Chapter 71
Linking North American Summer Ozone
Pollution Episodes to Subseasonal
Atmospheric Variability
E. Charles White, Dylan Jones and Paul Kushner
Abstract Extreme ozone pollution episodes can cause acute stress on the human
respiratory system and damage vegetation. This study leverages long-term ozone
measurement records from the United States Environmental Protection Agency Air
Quality System (AQS) and the Environment and Climate Change Canada National
Air Pollution Surveillance Program (NAPS) to identify ozone pollution episodes
in summertime North America and assess meteorological patterns typical for those
events. For this purpose, methods are adapted from studies of heat waves that similarly rely on station-based measurement records. Clustering methods are used to
group ozone monitoring stations into large regions according to their likelihood
of recording simultaneous ozone extremes. Multiday periods with abnormally high
cluster-wide ozone concentrations are then identified as ozone episodes. Composite
meteorological patterns associated with the ozone enhancement episodes are separately derived for each region. The composite patterns exhibit features commonly
associated with elevated ozone, such as high temperatures and reduced cloud cover.
In most regions, these features appear alongside anomalous synoptic-scale anticyclonic circulation in the mid-troposphere. These systems are themselves embedded
in large-scale wave trains extending from the Pacific. The wave trains develop more
than a week in advance of ozone episode onset and are plausibly related to sea
surface temperature patterns with subseasonal persistence that also emerge in the
composite meteorology. The persistence of these ozone episode circulation patterns
could potentially be leveraged to improve forecasting and long-term projections of
air quality.
71.1 Introduction
Ozone is an airborne pollutant that causes oxidative stress to the human respiratory
system [10] and damages vegetation [5]. Short-term acute ozone exposure has been
E. C. White (B) · D. Jones · P. Kushner
Department of Physics, University of Toronto, Toronto, ON M5S 1A7, Canada
e-mail: cwhite@physics.utoronto.ca
© Springer Nature Switzerland AG 2020
C. Mensink et al. (eds.), Air Pollution Modeling and its Application XXVI,
Springer Proceedings in Complexity,
https://doi.org/10.1007/978-3-030-22055-6_71
445
Linking North American Summer Ozone
Pollution Episodes to Subseasonal
Atmospheric Variability
E. Charles White, Dylan Jones and Paul Kushner
Abstract Extreme ozone pollution episodes can cause acute stress on the human
respiratory system and damage vegetation. This study leverages long-term ozone
measurement records from the United States Environmental Protection Agency Air
Quality System (AQS) and the Environment and Climate Change Canada National
Air Pollution Surveillance Program (NAPS) to identify ozone pollution episodes
in summertime North America and assess meteorological patterns typical for those
events. For this purpose, methods are adapted from studies of heat waves that similarly rely on station-based measurement records. Clustering methods are used to
group ozone monitoring stations into large regions according to their likelihood
of recording simultaneous ozone extremes. Multiday periods with abnormally high
cluster-wide ozone concentrations are then identified as ozone episodes. Composite
meteorological patterns associated with the ozone enhancement episodes are separately derived for each region. The composite patterns exhibit features commonly
associated with elevated ozone, such as high temperatures and reduced cloud cover.
In most regions, these features appear alongside anomalous synoptic-scale anticyclonic circulation in the mid-troposphere. These systems are themselves embedded
in large-scale wave trains extending from the Pacific. The wave trains develop more
than a week in advance of ozone episode onset and are plausibly related to sea
surface temperature patterns with subseasonal persistence that also emerge in the
composite meteorology. The persistence of these ozone episode circulation patterns
could potentially be leveraged to improve forecasting and long-term projections of
air quality.
71.1 Introduction
Ozone is an airborne pollutant that causes oxidative stress to the human respiratory
system [10] and damages vegetation [5]. Short-term acute ozone exposure has been
E. C. White (B) · D. Jones · P. Kushner
Department of Physics, University of Toronto, Toronto, ON M5S 1A7, Canada
e-mail: cwhite@physics.utoronto.ca
© Springer Nature Switzerland AG 2020
C. Mensink et al. (eds.), Air Pollution Modeling and its Application XXVI,
Springer Proceedings in Complexity,
https://doi.org/10.1007/978-3-030-22055-6_71
445