The distribution of aerosol and trace gases in the lower troposphere over South Africa
| dc.contributor.author | Burger, Roelof Petrus | |
| dc.date.accessioned | 2017-01-20T12:35:17Z | |
| dc.date.available | 2017-01-20T12:35:17Z | |
| dc.date.issued | 2016 | |
| dc.description | A thesis submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Doctor of Philosophy. September 2016. | en_ZA |
| dc.description.abstract | Numerous studies on the sources, transport and fates of criteria air pollutants and greenhouse gases have been done in southern Africa. However, debate on the priority pollutants and areas of concern continue despite a growing national air quality monitoring network. This study attempts a novel approach to characterise sources and ambient air quality over major industrial and urban areas using a single suite of instrumentation to provide information to improve management of air quality. Over 200 hours of data were collected from an airborne platform. Another 5 ground-based campaigns characterised sources and areas out of reach of the aircraft. The central aim of this study is to prioritise sources and areas of concern with regards to air quality management, using a mobile platform. This complements other modelling and spatial assessments and provides in situ validation for many contemporary debates. The specific aims were to characterise major anthropogenic sources; estimate the state of air quality; investigate the vertical distribution of pollutants; and prioritise sources and areas of concern for effective air quality management in South Africa. The research has delivered many original contributions to the body of knowledge of air quality over South Africa. These findings can be divided into spatial and temporal relationships between sources and receptors, characterising source contributions and understanding the contribution of atmospheric emissions. High resolution measurements show that spatial scales of prominent atmospheric plumes are much smaller than current remote sensing estimates.This underscores the difficulty of accurately assessing environments with diverse, clustered sources and complex meteorology through modelling studies and satellite based remote sensing. The current conceptual model of absolute stable layers is biased because of limited data availability where a limited number of levels are reported. At least 60 levels should be reported in soundings to study absolutely stable layers. The inclusion of the standard reporting levels, (850 hPa, 700 hPa, 500 hPa and 300 hPa), further biases the detection of atmospheric stable layers. The number of observed persistent levels change in number and character when these are omitted from the analysis. Numerous vertical profiles further show that the thermodynamic model of stability as the main driver of stratification is oversimplified, especially close to source regions where different pollutants are observed to peak at different levels unrelated to absolutely stable layers. This suggests that the original buoyancy which is governed by the release temperature, exit velocity and height are important drivers for the stratification of pollutants. The overall conclusion is made that a small team with a set of regular instrumentation can prioritise pollutants and areas of concern on a national scale. This method could be valuable for countries with limited resources and infrastructures and could be used in combination with modelling and satellite based remote sensing to assess priorities. The ability to obtain in situ data of a large number of variables over vast areas in a short time may offsets the caveats associated with mobile measurements and a limited sample volume. | en_ZA |
| dc.description.librarian | LG2017 | en_ZA |
| dc.format.extent | Online resource (463 pages) | |
| dc.identifier.citation | Burger, Roelof Petrus (2016) The distribution of aerosol and trace gases in the lower troposphere over South Africa, University of Witwatersrand, Johannesburg, <http://wiredspace.wits.ac.za/handle/10539/21740> | |
| dc.identifier.uri | http://hdl.handle.net/10539/21740 | |
| dc.language.iso | en | en_ZA |
| dc.subject.lcsh | Air--Pollution--Measurement | |
| dc.subject.lcsh | Aerosols | |
| dc.title | The distribution of aerosol and trace gases in the lower troposphere over South Africa | en_ZA |
| dc.type | Thesis | en_ZA |
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