10th International Aerosol Conference September 2 - September 7, 2018 America's Center Convention Complex St. Louis, Missouri, USA
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Aerosol Chemical Composition Measurements from a Ship Campaign across the Mediterranean and Middle East during the Summer of 2017
JAMES BROOKS, Eoghan Darbyshire, Frank Drewnick, Stephan Borrmann, Hugh Coe, University of Manchester
Abstract Number: 45 Working Group: Aerosol Chemistry
Abstract The Middle East is home to over 200 million people, with the majority living in urban areas. The climate is hot and arid, with climate warming significant especially in summer months. It is well known that this region suffers from intense dust concentrations, as well as other aerosol species. The Mediterranean basin is an area encompassing a variety of environments and climates, with the region susceptible to both long-range transport of atmospheric aerosol from Europe, Africa and the Middle East, as well as local sources such as ship emissions. Although the Middle East and Mediterranean regions are a global change hot spot, they have received only little attention, e.g., in reports of the Intergovernmental Panel on Climate Change (IPCC, 2013). One reason is that observational data are insufficient, unavailable or of limited quality. In the past, studies needed to rely on satellite observations and sparse meteorological data. Atmospheric chemistry data are essentially non-existent.
There is a key relationship between aerosol and atmospheric chemistry. The reactive uptake of pollutant gases by mineral compounds can drastically change the particle properties, whereas the aerosols in turn influence the gas phase chemistry. Acidic pollutants can turn the particles from hydrophobic into hydrophylic, and convert them into efficient cloud condensation nuclei (CCN) (Karydis et al., 2011). This can alter the microstructure of clouds and increase removal of the particulates by deposition processes (Abdelkader et al., 2016). These processes have been found to be of key importance for Saharan dust that is transported over the Mediterranean basin and Middle East region.
The Air Quality and climate change in the Arabian Basin (AQABA) study aims to alleviate current scientific issues with unique field measurements, combined with satellite observations and high resolution atmospheric chemistry and climate modelling. A comprehensive ship-borne campaign took place from June-September 2017 measuring gases and particles in the Arabian Basin and the Mediterranean, studying the regional contrasts that occur in the atmospheric pollutants. The results presented here are collected from an aerosol instrument called a High-Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-ToF-AMS), which collected aerosol chemical composition measurements. The presentation will summarise the key features in the regional aerosol burden for these regions, with an analysis into the sources of air masses.
Preliminary results show stark regional changes in aerosol chemical composition across the Middle East and the Mediterranean. Early highlights are very high sulphate and ammonia concentrations from a mix of local and long-transported sources in the Persian Gulf. Long range transported, highly oxidised organics in the Indian Ocean. Nucleation events in the Red Sea, coupled with high organics and sulphate concentrations throughout, especially in the Suez Canal region. And lastly, long range organics and nitrate concentrations in the Mediterranean, appearing to be sourced from mainland Europe.
References:
Abdelkader, M. et al., Chemical aging of atmospheric mineral dust during transatlantic transport. Atmos. Chem. Phys. Discuss., doi:10.5194/acp-2016-470, 2016.
IPCC, Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change (T.F. Stocker et al., eds.), Cambridge University Press, Cambridge, UK, and New York, NY, USA, 1535 pp, 2013.
Karydis, V.A. et al., On the effect of dust particles on global cloud condensation nuclei and cloud droplet number, J. Geophys. Res., 116, D23204, 2011.