Annex I: Abstracts of posters An improved representation of the rain drop size distribution for single-moment microphysics schemes

We analyse observations of the size distribution of rain drops from a variety of cloud types and precipitation rates. The measurements show a transition from large rain drops observed in convective showers and frontal rainbands to higher concentrations of much smaller drizzle drops observed in stratocumulus clouds. The observations are used to develop an improved parameterization of the rain drop size distribution that better captures the observed transition for use in single-moment microphysics schemes. Sensitivity tests are performed in both climate and Numerical Weather Prediction versions of the Met Office Unified Model to demonstrate that the new parameterization leads to improvements in various precipitation and cloud related metrics.