Quantifying the contribution of thermally driven recirculation to a high-ozone event along the Colorado Front Range using lidar

John T. Sullivan, Thomas J. McGee, Andrew O. Langford, Raul J. Alvarez, Christoph J. Senff, Patrick J. Reddy, Anne M. Thompson, Laurence W. Twigg, Grant K. Sumnicht, Pius Lee, Andrew Weinheimer, Christoph Knote, Russell W. Long, Raymond M. Hoff

Research output: Contribution to journalArticlepeer-review

33 Scopus citations


A high-ozone (O3) pollution episode was observed on 22 July 2014 during the concurrent “Deriving Information on Surface Conditions from Column and Vertically Resolved Observations Relevant to Air Quality” (DISCOVER-AQ) and “Front Range Air Pollution and Photochemistry Experiment” (FRAPPE) campaigns in northern Colorado. Surface O3 monitors at three regulatory sites exceeded the Environmental Protection Agency (EPA) 2008 National Ambient Air Quality Standard (NAAQS) daily maximum 8 h average (MDA8) of 75 ppbv. To further characterize the polluted air mass and assess transport throughout the event, measurements are presented from O3 and wind profilers, O3-sondes, aircraft, and surface-monitoring sites. Observations indicate that thermally driven upslope flow was established throughout the Colorado Front Range during the pollution episode. As the thermally driven flow persisted throughout the day, O3 concentrations increased and affected high-elevation Rocky Mountain sites. These observations, coupled with modeling analyses, demonstrate a westerly return flow of polluted air aloft, indicating that the mountain-plains solenoid circulation was established and impacted surface conditions within the Front Range.

Original languageEnglish (US)
Pages (from-to)10377-10390
Number of pages14
JournalJournal of Geophysical Research
Issue number17
StatePublished - Jan 1 2016

All Science Journal Classification (ASJC) codes

  • Geophysics
  • Forestry
  • Oceanography
  • Aquatic Science
  • Ecology
  • Water Science and Technology
  • Soil Science
  • Geochemistry and Petrology
  • Earth-Surface Processes
  • Atmospheric Science
  • Earth and Planetary Sciences (miscellaneous)
  • Space and Planetary Science
  • Palaeontology


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