EQUILIBRIUM EVAPORATION BENEATH A GROWING CONVECTIVE BOUNDARY-LAYER

Expressions for the equilibrium surface Bowen ratio (beta(s)) and equilibrium evaporation are derived for a growing convective boundary layer (CBL) in terms of the Bowen ratio at the top of the mixed layer (beta(i)) and the entrainment parameter A(R). If A(R) is put equal to zero, the solution for beta(s) becomes-that previously obtained for the zero entrainment or 'closed box' model. The Priestley-Taylor parameter alpha is also calculated and plotted in terms of A(R) and beta(i). Realistic combinations of the atmospheric parameters give values of alpha in the range 1.1 to 1.4.