Some features of the ozone climatology of Ontario, Canada and possible contributions of stratospheric ozone to surface concentrations

Mukammal, E. I.; Neuman, H. H.; Nichols, T.R.

doi:10.1007/bf02277447

Cited by 15 publications

(4 citation statements)

References 18 publications

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“…Numerous hours and days with O 3 concentrations greater than 82 ppb were experienced throughout southwestern Ontario, with stations along the shores of lakes Erie and Huron recording the highest numbers. This is likely a result of O 3 -rich plumes moving across the lakes and downward mixing at the lake shores 12 (Mukammal et al 1985). Stations in central Ontario showed fewer hours and days with O 3 concentrations greater than 82 ppb, although sites within and close to Toronto showed an elevation in the number of hours and days (Figure 7).…”

Section: Hours and Days Exceeding The Maximum Acceptable Ozone Objective Of 82 Ppbmentioning

confidence: 99%

Ground-Level Ozone in Eastern Canada: Seasonal Variations, Trends, and Occurrences of High Concentrations

Fuentes

Dann²

1994

Air & Waste

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Over the past few years, concern has increased in Canada over the health and environmental impacts of elevated concentrations of ground-level ozone. During the summer the most populated regions of Canada frequently record ozone concentrations that exceed the one-hour average maximum acceptable air quality objective of 32 parts per billion (ppb). In 1988 the Canadian Council of Ministers of the Environment agreed to develop a federal/provincial management plan to control nitrogen oxide and volatile organic compound emissions to reduce ozone concentrations in all affected regions of the country. In addition to the proposed interim control measures, the plan recommended that studies be undertaken to acquire the information necessary to develop sound control strategies. This report represents one of those studies and provides a summary of ground-level ozone measurements for eastern Canada for the 1980 to 1991 period with an emphasis on seasonal variations, trends, and occurrences of high concentrations.Southwestern Ontario experiences the highest maximum hourly ozone concentrations and the greatest frequency of hours greater than the 82 ppb acceptable objective. Urban sites have the highest frequencies of ozone concentration measurements in the < 10 ppb range, while rural and remote sites show peaks in frequency distribution in the 20 to 30 ppb range. Trend analysis of summertime (May to September) average daily maximum ozone concentration showed no consistent pattern for eastern Canadian sites during 1980 to 1991. Sites in Montreal showed statistically insignificant downward trends while sites in Toronto showed small but statistically significant upward trends. These ozone-increasing trends are associated with reductions in nitric oxide concentrations. At all sites there was large year-to-year variability in peak ozone levels and in the frequency of hours with ozone concentrations above the maximum acceptable objective.

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Section: Hours and Days Exceeding The Maximum Acceptable Ozone Objective Of 82 Ppbmentioning

confidence: 99%

Ground-Level Ozone in Eastern Canada: Seasonal Variations, Trends, and Occurrences of High Concentrations

Fuentes

Dann²

1994

Air & Waste

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“…Some of this early work (e.g., Yap et al, 1988) suggested that local impacts on ozone levels were generally small, while some noted a more significant impact (Mukammal et al, 1982(Mukammal et al, , 1985. Ozone concentration increases of 30 ppbv over the course of a few minutes were linked through surface station and satellite observations to the passage of a lake-breeze front in a later, more detailed analysis (Hastie et al, 1999).…”

Section: Introductionmentioning

confidence: 99%

Mass tracking for chemical analysis: the causes of ozone formation in southern Ontario during BAQS-Met 2007

et al. 2010

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Abstract.A three-level nested regional air pollution model has been used to study the processes leading to high ozone concentrations in the southern Great Lakes region of North America. The highest resolution simulations show that complex interactions between the lake-breeze circulation and the synoptic flow lead to significant enhancements in the photochemical production and transport of ozone at the local scale. Mass tracking of individual model processes show that Lakes Erie and St. Clair frequently act as photochemical ozone production regions, with average mid-day production rates of up to 3 ppbv per hour. Enhanced ozone levels are evident over these two lakes in 23-day-average surface ozone fields. Analysis of other model fields and aircraft measurements suggests that vertical circulation enhances ozone levels at altitudes up to 1500 m over Lake St. Clair, whereas subsidence enhances ozone over Lake Erie in a shallow layer only 250 m deep. Mass tracking of model transport shows that lake-breeze surface convergence zones combined with the synoptic flow can then carry ozone and its precursors hundreds of kilometers from these source areas, in narrow, elongated features. Comparison with surface mesonet ozone observations confirm the presence, magnitude, and timing of these features, which can create local ozone enhancements on the order of 30 ppbv above the regional ozone levels. Sensitivity analyses of model-predicted ozone and HO x concentrations show that most of the region is VOC-limited, and that the secondary oxidation pathways of aromatic hydrocarbons have a key role in setting the region's ozone and HO x levels.

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“…Stratospheric intrusions have long been linked to short‐lived increases in surface O 3 [ Chung and Dann , 1985; Haagenson et al , 1981; Mukammal et al , 1985; Viezee et al , 1983], particularly at higher elevations [ Ambrose et al , 2011; Davies and Schuepbach , 1994; Langford et al , 2009a; Stohl et al , 2000]. The importance of STT as a source for surface O 3 remains highly uncertain, however.…”

Section: Introductionmentioning

confidence: 99%

Stratospheric influence on surface ozone in the Los Angeles area during late spring and early summer of 2010

et al. 2012

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The influence of stratosphere‐to‐troposphere transport (STT) on surface ozone (O3) concentrations in the greater Los Angeles area during the CalNex and IONS‐2010 measurement campaigns has been investigated. Principal component analysis (PCA) of surface O3measurements from 41 sampling stations indicates that ∼13% of the variance in the maximum daily 8‐h average (MDA8) O3between May 10 and June 19, 2010 was associated with changes of 2–3 day duration linked to the passage of upper‐level troughs. Ozonesondes launched from Joshua Tree National Park and airborne lidar measurements show that these changes coincided with the appearance of stratospheric intrusions in the lower troposphere above southern California. The Lagrangian particle dispersion model FLEXPART reproduces most of these intrusions, and supports the conclusion from the PCA that significant transport of stratospheric air to the surface occurred on May 28–30. This intrusion led to a peak 1‐h O3 concentration of 88 ppbv at Joshua Tree National Monument near the ozonesonde launch site on May 28, and widespread entrainment of stratospheric air into the boundary layer increased the local background O3 over the entire area to ∼55 ppbv on May 29–30. This background was 10–15 ppbv higher than the baseline O3 in air transported ashore from the Pacific Ocean, and when combined with locally produced O3 led to several exceedances of the current National Ambient Air Quality Standard (NAAQS) on the following day.

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Some features of the ozone climatology of Ontario, Canada and possible contributions of stratospheric ozone to surface concentrations

Cited by 15 publications

References 18 publications

Ground-Level Ozone in Eastern Canada: Seasonal Variations, Trends, and Occurrences of High Concentrations

Ground-Level Ozone in Eastern Canada: Seasonal Variations, Trends, and Occurrences of High Concentrations

Mass tracking for chemical analysis: the causes of ozone formation in southern Ontario during BAQS-Met 2007

Stratospheric influence on surface ozone in the Los Angeles area during late spring and early summer of 2010

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