During the BLLAST experiment a site composed of three large vegetation covers (moorland, maize field and forest) of about 1.5 km length and 500 m width was equipped to measure mean meteorological parameters and the surface energy balance terms. Surface characteristics, such as temperature, or humidity were also measured over the three adjacent patches. The surface layer above the moorland and the maize field was extensively probed by two tethered balloons, providing vertical profiles of temperature, humidity and wind. The atmosphere above was probed by two aircrafts measuring turbulence in the boundary layer during the late afternoon transition.
In a first step, the characteristics of the three surfaces are studied in terms of energy balance for a composite day gathering the eleven intensive observation periods. The type of soil being similar from one patch to another, the differences observed are mainly due to the vegetation cover. As expected, the forest is very different from corn and moor, but the corn appears to react as a vegetation cover at an intermediate position between moor and forest from many points of view (radiative component, ground storage, latent and sensible heat flux…).
The second step concerns the evolution of the turbulent kinetic energy from noon to the sunset. The turbulent kinetic energy decay over the three surface patches is compared and related to the surface characteristics. Such a comparison puts into question the use of a scaling law which will be discussed. Furthermore, thanks to surface and airborne measurements at different levels, the turbulent kinetic energy decay is considered simultaneously at the surface and in the whole boundary layer for different days of the BLLAST campaign.