previously obtained in the convective boundary layer (CBL). The horizontal eddy diffusivities evaluated for the TIBL are larger than those typically observed in the CBL, while the vertical ones are similar for both boundary layers. Finally, it is shown that CBL similarity relationships can be used to describe turbulent parameters as long as the proper empirical constants are used.