Testing the EDMF Parameterization in the ARM Convective Diurnal Cycle Case

An integrated scheme for describing the dry and shallow cumulus boundary layer is here presented. The approach is based on the concept that in the convective boundary layer the main mechanisms of mixing are: local mixing that can be parameterised by an eddy-diffusivity scheme and non-local mixing performed by the mass-flux associated with thermals. This eddy-diffusivity/mass-flux scheme (EDMF) was implemented in the research model MesoNH (Lafore et al., 1996), taking advantage of the eddy-diffusivity closure based on the TKE budget equation to parameterise the local transport by smaller eddies. In the sub-cloud and in the cloud layers the mass-flux term represents the effect of strong updrafts. These are modelled by a simple entraining rising parcel, which determines the boundary layer height and, if present, the lifting condensation level and cloud top. The new scheme is tested against observations from the ARM dataset (Brown et al., 2002) corresponding to a diurnal cycle of a convective boundary layer with shallow cumulus development.