Feb 27, 2017

Co-occurrence of extremes in surface ozone, particulate matter, and temperature over eastern North America

Jordan L. Schnell, Michael J. Prather
Proceedings of the National Academy of Sciences
  • Examines 15 years (1999–2013) of surface observations of "extended summer" (April through September) surface ozone (O3), fine particulate matter (PM2.5), and maximum temperature (TX) over the eastern United States and Canada
  • Constructs a climatology of the coincidence, overlap, and lag in space and time of each quantity's extremes
  • Defines extremes as the 50 days with the highest values in three 5-year windows (at the 95th percentile)
  • Finds that all three extremes occur primarily in large-scale, multiday, spatially connected episodes and coincide with large-scale meteorological features
  • Results show that the largest, longest-lived episodes have the highest incidence of co-occurrence
  • Results demonstrate the need to evaluate these extremes as synergistic costressors to accurately quantify their impacts on human health, as heat waves and air pollution episodes may worsen under future climate change