Observations of Transport Processes for Ozone and Ozone Precursors during the 1991 Lake Michigan Ozone Study

Dye, Timothy S.; Roberts, Paul T.; Korc, Marcelo

doi:10.1175/1520-0450(1995)034<1877:ootpfo>2.0.co;2

Cited by 69 publications

(97 citation statements)

References 5 publications

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“…greater Chicago), and Southeastern Wisconsin (i.e. greater Milwaukee) (Dye et al 1995). On the synoptic (or regional) scale, it has been known for over 20 yr that very large (2000 km diameter) volumes of air in the Eastern US can become universally polluted with ozone (henceforth referred to as 'air-mass' ozone).…”

Section: Ozone Source Areas and Transportmentioning

confidence: 99%

“…From similarities between 2 case studies of ozone exceedances in the LMAQR, Dye et al (1995) developed a generalized conceptual model of ozone formation and transport. An integral aspect of their conceptual model -consistent with the ideas of Hanna & Chang (1995) and OTAG (Guinnup & Collum 1997a) -regards the link between ozone episodes in EWI and large ozone-rich high pressure systems to the east of the LMAQR.…”

Section: Ozone Source Areas and Transportmentioning

confidence: 99%

“…An integral aspect of their conceptual model -consistent with the ideas of Hanna & Chang (1995) and OTAG (Guinnup & Collum 1997a) -regards the link between ozone episodes in EWI and large ozone-rich high pressure systems to the east of the LMAQR. Dye et al (1995) concluded that such systems transport in high concentrations of ozone and precursors from outside the LMAQR, thereby raising ozone concentrations within the LMAQR, and increasing the likelihood of exceedances in EWI. It is important to emphasize, however, that like Hanna & Chang's (1995) study, Dye et al's (1995) conclusions are based on a small number of cases.…”

Section: Ozone Source Areas and Transportmentioning

confidence: 99%

“…While 'case study' examinations like Hanna & Chang (1995) and Dye et al (1995) have significantly added to our understanding of EWI's ozone problem, there is a limiting factor inherent to this approach: only a small number of events can be analyzed. This is a crucial weakness, since designing an emission control strategy that will significantly lower ozone levels in EWI requires the identification of modes of atmospheric circulation most closely connected with high levels of ozone in EW.…”

Section: Investigative Approach -Objectivesmentioning

confidence: 99%

“…Map Pattern 1 (MP1) is the most frequently occurring pattern, with a frequency of 13.5% (Table 1) Hanna & Chang (1995), and Dye et al (1995) to have an association with elevated ozone across a large segment of the Eastern US, as well as the LMAQR.…”

Section: Map Patternmentioning

confidence: 99%

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A synoptic climatology of surface-level ozone in Eastern Wisconsin, USA

Lennartson¹,

Schwartz²

1999

Clim. Res.

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Areas in Eastern Wisconsin (EWI), USA, experience exceedances of the federal health standard for ozone each summer. Recent work from the Ozone Transport Assessment Group has provided support for the association between slowly migrating anticyclones over the Eastern United States and widespread amounts of high ozone throughout much of the region. Case studies have yielded additional evidence of this connection, and, further, have shown that synoptic-scale transport in association with this anticyclone can be an important factor in elevating ozone levels in EWI. A case study approach however is limited since only a small number of events can be analyzed. To address this deficiency, our investigation employed a synoptic climatology, which is capable of linking patterns of atmospheric circulation with patterns of tropospheric ozone over an extended period of time. To classify the atmospheric circulation a correlation-based scheme was applied to 30 yr of gridded sea-levelpressure data. Our synoptic climatology showed that the highest ozone levels occurred when an anticyclone was present to the east of the Lake Michigan Air Quality Region (LMAQR); the same type of anticyclone identified by others as being responsible for the transport of regional-scale ozone and precursors to the LMAQR. Our synoptic climatology, therefore, supports the contention that the synopticscale transport of ozone from the Southern and Eastern US plays an important role in episodes of elevated ozone in EWI. Moreover, our results suggest that synoptic-scale systems (i.e. anticyclones situated over the Eastern US), which operate at much greater space and time scales than sub-regional scale circulations, are likely to transport sufficient ozone into Eastern WI to often exceed the new 8 h, 80 ppb health standard -unless steps are taken to reduce regional-scale emissions.

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Section: Ozone Source Areas and Transportmentioning

confidence: 99%

Section: Ozone Source Areas and Transportmentioning

confidence: 99%

Section: Ozone Source Areas and Transportmentioning

confidence: 99%

Section: Investigative Approach -Objectivesmentioning

confidence: 99%

Section: Map Patternmentioning

confidence: 99%

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A synoptic climatology of surface-level ozone in Eastern Wisconsin, USA

Lennartson¹,

Schwartz²

1999

Clim. Res.

