title: Variability and sources of surface ozone at rural sites in Nevada, USA: Results from two years of the Nevada Rural Ozone Initiative.
abstract: Ozone (O3) has been measured at Great Basin National Park (GBNP) since September 1993. GBNP is located in a remote, rural area of eastern Nevada. Data indicate that GBNP will not comply with a more stringent National Ambient Air Quality Standard (NAAQS) for O3, which is based upon the 3-year average of the annual 4th highest Maximum Daily 8-h Average (MDA8) concentration. Trend analyses for GBNP data collected from 1993 to 2013 indicate that MDA8 O3 increased significantly for November to February, and May. The greatest increase was for May at 0.38, 0.35, and 0.46 ppb yr(-1) for the 95th, 50th, and 5th percentiles of MDA8 O3 values, respectively. With the exception of GBNP, continuous O3 monitoring in Nevada has been limited to the greater metropolitan areas. Due to the limited spatial detail of O3 measurements in rural Nevada, a network of rural monitoring sites was established beginning in July 2011. For a period ranging from July 2011 to June 2013, maximum MDA8 O3 at 6 sites occurred in the spring and summer, and ranged from 68 to 80ppb. Our analyses indicate that GBNP, in particular, is ideally positioned to intercept air containing elevated O3 derived from regional and global sources. For the 2 year period considered here, MDA8 O3 at GBNP was an average of 3.1 to 12.6 ppb higher than at other rural Nevada sites. Measured MDA8 O3 at GBNP exceeded the current regulatory threshold of 75 ppb on 7 occasions. Analyses of synoptic conditions, model tracers, and air mass back-trajectories on these days indicate that stratospheric intrusions, interstate pollution transport, wildfires, and Asian pollution contributed to elevated O3 observed at GBNP. We suggest that regional and global sources of ozone may pose challenges to achieving a more stringent O3 NAAQS in rural Nevada.
authors.affiliation: Department of Natural Resources and Environmental Science, University of Nevada-Reno, Reno, NV, USA. Electronic address: rebekkafine@gmail.com.
authors.forename: Rebekka
authors.initials: R
authors.lastname: Fine
authors.affiliation: Department of Natural Resources and Environmental Science, University of Nevada-Reno, Reno, NV, USA.
authors.forename: Matthieu B
authors.initials: MB
authors.lastname: Miller
authors.affiliation: Department of Chemistry, St. Mary's College of California, Moraga, CA, USA.
authors.forename: Joel
authors.initials: J
authors.lastname: Burley
authors.affiliation: Science and Technology Program, University of Washington-Bothell, Bothell, WA, USA; Department of Atmospheric Sciences, University of Washington-Seattle, Seattle, WA, USA.
authors.forename: Daniel A
authors.initials: DA
authors.lastname: Jaffe
authors.affiliation: NOAA/NESDIS Center for Satellite Application and Research, Madison, WI, USA.
authors.forename: R Bradley
authors.initials: RB
authors.lastname: Pierce
authors.affiliation: Atmospheric and Oceanic Sciences, Princeton University, Princeton, NJ, USA; Geophysical Fluid Dynamics Laboratory, NOAA, Princeton, NJ, USA.
authors.forename: Meiyun
authors.initials: M
authors.lastname: Lin
authors.affiliation: Department of Natural Resources and Environmental Science, University of Nevada-Reno, Reno, NV, USA. Electronic address: mgustin@cabnr.unr.edu.
authors.forename: Mae Sexauer
authors.initials: MS
authors.lastname: Gustin
mesh_terms: D000393:Air Pollutants / Q000032:analysis*; D000397:Air Pollution / Q000706:statistics & numerical data; D004784:Environmental Monitoring; D009505:Nevada; D010126:Ozone / Q000032:analysis*
chemical_list: D000393:Air Pollutants; D010126:Ozone
keywords: Interstate transport; Long-range transport; National Ambient Air Quality Standards; Ozone air quality; Stratospheric intrusions; Wildfires