Does deep convection contain undiluted parcels?

Entrainment and detrainment rates are studied in cloud-resolving simulations of deep convection using passive tracers. In radiative-convective equilibrium, the rate at which undilute parcels mix with the environment is shown to have no dependence on their buoyancy. Instead, the flux of undilute parcels decays with height exponentially, indicating a constant probability per vertical distance of mixing with environmental air. Furthermore, this probability per distance is sufficiently large that there are effectively no undiluted parcels above a height of four kilometers. These results are shown to be independent of the horizontal grid size within the range of 3.2 kilometers to 200 meters.