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Simulation of Neighborhood-Scale Air Quality with two-way coupled WRF-CMAQ over Southern Lake Michigan-Chicago Region

Montgomery¹,

Schnell

Adelman

et al. 2022

Preprint

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The southern Lake Michigan region of the United States, home to Chicago, Milwaukee, and other densely populated Midwestern cities, frequently experiences high pollutant episodes with unevenly distributed exposure and health burdens. Using the twoway coupled Weather Research Forecast and Community Multiscale Air Quality Model (WRF-CMAQ), we investigate criteria pollutants over a southern Lake Michigan domain using 1.3 and 4 km resolution hindcast simulations. We assess WRF-CMAQ's performance using data from the National Climate Data Center and EPA Air Quality System. Our 1.3 km simulation slightly improves on the 4 km simulation's meteorological and chemical performance while also resolving key details in areas of high exposure and impact, i.e., urban environments. At 1.3 km, we find that most air quality-relevant meteorological components of WRF-CMAQ perform at or above community benchmarks. WRF-CMAQ's chemical performance also largely meets community standards, with substantial nuance depending on the performance metric and component assessed. For example, hourly simulated NO2 and O3 are highly correlated with observations (r > 0.6) while PM2.5 is less so (r = 0.4).Similarly, hourly simulated NO2 and PM2.5 have low biases (<10%), whereas O3 biases are larger (<30%). Simulated spatial pollutant patterns show distinct urban-rural footprints, with urban NO2 and PM2.5 20-60% higher than rural, and urban O3 6% lower. We use our 1.3 km simulations to resolve high-pollution areas within individual urban neighborhoods and characterize changes in O3 regimes across tight spatial gradients. Our findings demonstrate both the benefits and limitations of high-resolution simulations, particularly over urban settings.

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The lake breeze–ground‐level ozone connection in eastern Wisconsin: a climatological perspective

Lennartson

Schwartz

2002

Intl Journal of Climatology

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The Lake Michigan Air Quality Region (LMAQR) experiences exceedances of the 1 h health standard for ozone numerous times each summer. Previous short-term investigations have revealed that the lake breeze circulation is connected with very high levels of ozone in eastern Wisconsin (EWI). Findings from one of the more recent short-term research efforts have led to the development of a generalized conceptual model that details the role that the lake breeze circulation plays in transporting ozone-rich air of the Lake Michigan conduction layer onshore to EWI. Short-term studies, however, are limited by the small number of cases examined. To understand the ozone-lake breeze relationship from a climatological perspective, we analysed the spatial and temporal pattern of 1 h ozone exceedances in EWI during the months of May through to September, over the period 1985-99. Further, we used Laird et al.'s recently developed technique for discriminating lake breeze days to determine which exceedance-days over the period of our climatology occurred in association with lake breezes.Our results show: (1) a decrease in both magnitude and frequency of exceedances of the 1 h ozone standard in EWI with increasing distance from the lakeshore; (2) a positive correlation between average onset time of the initial exceedance-hour and a site's distance from Lake Michigan; (3) a very high percentage of initial exceedance-hours occurring in association with southeasterly surface air flow; and (4) exceedances occurring in association with lake breezes 82.1% of the time at near-shore sites.Collectively, our findings provide strong evidence that the lake breeze circulation is closely associated with the distribution of ozone in EWI in both space and time. Moreover, our results show that the lake breeze circulation is directly associated with a significant proportion of the exceedances of the 1 h ozone standard in EWI-particularly at near-shore sites. Thus, mandated reductions in regional-scale NO x may be sufficient to allow 'inland' locations in EWI to meet the new 8 h, 80 ppb Environmental Protection Agency health standard. However, further reductions in volatile organic compounds and NO x within the major metropolitan centres of the LMAQR will likely be necessary if 'shoreline' locations in EWI are to meet the 1 h standard, and the stricter 8 h standard in the future.

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Observations of Transport Processes for Ozone and Ozone Precursors during the 1991 Lake Michigan Ozone Study

Cited by 69 publications

References 5 publications

A synoptic climatology of surface-level ozone in Eastern Wisconsin, USA

A synoptic climatology of surface-level ozone in Eastern Wisconsin, USA

Simulation of Neighborhood-Scale Air Quality with two-way coupled WRF-CMAQ over Southern Lake Michigan-Chicago Region

The lake breeze–ground‐level ozone connection in eastern Wisconsin: a climatological perspective

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