Also, simply increasing the grid resolution will not allow inclusion of street canyon processes which delay the mixing of pollutants into the wider atmosphere and allow a greater degree of processing at elevated concentrations. Consequently, there is a need for custom-built chemistry-transport models, carefully designed to simulate the urban atmosphere, rather than downscaling of large domain models by increased grid resolution.
This needs to be accompanied by higher resolution physical and chemical measurements, so as to maximise the value of such models. Conventional knowledge of global and regional atmospheric chemistry is not sufficient to predict the behaviour of pollutants in the urban atmosphere. As model resolution is progressively improving, large domain models will increasingly be able to better resolve the urban atmosphere but will need to reflect the differing pollution climate and physical properties of the urban atmosphere in order to make reliable predictions.
There is a pressing need for reliable estimates of pollutant concentrations and spatial distributions for use in epidemiological studies, but the widespread use of land-use regression modelling techniques 24 in preference to Chemistry-Transport Models CTMs may be a reflection of the poor predictive capability of CTMs in urban areas, which in part reflects weaknesses in their dynamics and chemistry schemes. There is a need to tackle this problem by building new models incorporating specifically urban forms and processes, as opposed to continual downscaling of coarse resolution rural models.
While there remains a substantial overlap between processes occurring in large scale atmospheric processes and those on the smaller urban scale, the differences are sufficient to justify regarding urban atmospheric science as a very special case which cannot be addressed reliably by a simple downscaling of larger scale processes. It is a welcome development that the recent National Academies report on Tropospheric Chemistry 25 gives an acknowledgement of the importance of urban processes, but unfortunately it fails to give adequate emphasis to the special character of urban processes.
Baklanov, A. Bohnenstengel, S. Meteorology, air quality, and health in London: the ClearfLo project. Ryerson, T. The California research at the Nexus of air quality and climate change CalNex field study. Chapman, L. The birmingham urban climate laboratory. An open meteorological test bed and challenges of the Smart City. Charron, A. Grawe, D. Large eddy simulation of shading effects on NO2 and O3 concentrations with an idealised street canyon. Harrison, R. Heard, D. High levels of the hydroxyl radical in the winter urban troposphere. Atkinson, R.
OH radical production from the gas-phase reactions of O3 with a series of alkenes under atmospheric conditions. Stockwell, W. The second generation regional acid deposition model chemical mechanism for regional air quality modeling. Tropospheric cycle of nitrous acid. Thunis, P. Analysis of model responses to emission-reduction scenarios within the CityDelta project. Vautard, R. Evaluation and intercomparison of ozone and PM10 simulations by several chemistry transport models over four European cities within the CityDelta project.
Evaporation of traffic-generated nanoparticles during advection from source. Reche, C.
Urban NH3 levels and sources in a Mediterranean environment. Real time chemical characterization of local and regional nitrate aerosols. Crilley, L.
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On the interpretation of in situ HONO observations via photochemical steady state. Faraday Discuss. Remarkable dynamics of nanoparticles in the urban atmosphere. Alam, M. The characterisation of diesel exhaust particles—composition, size distribution and partitioning. On the spatial distribution and evolution of ultrafine particles in Barcelona.
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On the formation, growth and composition of nucleation mode particles. Tellus 53B , — Hoek, G. A review of land-use regression models to assess spatial vriaton of outdoor air pollution. Cheng, W. Computational formulation for the evaluation of street canyon ventilation and pollutant removal performance. Seinfeld, J.
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Subjects Environmental chemistry. Abstract Studies of the chemistry of the urban atmosphere provide special challenges which arise from the high density of emissions, strong concentration gradients and relatively high pollutant concentrations. Introduction By far the main emphasis of research in past decades in atmospheric chemistry has been on the global and regional atmosphere.
What distinguishes urban areas from regional processes? The main features characterising air pollution phenomena in urban areas which distinguish them from regional processes include the following: High levels of primary emissions. Table 1 Spatial and temporal scales of some UK cities Full size table.
Evaluated Kinetic Data
Table 2 Lifetimes with respect to reaction with OH Full size table. Schematic profile of traffic-generated pollution across a city. Full size image. Table 3 Average concentrations annual mean at roadside and urban background sites in London, and in the rural background Full size table. Table 4 Lifetimes with respect to dry deposition for particles of various sizes as a function of mixing layer depth Full size table.
Table 5 Residence times in street canyons Full size table. Consequences of urban atmospheric properties The points raised above lead to a number of conclusions: It matters critically where you measure in the horizontal and the vertical. Conclusions Conventional knowledge of global and regional atmospheric chemistry is not sufficient to predict the behaviour of pollutants in the urban atmosphere. References 1. Article Google Scholar 2. Article Google Scholar 3. Article Google Scholar 5. Article Google Scholar 7.
Article Google Scholar 8. Article Google Scholar 9. Article Google Scholar Google Scholar Google Scholar Download references. Harrison Authors Search for Roy M. Ethics declarations Competing interests The author declares no competing financial interests. Additional information Publisher's note: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Because the stratosphere is relatively isolated from the layers of the atmosphere above and below it, once chlorine-containing species enter the stratosphere, they remain there for long periods of time. Each chlorine atom produced from a CFC molecule can lead to the destruction of large numbers of ozone molecules, thereby decreasing the concentration of ozone in the stratosphere.
Eventually, however, the chlorine atom reacts with a water molecule to form hydrochloric acid, which is carried back into the troposphere and then washed out of the atmosphere in rainfall. Massive ozone depletions were first observed in over the Antarctic and more recently over the Arctic. Although the reactions in Equation 3.
3.6 Chemical Reactions in the Atmosphere
At high latitudes near the poles , therefore, a different set of reactions must be responsible for the depletion. Recent research has shown that, in the absence of oxygen atoms, chlorine monoxide can react with stratospheric nitrogen dioxide in a redox reaction to form chlorine nitrate ClONO 2.
When chlorine nitrate is in the presence of trace amounts of HCl or adsorbed on ice particles in stratospheric clouds, additional redox reactions can occur in which chlorine nitrate produces Cl 2 or HOCl hypochlorous acid :. Both Cl 2 and HOCl undergo cleavage reactions by even weak sunlight to give reactive chlorine atoms. When the sun finally rises after the long polar night, relatively large amounts of Cl 2 and HOCl are present and rapidly generate high levels of chlorine atoms.
The reactions shown in Equation 3.