The effect of ship tracks on cloud formation.

The study of aerosol cloud interactions is considered one of the priorities for the current climate research agenda. One of the standard forms of constraining these interactions in global climate models come in the form of ship track investigations. The formation of these thin and bright cloud patterns has been associated to the burning of bunker fuel by ships which releases large amounts of aerosol precursors into the atmosphere. The combination of pollutant particles and the surrounding water modifies the structure of marine clouds in such a way as to alter its reflectivity. This independent impact of ship emissions to cloud properties, can provide insights into the effects of large scale changes in aerosol concentrations on the climate. These cloud patterns however have been difficult to model and to detect in previous studies, mostly carried out using satellite retrievals.
From a fluid mechanics perspective, the formation of tracks may depend on the aerosol containing plumes from the ship being sufficiently buoyant (they have not been diluted enough by turbulent entrainment) upon reaching the top of the atmospheric boundary layer. Several processes related to meteorological factors or to the emissions themselves might affect the aerosol availability and distribution at the cloud. Hence these processes warrant further examination as to reduce the uncertainties in ship track investigations.
The aim of this project is to provide knowledge on how meteorological variability in the sub cloud layer affects the dispersion of pollutants, to identify the key mechanisms affecting droplet size distribution within the cloud layer, and finally to understand how everything links back to satellite retrieval data from ship track studies.

Research Questions
How does the ABL influence the aerosol availability at cloud base?
Is it possible to link the meteorological and emission quantities within the atmospheric layer directly to the cloud properties observed in satellite retrievals?
How effective are satellite retrievals in estimating droplet concentrations at the cloud top?

Relevant EPSRC themes include Engineering, Living with Environmental Change (LWEC).
Relevant EPSRC research areas include Fluid dynamics and aerodynamics, Numerical analysis, Particle technology.