1Laboratory for Climate and Ocean–Atmosphere Sciences, Department of
Atmospheric and Oceanic Sciences, School of Physics, Peking University,
Beijing 100871, China
2Climate Change Research Center, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China
3Department of Civil and Environmental Engineering, Viterbi School of
Engineering, University of Southern California, Los Angeles, CA 90089, USA
4School of Science, Technology, Engineering and Math, University of Washington Bothell, Bothell, WA 98011, USA
5Department of Atmospheric Sciences, University of Washington, Seattle, WA 98195, USA
6Norwegian Institute for Air Research, 2007 Kjeller, Norway
1Laboratory for Climate and Ocean–Atmosphere Sciences, Department of
Atmospheric and Oceanic Sciences, School of Physics, Peking University,
Beijing 100871, China
2Climate Change Research Center, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China
3Department of Civil and Environmental Engineering, Viterbi School of
Engineering, University of Southern California, Los Angeles, CA 90089, USA
4School of Science, Technology, Engineering and Math, University of Washington Bothell, Bothell, WA 98011, USA
5Department of Atmospheric Sciences, University of Washington, Seattle, WA 98195, USA
6Norwegian Institute for Air Research, 2007 Kjeller, Norway
Received: 19 Jul 2016 – Discussion started: 26 Jul 2016 – Revised: 06 Nov 2016 – Accepted: 09 Nov 2016 – Published: 24 Nov 2016
Abstract. Increasing wildfire activities in the mountainous western US may present a challenge for the region to attain a recently revised ozone air quality standard in summer. Using current Eulerian chemical transport models to examine the wildfire ozone influences is difficult due to uncertainties in fire emissions, inadequate model chemistry, and resolution. Here we quantify the wildfire influence on the ozone variability, trends, and number of high MDA8 (daily maximum 8 h average) ozone days over this region in summers (June, July, and August) 1989–2010 using a new approach. We define a fire index using retroplumes (plumes of back-trajectory particles) computed by a Lagrangian dispersion model (FLEXPART) and develop statistical models based on the fire index and meteorological parameters to interpret MDA8 ozone concentrations measured at 13 Intermountain West surface sites. We show that the statistical models are able to capture the ozone enhancements by wildfires and give results with some features different from the GEOS-Chem Eulerian chemical transport model. Wildfires enhance the Intermountain West regional summer mean MDA8 ozone by 0.3–1.5 ppbv (daily episodic enhancements reach 10–20 ppbv at individual sites) with large interannual variability, which are strongly correlated with the total MDA8 ozone. We find large fire impacts on the number of exceedance days; for the 13 CASTNet sites, 31 % of the summer days with MDA8 ozone exceeding 70 ppbv would not occur in the absence of wildfires.
Increasing wildfire activities in the mountainous western US may present a challenge for the region to attain a recently revised ozone air quality standard in summer. We quantify the wildfire influence on the ozone variability, trends, and number of high ozone days over this region in summers 1989–2010 using a Lagrangian dispersion model and statistical regression models.
Increasing wildfire activities in the mountainous western US may present a challenge for the...
