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Modelling the Deposition and Concentration of Long Range Air Pollutants: Final Report\ud

By Anthony Dore, Maciej Kryza, Stephen Hallsworth, Malgorzata Matejko, Jane Hall, Marcel Van Oijen, Ying Zhang, Bill Bealey, Massimo Vieno, Sim Tang, Ron Smith, Ulrike Dragosits and Mark Sutton


The FRAME Atmospheric Transport Model has been developed as a flexible multiple scale tool. The model can be applied to estimate the concentration and deposition of sulphur and nitrogen compounds at resolutions of 1 km and 5 km over the UK and at 50 km resolution over the EMEP European domain. The European simulation was used to generate the boundary conditions for the UK simulations.\ud The model demonstrated good agreement with measurements of aerosol concentrations (sulphate, nitrate and ammonium) and gas concentrations (SO2 and NO2) from the UK Eutrophying and Acidifying Pollutants monitoring network. Reasonable agreement was also obtained with wet deposition measurements. A greater scatter was apparent in the correlation with measurements of NH3 concentrations, due to the highly localised nature of their emissions.\ud The development of a fine scale (1 km resolution) version of FRAME over the UK represents an important step forward in improved spatial representation of concentrations and dry deposition of both oxidised and reduced nitrogen. Improvement in spatial disaggregation of ammonia emission sources and nature reserves at 1 km resolution was found to be highly significant in assessment of exceedance of the critical level for ammonia concentration at Special Areas of Conservation and Special Protection Areas.\ud The deposition of sulphur, oxidised nitrogen and reduced nitrogen in the UK is estimated to have decreased between 1990 and 2005 by 56%, 20% and 14% respectively. A strong inter-annual variability in sulphur and nitrogen deposition occurs due to changes in general circulation and precipitation which can result in fluctuations of annual deposition of +/- 10%.\ud The deposition of sulphur, oxidised nitrogen and reduced nitrogen in the UK is predicted to decrease between 2005 and 2020 by 47%, 32% and 16% respectively. Reduced nitrogen deposition will become relatively more significant than oxidised nitrogen and sulphur deposition. Policy to further reduce nitrogen deposition and acid deposition will need to focus on control of emissions of ammonia.\ud It was estimated that the total area of sensitive UK habitats exceeding the critical load will fall between 1970 to 2020 from 85% to 37% for acid deposition and from 73% to 49% for nutrient nitrogen deposition.\ud Emissions from international shipping currently contribute 18% and 19% respectively of the deposition of oxidised nitrogen and sulphur in the UK. With the implementation of Annex VI of the MARPOL convention, sulphur deposition from international shipping will be greatly reduced by 2020 whereas shipping emissions are likely to remain a significant source of nitrogen deposition.\ud A version of FRAME has been developed to include calculation of PM10 concentrations. A preliminary comparison with measurements from the UK monitoring network shows that concentrations are significantly under-estimated by the model. The reasons for this are thought to be due to missing chemical components (i.e. secondary organic aerosol and sea salts).\ud A web site has been maintained which gives a description of the FRAME model and illustrates the most recent deposition maps and correlation of model with measurements. The website can be found at:\u

Topics: Atmospheric Sciences
Publisher: NERC/Centre for Ecology & Hydrology
Year: 2009
OAI identifier:

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