Preprints
https://doi.org/10.5194/egusphere-2023-1751
https://doi.org/10.5194/egusphere-2023-1751
06 Oct 2023
 | 06 Oct 2023

Measurement Report: Observations of Ground-Level Ozone Concentration Gradients Perpendicular to the Lake Ontario Shoreline 

Yao Yan Huang and D. James Donaldson

Abstract. Ground-level ozone (O3) is a secondary air pollutant that has harmful effects on human and ecosystem health. Close to larger bodies of water, the well-known sea- (or lake)-breeze phenomenon plays a role in regulating ground level ozone levels. An observed lake-edge removal effect, where ozone concentration decreases within the first 500 m to 1 km perpendicular to the lake, is thought to be related to the lake-breeze circulation as well as several dilution and removal pathways. A field campaign was conducted in summer 2022 and winter 2023 in two locations on the north shore of Lake Ontario: the urban centre of Toronto, and suburban Oshawa, some 50 km east, to assess how the local environment and season effects the lake-edge removal effect. Ozone, wind speed, and wind direction were measured on 6–7 different days in each season and city along transects perpendicular to Lake Ontario’s shoreline. A consistent negative linear relationship between ozone concentration and distance from shore over the first 500 m (i.e. a lake-edge removal effect) was observed in both cities and both seasons. The ozone gradient changed in Oshawa from -23.5 ± 8.5 (1 standard deviation) ppb/km in summer to -8.1 ± 5.1 ppb/km in winter. The slope remained consistent in Toronto at -15.4 ± 6.7 ppb/km in summer and -16.7 ± 7.3 ppb/km in winter. The year-round observation of an ozone gradient and lake-edge removal effect suggests that factors other than lake-breeze circulation, such as vegetation and titration by NO, have an influence on ozone levels at the lake-land boundary.

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Journal article(s) based on this preprint

26 Feb 2024
Measurement report: Observations of ground-level ozone concentration gradients perpendicular to the Lake Ontario shoreline
Yao Yan Huang and D. James Donaldson
Atmos. Chem. Phys., 24, 2387–2398, https://doi.org/10.5194/acp-24-2387-2024,https://doi.org/10.5194/acp-24-2387-2024, 2024
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The requested preprint has a corresponding peer-reviewed final revised paper. You are encouraged to refer to the final revised version.

Short summary
Ground-level ozone interacts at the lake-land boundary; this is important to our understanding...
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