Evaluation of the drag coefficient for the Convective Boundary Layer

Suitable drag (C_D) and heat transfer (C_H) coefficients for bulk flow modelling of an inversion capped convective boundary layer are evaluated for different values of boundary layer thickness Y, ground roughness z₀ and Obukhov length L. On the basis of vertical velocity profiles proposed by Kader & Yaglom (1990) an implicit equation for C_D and C_H is derived. Data resulting from numerical solution are conveniently fitted by interpolating formulae relating the coefficients with the bulk Richardson number Ri_B and a nondimensional ground roughnes z₀/Y. Results are compared with previous formulations by other Authors.