Resolution dependence of the diurnal cycle of precipitation simulated by a global cloud-system resolving model

Abstract

Resolution dependence was found in the simulated diurnal precipitation cycle over land in the tropics. We conducted a series of grid refinement experiments of the atmosphere from 14 km to 0.87 km using a global high-resolution model without any convection parameterizations. In the high-resolution experiment, the peak of the cycle was earlier and precipitation at the peak was higher. The characteristics of the simulated diurnal precipitation cycle changed at a grid spacing of around 2-3 km. The precipitation started to increase in the morning in the high-resolution experiments, suggesting that small-scale moist convection became active in the late morning. In the lower-resolution experiments, convection and precipitation began in the late afternoon. As well as the enhancement of moisture transport from the boundary layer to the middle troposphere, the rapid formation of rain can also be attributed to the difference in diurnal precipitation cycles between lower and higher resolution experiments.