Questions involving the use of traditional convection parameterization in NWP models with a higher resolution

Traditional schemes for parameterization of convection have mainly been developed and tested for models with horizontal resolution of the order of 100 km. Experiments are undertaken to test the behaviour of a traditional parameterization scheme for convection, designed for a coarse resolution, in a numerical weather prediction model when the model resolution is increased. It is shown that a more detailed forecast of convective precipitation and cloudiness is possible with the finer resolution and that the reason for this is a better simulation of the mesoscale circulation and therefore areas with convergence of moisture, necessary for moist convection to take place. The convergence of moisture is included in the closure assumption for the parameterization scheme and the importance of the formulation of the closure is therefore studied.