Meteorological conditions associated with ozone in southwestern Ontario, Canada

Mukammal, E. I.; Neumann, H. H.; Gillespie, T. J.

doi:10.1016/0004-6981(82)90281-5

Cited by 20 publications

(9 citation statements)

References 13 publications

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“…On one day only in each of the two intermediate speed ranges were ozone concentrations above 120 ppb and 153 ppb observed on a day with southerly wind components in the spring. The above results verify the finding of Mukammal [ 13 ] that the most frequent and highest ozone concentrations did not seem to occur with either very light or strong surface winds, but were usually associated with a relatively light to moderate flow. The resultant air trajectory for the 24-48 hours (hereafter designated 2nd day trajectory) proceding the resultant 1st day (0 24 hours) trajectory was derived by subtracting the resultant 1st day air trajectory from that for the 0-48 hours period.…”

Section: Favourable Meteorological Conditionssupporting

confidence: 91%

“…During 1978 there were 70 potential days of elevated ozone in contrast to 39 days in 1980. July had the maximum monthly average number of potential days [13], followed by June, May, August, September, March and April (11.0, 9.75, 9.25, 5.25, 3.5 and 3.0 days respectively), with an annual average of 55 days. May had the highest average number of potential days (2) for the entrainment of stratospheric ozone into the troposphere followed by April (1 day), June (1/2), August (1/2) and July (a/4 day).…”

Section: Favourable Meteorological Conditionsmentioning

confidence: 99%

“…Meteorological conditions as a function of air masses prevailing during abnormally high photochemically-generated ozone from anthropogenic precursors over southwestern Ontario in July and August 1978 are discussed by Mukammal [ 13 ]. They are mainly associated with large-scale motion systems, which can advect ozone and its precursors over distances of several hundred kilometers, together with regional and local-scale motions, such as the onset of lake breeze, causing fumigation as a result of quasi-stationary high pressure systems crossing the eastern United States.…”

Section: Favourable Meteorological Conditionsmentioning

confidence: 99%

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

Mukammal

Neuman

Nichols

1985

Arch. Met. Geoph. Biocl. A.

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SummaryBackground ozone concentration displayed distinct seasonal variations at all stations, with a maximum of about 40 ppb in spring and a minimum of about 23 ppb in autumn. The monthly and yearly mean diurnal variations of ozone at urban stations exhibited bi-modal characteristics not evident at rural sites. Two daily maxima and minima were recorded at urban stations, but only one maximum and one minimum at rural sites. The second minimum in the evening at urban stations was shown to be related to high levels of nitric oxide, while nighttime heat island was considered the main cause of the second maximum. One-day resultant trajectories show that the most frequent and highest ozone concentrations were associated with a relatively light to moderate south to southwesterly flow but not with light or with strong winds. Although there were several recognizable meteorological regimes associated with elevated ozone concentrations over Ontario, those with weak pressure gradients favourable for the onset of lake breeze or with southwesterly flows on the west side of slow-moving high pressure centres crossing the eastern United States were the most frequent and resulted in the highest ozone concentrations. Ozone maxima over Ontario may mostly be attributed to long distance transport of emissions from major industrial areas south of the border. However, tropospheric and stratospheric contributions cannot be ruled out and may even be a major source at times. A case study of possible stratospheric ozone influx into the troposphere is presented. Zusammenfassung Grundlagen der Ozonklimatologie der

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Section: Favourable Meteorological Conditionssupporting

confidence: 91%

Section: Favourable Meteorological Conditionsmentioning

confidence: 99%

Section: Favourable Meteorological Conditionsmentioning

confidence: 99%

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

Mukammal

Neuman

Nichols

1985

Arch. Met. Geoph. Biocl. A.

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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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“…For example, some of the earliest studies (Shenfeld, Yap, & Kurtz, 1978;Yap & Chung, 1977) showed that high and low O 3 concentrations in southern Ontario occurred when an anticyclone was located to the east and west of the province, respectively. Using data for July andAugust 1978, Mukammal, Neumann, andGillespie (1982) discovered a strong curvilinear relationship between daily average O 3 concentrations in southwestern Ontario and the wet bulb potential temperature for the surface mixed layer derived from upstream radiosonde ascents. Heidorn and Yap (1986) manually classified six weather types using daily surface weather maps for the period 1976-1981 and analyzed their relationships with O 3 concentrations.…”

mentioning

confidence: 97%

A Synoptic Climatological Approach to Assess Climatic Impact on Air Quality in South-central Canada. Part I: Historical Analysis

Cheng

Campbell

et al. 2007

Water Air Soil Pollut

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Automated synoptic weather typing and robust orthogonal stepwise regression analysis (via principal components analysis) were applied together to develop within-weather-type air pollution prediction models for a variety of pollutants (specifically, carbon monoxide -CO, nitrogen dioxide -NO 2 , ozone -O 3 , sulphur dioxide -SO 2 , and suspended particles -SP) for the period 1974-2000 in south-central Canada. The SAS robust regression procedure was used to limit the influence of outliers on air pollution prediction algorithms. Six-hourly Environment Canada surface observed meteorological data and 6-hourly US National Centers for Environmental Prediction (NCEP) reanalysis data of various weather elements were used in the analysis. The models were developed using twothirds of the total years for meteorological and air pollution data; the remaining one-third (randomly selected) was used for model validation. Robust stepwise regression analysis was performed to analytically determine the meteorological variables that might be used to predict air pollution concentrations. There was a significant correlation between observed daily mean air pollution concentrations and model predictions. About 20, 50, and 80% of the 80 prediction models across the study area possessed R 2 values ≥ 0.7, 0.6, and 0.5, respectively. The results of model validation were similar to those of model development, with slightly smaller model R 2 values.

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Meteorological conditions associated with ozone in southwestern Ontario, Canada

Cited by 20 publications

References 13 publications

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

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

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

A Synoptic Climatological Approach to Assess Climatic Impact on Air Quality in South-central Canada. Part I: Historical Analysis

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