A cumulus parameterization with multiple cloud base levels

We have generalized the Arakawa-Schubert cumulus parameterization to allow multiple cloud-base levels. A spectrum of cloud-top levels is allowed for each cloud-base level. We use a linear (rather than exponential) mass flux profile, because this greatly simplifies the determination of the entrainment rate and reduces the computational requirements of the parameterization. Cloud-top entrainment is included. The linear mass flux profile and the multiple cloud bases are separately tested in a general circulation model. Results show that the linear mass flux profile tends to lead to smoother precipitation distribution with a decrease in the depth and intensity of deep convection and that cumuli with cloud bases above the boundary layer tend to occur at night over land.