A revolutionary new Lagrangian model for convective clouds

This project will contribute to the development of a revolutionary new cloud model, MPIC (Moist Parcel-In-Cell), for the simulation of convective precipitation and cloud-climate feedbacks. The model takes a new, Lagrangian approach to the simulation of clouds and precipitation. The work builds on a collaboration between David Dritschel (University of St Andrews), EPCC, Leeds and the Met Office and involves comparison to the Met Office’s CASIM (Cloud AeroSol Interactions Microphysics) scheme.

The behaviour of turbulence and microphysical processes largely determines the timing and intensity of precipitation in weather and climate models. These processes also determine cloud properties which are important to climate change, but remain difficult to model even at high resolution. Droplets and hydrometeors interact to form precipitation along Lagrangian flow trajectories (small particles) or fall trajectories (larger particles, influenced by the ambient wind). MPIC deals with the dynamics of clouds by advecting parcels of fluid. Here, we propose to use MPIC to study precipitation in realistic clouds, such as those observed in the recent EUREC4A field campaign in Barbados. Applying the parcel-based approach to cloud droplets and extending it to rain will make accurate  simulation of regions in the cloud where rain forms possible.