Effect of convective entrainment/detrainment on simulation of tropical precipitation diurnal cycle: A regional model sensitivity study

A regional climate model is used to investigate the effect of convective entrainment/detrainment on the simulated the diurnal cycle of tropical precipitation over the Maritime Continents and the surrounding oceans. In a control experiment with the default convective entrainment/detrainment rates, the model simulated too early mature convective precipitation with too large amplitude over the Maritime Continents. In two sensitivity experiments with the entrainment/detrainment rates increased for deep and shallow convection, respectively, the diurnal phase of precipitation is delayed by 1-2 hours with reduced diurnal amplitude over the Maritime Continents. The simulated diurnal cycle is more realistic with enhanced entrainment/detrainment rates for shallow convection compared to recent satellite observations. In particular, the model simulated realistically offshore migration of the diurnal signal forced by deep convection over the Maritime Continents. With the improved diurnal characteristics, the model also simulated more realistic fraction of large-scale precipitation with increased temporal variability.