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We utilise a range of instruments flown on board the FAAM BAe146 research aircraft. These include probes able to count and size cloud droplets, raindrops, ice crystals and snowflakes. We also use instrumentation to measure bulk liquid and ice water contents, to sample the physical and chemical characteristics of atmospheric aerosol particles and to measure the dynamical and thermodynamical characteristics of the air.

An important interest is stratocumulus cloud within the atmospheric boundary layer. This is maintained by a near-balance of physical processes including radiation, turbulent transport of heat and moisture and microphysics. The correct representation of interactions between these various processes is very important in forecasting the formation, variability and break-up of stratocumulus. We are currently using field observations to compare with forecasts of the cloud made with the Unified Model.

We also study the formation and evolution of ice within clouds. This can have a significant impact on the evolution of precipitation from cloud systems around the UK. Below 0C, ice can grow more quickly than liquid cloud droplets due to the lower saturation vapour pressure over an ice surface. We are developing an ice nucleus (IN) counter to detect the aerosol particles involved in the initiation of ice in the mid-troposphere.

Key Aims

• Improved understanding of microphysical processes in cloud and precipitation systems.
• Use of high-resolution numerical models to assist in the interpretation of field observations.
• Guidance on the development of improved parametrization schemes for microphysical processes in the Unified Model.
• Development of improved observational techniques to study microphysical processes.

Current projects

• VOCALS-REx This was a large field project that took place in Oct/Nov 2008. It involved research aircraft and ships in a major study of physical processes in the stratocumulus forming off the coast of Peru and Chile.
• CONSTRAIN - a UK-based campaign to study microphysical process in ice and mixed-phase cloud layers. The aircraft was based at Prestwick in Scotland for 3 weeks.
• COALESC - a campaign to study stratocumulus around the UK in Feb/Mar 2011. It also involved ground-based observations by the Meteorological Research Unit.