School of Earth and Environment

AeroSol Cloud Interactions in UK Weather and Climate (ASCI project)

ASCI-UK is supported by the Met Office Academic Partnership with the University of Leeds, as a strategic priority for the partnership, and involves a commitment from the National Centre for Atmospheric Science (NCAS). The project aims to build, evaluate and use a new version of the UK Unified Model to address these pressing issues. The new model will be used to quantify the effects of aerosol-cloud-precipitation interactions on convective precipitation over the UK and the effects of past aerosol changes on the climate of UK convective precipitation.

The interaction of aerosols with clouds is known to significantly affect cloud dynamics and patterns of regional precipitation and intensity. The number and type of aerosol particles controls the number of cloud drops or ice crystals which are produced when clouds form. In turn, these affect the rate of precipitation, and its type. Finally, the heating and cooling generated by these cloud processes modifies the structure of a storm, and can affect the intensity of turbulence or surface winds.

There is now formal recognition by the Met Office that aerosol-cloud interactions could have far reaching implications for weather and climate prediction, and that Quantitative Precipitation Forecasting (QPF) could be improved by accounting for aerosol effects. However, aerosol-cloud interactions are very poorly handled in low resolution climate models and the processes are not included at all in operational Numerical Weather Prediction (NWP) models. Therefore the Met Office has a strategic goal to assess the impact of aerosol processes in its weather and climate models.

At the University of Leeds, we bring particular strength in the modelling of aerosol processes, through the GLOMAP and UKCA models, and a range of small-scale research models. We also have a strong track record in studying the science of cloud-aerosol interactions, with laboratory and field measurements.

A legacy of the partnership will be a step change in modelling capability, providing the UK with a new community model to address some of the greatest uncertainties in weather and climate prediction.

For more information on the ASCI project, contact John Marsham.