Spatial organisation affects the pathway to precipitation in simulated trade-wind convection

We investigate whether and how spatial organisation affects the pathway to precipitation in realistic large-domain large-eddy simulations of the North Atlantic trades. We decompose the formation of surface precipitation (P) into a production phase, where cloud condensate is converted into rain, and a sedimentation phase, where rain falls towards the ground while some of it evaporates. With strengthened organisation, rain forms in weaker updrafts from smaller mean cloud droplets so that cloud condensate is less efficiently converted into rain. At the same time, organisation creates a locally moister environment and modulates the microphysical conversion processes shaping rain properties. This acts to reduce evaporation so that more of the produced rain reaches the ground. Organisation thus affects how the two phases contribute to P. It only weakly affects the total precipitation efficiency. We conclude that the pathway to precipitation differs with spatial organisation and suggest that organisation buffers rain development.