Modelling marine cloud brightening in large-eddy simulation and parcel model intercomparison projects

An understanding of aerosol-cloud interactions is key to many areas of climate science due to the diversity of mechanisms by which clouds interact with the Earth’s climate. One such area of growing interest is Climate Intervention – deliberately altering the climate to counteract anthropogenic Climate Change. Many Climate Intervention techniques concern aerosol-cloud interactions in some way, Marine Cloud Brightening (MCB) – whereby aerosols are injected into the marine boundary layer to increase the albedo of low clouds – does in particular. Developing a comprehensive understanding of MCB requires modelling across all scales. The focus of this work is modelling with large-eddy simulations (LES) and parcel models, performing a variety of experiments such as step forcing and continuous injection of aerosols in different models of the same class. Most the LES experiments have been performed in MONC (Met Office NERC Cloud) and compared to DALES (Dutch Atmospheric LES). Model intercomparison is key to understanding MCB; thus far there is disagreement among LES models over some important details of MCB, such the impact of small injected aerosols on the entrainment of dry air. It is hoped that better comparison of models can address this.