Keywords: friction velocity, mixing height, Monin-, Obukhov length, roughness length, PBL height, sensible heat flux, planetary boundary layer, turbulence, boundary layer depth
Boundary layer depth: sensitivity study
The planetary boundary layer (PBL) height calculation is a two-step process. In the first one, the turbulence characteristics are evaluated either from direct measurements or through parameterisation schemes that use indirect measurements. In the second one, the PBL height is calculated using a model. For the convective PBL, simple models consider two parameters: the height and the temperature jump of the elevated inversion. The solution of two differential equations that couple those two parameters to the atmospheric turbulence properties gives the time evolution of the PBL height. For the stable case, simpler expressions are used; they relate the height of the PBL to the mechanical turbulence parameter u*. The results of different methods of evaluating the more significant turbulence parameters for the PBL height calculation are analysed and compared.