Seasonal influences on surface ozone variability in continental South Africa and implications for air quality
<p>Although elevated surface ozone (O<sub>3</sub>) concentrations are observed in many areas within southern Africa, few studies have investigated the regional atmospheric chemistry and dominant atmospheric processes driving surface O<sub>3</sub> formation in this re...
| Main Authors: | , , , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2018-10-01
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| Series: | Atmospheric Chemistry and Physics |
| Online Access: | https://www.atmos-chem-phys.net/18/15491/2018/acp-18-15491-2018.pdf |
| _version_ | 1818154027448270848 |
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| author | T. L. Laban P. G. van Zyl J. P. Beukes V. Vakkari K. Jaars N. Borduas-Dedekind M. Josipovic A. M. Thompson M. Kulmala L. Laakso |
| author_facet | T. L. Laban P. G. van Zyl J. P. Beukes V. Vakkari K. Jaars N. Borduas-Dedekind M. Josipovic A. M. Thompson M. Kulmala L. Laakso |
| author_sort | T. L. Laban |
| collection | DOAJ |
| description | <p>Although elevated surface ozone (O<sub>3</sub>)
concentrations are observed in many areas within southern Africa, few studies
have investigated the regional atmospheric chemistry and dominant atmospheric
processes driving surface O<sub>3</sub> formation in this region. Therefore, an
assessment of comprehensive continuous surface O<sub>3</sub> measurements performed
at four sites in continental South Africa was conducted. The regional O<sub>3</sub>
problem was evident, with O<sub>3</sub> concentrations regularly exceeding the
South African air quality standard limit, while O<sub>3</sub> levels were higher
compared to other background sites in the Southern Hemisphere. The temporal
O<sub>3</sub> patterns observed at the four sites resembled typical trends for
O<sub>3</sub> in continental South Africa, with O<sub>3</sub> concentrations peaking in
late winter and early spring. Increased O<sub>3</sub> concentrations in winter were
indicative of increased emissions of O<sub>3</sub> precursors from household
combustion and other low-level sources, while a spring maximum observed at
all the sites was attributed to increased regional biomass burning. Source
area maps of O<sub>3</sub> and CO indicated significantly higher O<sub>3</sub> and CO
concentrations associated with air masses passing over a region with
increased seasonal open biomass burning, which indicated CO associated with
open biomass burning as a major source of O<sub>3</sub> in continental South
Africa. A strong correlation between O<sub>3</sub> on CO was observed, while
O<sub>3</sub> levels remained relatively constant or decreased with increasing
NO<sub><i>x</i></sub>, which supports a VOC-limited regime. The instantaneous production
rate of O<sub>3</sub> calculated at Welgegund indicated that ∼ 40 %
of O<sub>3</sub> production occurred in the VOC-limited regime. The relationship
between O<sub>3</sub> and precursor species suggests that continental South Africa
can be considered VOC limited, which can be attributed to high anthropogenic
emissions of NO<sub><i>x</i></sub> in the interior of South Africa. The study indicated
that the most effective emission control strategy to reduce O<sub>3</sub> levels
in continental South Africa should be CO and VOC reduction, mainly associated
with household combustion and regional open biomass burning.</p> |
| first_indexed | 2024-12-11T14:19:59Z |
| format | Article |
| id | doaj.art-b8c33b7bfe32425896b6b9d4c395789e |
| institution | Directory Open Access Journal |
| issn | 1680-7316 1680-7324 |
| language | English |
| last_indexed | 2024-12-11T14:19:59Z |
| publishDate | 2018-10-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Atmospheric Chemistry and Physics |
