Variability and sources of surface ozone at rural sites in Nevada, USA: Results from two years of the Nevada Rural Ozone Initiative

Fine, Rebekka; Miller, Matthieu B.; Burley, Joel D.; Jaffe, Daniel A.; Pierce, R. Bradley; Lin, Meiyun; Gustin, Mae Sexauer

doi:10.1016/j.scitotenv.2014.12.027

Cited by 27 publications

(35 citation statements)

References 29 publications

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“…JOT, one of the sites most influenced by urban emissions, showed distinctly different behaviors, with only 0.2 ppb increase in 2012. Previous observation‐based analyses have reported a springtime increase in MDA8 O 3 at U.S. surface sites in the Pacific northwest (Baylon et al, ; Fine et al, ) associated with an influx of O 3 from the UT/S (Baylon et al, ; Lin et al, ). The increases reported in this study fall inside the range of those reported by Baylon et al ().…”

Section: Resultssupporting

confidence: 73%

An Assessment of Ground Level and Free Tropospheric Ozone Over California and Nevada

et al. 2017

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Increasing free tropospheric ozone (O3), combined with the high elevation and often deep boundary layers at western U.S. surface stations, poses challenges in attaining the more stringent 70 ppb O3 National Ambient Air Quality Standard. As such, use of observational data to identify sources and mechanisms that contribute to surface O3 is increasingly important. This work analyzes surface and vertical O3 observations over California and Nevada from 1995 to 2015. Over this period, the number of high O3 events (95th percentile) at the U.S. Environmental Protection Agency Clean Air Status and Trends Network (CASTNET) sites has decreased during summer, as a result of decreasing U.S. emissions. In contrast, an increase in springtime 5th percentile O3 indicates a general increase of baseline O3. During 2012 there was a peak in exceedances and in the average spring‐summer O3 mixing ratios at CASTNET sites. Goddard Earth Observing System‐Chem results show that the surface O3 attributable to transport from the upper troposphere and stratosphere was increased in 2013 compared to 2012, highlighting the importance of measurements aloft. Vertical O3 measurements from aircraft, ozonesondes, and lidar show distinct seasonal trends, with a high percentage of elevated O3 laminae (O3 > 70 ppb, 3–8 km) during spring and summer. Analysis of the timing of high O3 surface events and correlation between surface and vertical O3 data is used to discuss varying sources of western U.S. surface O3.

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Section: Resultssupporting

confidence: 73%

An Assessment of Ground Level and Free Tropospheric Ozone Over California and Nevada

et al. 2017

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“…50 This is in-contrast to the other high elevation sites that remain exposed to the free troposphere at night. 51 However, at other high elevation sites, during the nighttime these locations would remain exposed to the free troposphere where recent work has shown high concentrations. 33,38,52 The precipitation amount at CCRS was 45 and 0 mm in July-Sep 2012 and 2013, respectively (Remote Automated Weather Station).…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Use of Passive Sampling Methods and Models to Understand Sources of Mercury Deposition to High Elevation Sites in the Western United States

Huang

Gustin

2014

Environ. Sci. Technol.

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To understand gaseous oxidized mercury (GOM) sources to the Western US, data were collected with passive samplers for ambient GOM concentrations and dry deposition at 10 sites from the coast of the Pacific Ocean to Great Basin National Park. Tests were done to better understand the samplers and the materials used. Measured dry deposition of GOM was significantly higher at sites >2000 m elevation relative to those below due to high GOM concentrations and atmospheric turbulence. At these high elevation sites, GOM dry deposition was higher in spring due to long-range transport from Asia (air parcels from the free troposphere) and some high GOM dry deposition events were related to regional emissions. Dry deposition of GOM at two sites was calculated using the passive sampler data and a multiple-resistance model. A previously developed relationship between the sampling rate of the passive sampler and GOM concentrations was used to estimate dry deposition and a scaling factor of 3 was used to adjust GOM concentrations, due to underestimation by KCl-coated denuder measurements. With the scaling factor of 3, modeled deposition was in the range of results estimated from two different models settings. However, dry deposition did not correlate consistently with either model. The disagreement could be due to uncertainties associated with measurements and/or modeling, or different GOM compounds existing in the atmosphere. If the atmospheric GOM compounds are known, dry deposition velocities could be estimated more accurately. Lastly, we investigated the potential for use of a new sampling material for GOM and checked the efficiency of the passive sampler.

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“…Individual NCOS events have long been associated with episodic increases in surface O 3 , and much of our knowledge about their impacts in the U.S. and Canada has been inferred from routine ground-based measurements coupled with meteorological analyses (Ambrose et al, 2011;Fine et al, 2015;Jaffe and Zhang, 2017;Lefohn et al, 2012;Stauffer et al, 2017;Teakles et al, 2017;Wigder et al, 2013a, b) or with models and satellite retrievals (He et al, 2011;Lin et al, 2012a, b). These studies have been hampered by the sparsity of surface O 3 monitors in the western states where the impacts tend to be greatest , and by limited free tropospheric measurements by aircraft (Yates et al, 2013), ozonesondes (He et al, 2011), or lidars (Kuang et al, 2012;Langford et al, 2018).…”

Section: Evidence For Ncos From Observations and Modelsmentioning

confidence: 99%

Scientific assessment of background ozone over the U.S.: Implications for air quality management

Jaffe

Cooper

Fiore

et al. 2018

Elementa: Science of the Anthropocene

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109

149

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Ozone (O3) is a key air pollutant that is produced from precursor emissions and has adverse impacts on human health and ecosystems. In the U.S., the Clean Air Act (CAA) regulates O3levels to protect public health and welfare, but unraveling the origins of surface O3is complicated by the presence of contributions from multiple sources including background sources like stratospheric transport, wildfires, biogenic precursors, and international anthropogenic pollution, in addition to U.S. anthropogenic sources. In this report, we consider more than 100 published studies and assess current knowledge on the spatial and temporal distribution, trends, and sources of background O3over the continental U.S., and evaluate how it influences attainment of the air quality standards. We conclude that spring and summer seasonal mean U.S. background O3(USB O3), or O3formed from natural sources plus anthropogenic sources in countries outside the U.S., is greatest at high elevation locations in the western U.S., with monthly mean maximum daily 8-hour average (MDA8) mole fractions approaching 50 parts per billion (ppb) and annual 4thhighest MDA8s exceeding 60 ppb, at some locations. At lower elevation sites, e.g., along the West and East Coasts, seasonal mean MDA8 USB O3is in the range of 20–40 ppb, with generally smaller contributions on the highest O3days. The uncertainty in U.S. background O3is around ±10 ppb for seasonal mean values and higher for individual days. Noncontrollable O3sources, such as stratospheric intrusions or precursors from wildfires, can make significant contributions to O3on some days, but it is challenging to quantify accurately these contributions. We recommend enhanced routine observations, focused field studies, process-oriented modeling studies, and greater emphasis on the complex photochemistry in smoke plumes as key steps to reduce the uncertainty associated with background O3in the U.S.

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Variability and sources of surface ozone at rural sites in Nevada, USA: Results from two years of the Nevada Rural Ozone Initiative

Cited by 27 publications

References 29 publications

An Assessment of Ground Level and Free Tropospheric Ozone Over California and Nevada

An Assessment of Ground Level and Free Tropospheric Ozone Over California and Nevada

Use of Passive Sampling Methods and Models to Understand Sources of Mercury Deposition to High Elevation Sites in the Western United States

Scientific assessment of background ozone over the U.S.: Implications for air quality management

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