Recent studies have revealed that the weather patterns strongly influence the nature of pollutant particulates in the air.
NCAS and University of Manchester scientists studied archived data to assess the role of season and weather on the amounts and chemical composition of particulates in Manchester city centre, as part of a study supported by the Sustainable Consumption Institute (SCI). This is the first long term study of detailed particulate composition in the UK.
‘It is well known that the effect of season and meteorology on air pollution in Manchester city centre are closely linked, with the meteorology playing major controlling role’ comments scientist James Allan, ‘however this study was also able to probe the chemical composition of the changing pollution.'
The data was collected using methods for measuring particulates that give very detailed information regarding the mass (size and weight) and composition of the particulates. These methods are normally confined to laboratory settings or restricted to short periods.
There have been a number of these short periods of intensive particle measurements in central Manchester between 2001 and 2007. In total, 105 days of measurements of particulates in the city have been collected together to for the first time. This multi-year study is the first of its kind.
Collating the data allowed the scientists to study the chemical composition and reveal the seasonal and meteorological trends over many years.
The scientists saw that the elevated particulate concentrations during wintertime inversion conditions were mainly primary organic matter and nitrates, whereas the events during the summer were mainly in the form of sulphates and secondary organic matter, some of which are from sources outside of Manchester.
Dr Allan and colleagues at the University of Manchester traced the sources of the particulates to outside of Manchester using a computer model to calculate back-trajectories. In the computer model, the path of the air is followed backwards in time to discover its route towards the measurement site. They found five common directions that the air came from. Air from certain directions, where there were more pollution sources upwind, had higher concentrations of particles.
Changing weather patterns as a result of climate change make this research applicable for application in a future climate. Air quality forecasting in a changing climate is a significant challenge.
Seasonal variation of fine particulate composition in the centre of a UK city. C.L. Martin, J.D. Allan, J. Crosier, T.W. Choularton, H. Coe and M.W. Gallagher. Atmospheric Environment 45, Issue 26, August 2011, Pages 4379-4389
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Notes to editors
What is NCAS
The National Centre for Atmospheric Science (NCAS) is a world leader in atmospheric science with an annual budget of £19 million. NCAS carries out research programmes in climate science, atmospheric composition (including air quality) , weather (including hazardous weather) and state-of-the-art technologies for observing and modelling the atmosphere (including a world-leading research aircraft). We have over 170 research scientists, including UK and world experts to work on our research programmes, and provide support to the academic community. These programmes are distributed throughout the UK, at about 20 UK universities and institutes. NCAS is a research centre of the Natural Environment Research Council with its headquarters at the University of Leeds. Further information can be found at www.ncas.ac.uk