[ABS] 73 - H.F. de Campos Velho, A. B. Nunes, P. Satyamurty, G.A. Degrazia, A.G. Goulart, U. Rizza (2007): Evaluation of a Theoretical Model for a Growing Convective Boundary Layer by Large Eddy Simulation, Meteorology and Atmospheric Physics (submitted).

Abstract: The planetary boundary layer (PBL) presents different characteristics during the diurnal cycle: convective (turbulence produced mainly due to heat flux from the Earth’s surface to the atmosphere), stable (a balance between mechanical turbulence production and thermal energy from the atmosphere to the soil), and the neutral condition (turbulence generated from the wind shear). There are fewer studies about the transition layers: residual boundary layer and growing convective boundary layer (Growing-CBL) – the last one is still less discussed. The objective of the present paper is to present a theoretical model for the latter transition PBL. A spectral model is developed from the solution of the evolution of the turbulent kinetic energy equation using the Heisenberg’s hypothesis. Such a model for the growth of the convective boundary layer is evaluated against results from Large Eddy Simulation (LES). The three-dimensional (3D) turbulent spectrum is obtained from a conversion of the one-dimensional (1D) wind spectra. The time evolution for this analytical 3D spectrum is computed taking into account the increasing of the surface heat flux. The changes in the turbulent kinetic energy (TKE) are compared with the results obtained from LES (for three vertical levels). The reliability of analytical model presented here is proved through the physical consistency verified in the spectral behavior of the growing-CBL and by the good agreement between the integrated TKE of the two models.