The effect of grid resolution upon the numerical modelling of the convective boundary layer

A study has been made of the effects of varying the (uniform) grid resolution of a one-dimensional finite-difference numerical model of the dry convective boundary layer. The resolution of the inversion at the top of the boundary layer, and representation of the entrainment at the inversion, are found to influence the development of the momentum and buoyancy flux profiles. The modelled change in potential energy in a developing mixed layer is used to define a mixed layer scale, h _m, which is found to vary systematically with resolution. The discretization errors (which can be large for resolutions poorer than a few tens of metres, particularly in the early stages of mixed-layer development) are quantified.