Atmospheric Controls on the Development of Shallow Convective Clouds in Large Eddy Simulations

This thesis makes use of a new atmospheric community model MONC (the Met Office and NERC Cloud Model) to explore atmospheric controls on the development of shallow, non-precipitating convective clouds. Simulations presented here are initialised using profiles based on those observed during the COPE (COnvective Precipitation Experiment) field campaign in 2013. Isolated convective clouds are generated using heterogeneous surface fluxes, which act upon a turbulent convective boundary layer (CBL). The CBL is capped by an inversion, above which the environment is statically stable. A cloud tracking algorithm is used to track and study individual clouds, including those which split and merge over time. The role of sub-cloud variability (produced during turbulent model spinup) on convective cloud development is explored, and is concluded to play a significant role in modulating cloud vertical transport, both through determination of properties at cloud base and through different rates of turbulent entrainment along the edge of the cloud. Gravity waves develop during these simulations, propagating in all directions, and are shown to produce large-scale environmental subsidence with comparable magnitude to that generated by localised subsiding cloud shells enveloping the core, as well as influencing the regeneration of individual clouds.