| spelling | doaj.art-b8c33b7bfe32425896b6b9d4c395789e2022-12-22T01:02:58ZengCopernicus PublicationsAtmospheric Chemistry and Physics1680-73161680-73242018-10-0118154911551410.5194/acp-18-15491-2018Seasonal influences on surface ozone variability in continental South Africa and implications for air qualityT. L. Laban0P. G. van Zyl1J. P. Beukes2V. Vakkari3K. Jaars4N. Borduas-Dedekind5M. Josipovic6A. M. Thompson7M. Kulmala8L. Laakso9Unit for Environmental Sciences and Management, North-West University, Potchefstroom, South AfricaUnit for Environmental Sciences and Management, North-West University, Potchefstroom, South AfricaUnit for Environmental Sciences and Management, North-West University, Potchefstroom, South AfricaFinnish Meteorological Institute, Helsinki, FinlandUnit for Environmental Sciences and Management, North-West University, Potchefstroom, South AfricaDepartment of Environmental Systems Science, ETH Zürich, Zürich, SwitzerlandUnit for Environmental Sciences and Management, North-West University, Potchefstroom, South AfricaNASA/Goddard Space Flight Center, Greenbelt, Maryland, USADepartment of Physics, University of Helsinki, Helsinki, FinlandFinnish Meteorological Institute, Helsinki, Finland<p>Although elevated surface ozone (O<sub>3</sub>) concentrations are observed in many areas within southern Africa, few studies have investigated the regional atmospheric chemistry and dominant atmospheric processes driving surface O<sub>3</sub> formation in this region. Therefore, an assessment of comprehensive continuous surface O<sub>3</sub> measurements performed at four sites in continental South Africa was conducted. The regional O<sub>3</sub> problem was evident, with O<sub>3</sub> concentrations regularly exceeding the South African air quality standard limit, while O<sub>3</sub> levels were higher compared to other background sites in the Southern Hemisphere. The temporal O<sub>3</sub> patterns observed at the four sites resembled typical trends for O<sub>3</sub> in continental South Africa, with O<sub>3</sub> concentrations peaking in late winter and early spring. Increased O<sub>3</sub> concentrations in winter were indicative of increased emissions of O<sub>3</sub> precursors from household combustion and other low-level sources, while a spring maximum observed at all the sites was attributed to increased regional biomass burning. Source area maps of O<sub>3</sub> and CO indicated significantly higher O<sub>3</sub> and CO concentrations associated with air masses passing over a region with increased seasonal open biomass burning, which indicated CO associated with open biomass burning as a major source of O<sub>3</sub> in continental South Africa. A strong correlation between O<sub>3</sub> on CO was observed, while O<sub>3</sub> levels remained relatively constant or decreased with increasing NO<sub><i>x</i></sub>, which supports a VOC-limited regime. The instantaneous production rate of O<sub>3</sub> calculated at Welgegund indicated that ∼ 40 % of O<sub>3</sub> production occurred in the VOC-limited regime. The relationship between O<sub>3</sub> and precursor species suggests that continental South Africa can be considered VOC limited, which can be attributed to high anthropogenic emissions of NO<sub><i>x</i></sub> in the interior of South Africa. The study indicated that the most effective emission control strategy to reduce O<sub>3</sub> levels in continental South Africa should be CO and VOC reduction, mainly associated with household combustion and regional open biomass burning.</p>https://www.atmos-chem-phys.net/18/15491/2018/acp-18-15491-2018.pdf |
| spellingShingle | T. L. Laban P. G. van Zyl J. P. Beukes V. Vakkari K. Jaars N. Borduas-Dedekind M. Josipovic A. M. Thompson M. Kulmala L. Laakso Seasonal influences on surface ozone variability in continental South Africa and implications for air quality Atmospheric Chemistry and Physics |
| title | Seasonal influences on surface ozone variability in continental South Africa and implications for air quality |
| title_full | Seasonal influences on surface ozone variability in continental South Africa and implications for air quality |
| title_fullStr | Seasonal influences on surface ozone variability in continental South Africa and implications for air quality |
| title_full_unstemmed | Seasonal influences on surface ozone variability in continental South Africa and implications for air quality |
| title_short | Seasonal influences on surface ozone variability in continental South Africa and implications for air quality |
| title_sort | seasonal influences on surface ozone variability in continental south africa and implications for air quality |
| url | https://www.atmos-chem-phys.net/18/15491/2018/acp-18-15491-2018.pdf |
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