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