Vertical heat flux in the convective boundary layer

The variation of heat flux with height in inversion-capped convective boundary layers is discussed. Cospectral shapes at levels above approximately one-tenth the height of the lowest inversion base (z1) are shown to depart significantly from surface layer forms. the characteristic wavelength for heat flux increases rapidly in the first 150 m of the boundary layer but shows little variation between 150 and 300 metres. Around sunset, the transition to negative heat flux occurs first in the upper regions of the boundary layer and propagates downwards to the surface.