We derive the turbulent structure parameters of temperature (C2T and humidity (C2q ) from high-resolution large-eddy simulations (LES) of a homogeneously-heated convective boundary layer, driven by measurements at Cabauw (The Netherlands). Three different methods to obtain the structure parameters from LES are investigated. The shape of the vertical structure parameter profiles from all three methods compare well with former experimental results. Depending on the method, deviations in the magnitude up to a factor of two are found and traced back to effects of discretization and numerical dissipation of the advection scheme. Furthermore, we validate the LES data with airborne and large-aperature scintillometer (LAS) measurements at Cabauw. Virtual path measurements are used in order to study the variability of
C2T in the mixed and surface layer; and its implications for airborne and LAS measurements. A high variability of C2T along a given horizontal path in the LES data is associated with plumes (high values) and downdrafts (low values).
The given path average of C2T and thus the turbulence intensity along the path is varying rapidly in time. The LES results suggest that measured path averages require sucient temporal averaging and an adequate LAS setup inorder to obtain structure parameters which are representative for an entire horizontal area.