Assessing Temporal and Spatial Patterns of Observed and Predicted Ozone in Multiple Urban Areas

Simon, Heather; Wells, Benjamin B.; Baker, Kirk R.; Hubbell, Bryan

doi:10.1289/ehp190

Cited by 15 publications

(17 citation statements)

References 27 publications

(33 reference statements)

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“…With our sensitivity simulations, we interpret this lack of an overall trend as a balance between rising US background O 3 (by 2 ppb for O 3 _USB from 2004-2006 to 2010-2012 averaged over all regions) and declining US anthropogenic emissions (by 6 ppb for O 3 _USA from 2004-2006 to 2010-2012 averaged over all regions). The declining influence of US anthropogenic emissions on O 3 _top10obs_JJA days is consistent with earlier work showing high-O 3 concentrations decreasing in response to regional precursor emissions controls since the late 1990s (e.g., Cooper et al, 2012Cooper et al, , 2014Frost et al, 2006;Simon et al, 2016).…”

Section: Discussionsupporting

confidence: 89%

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Average versus high surface ozone levels over the continental USA: model bias, background influences, and interannual variability

et al. 2018

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Abstract. US background ozone (O3) includes O3 produced from anthropogenic O3 precursors emitted outside of the USA, from global methane, and from any natural sources. Using a suite of sensitivity simulations in the GEOS-Chem global chemistry transport model, we estimate the influence from individual background sources versus US anthropogenic sources on total surface O3 over 10 continental US regions from 2004 to 2012. Evaluation with observations reveals model biases of +0–19 ppb in seasonal mean maximum daily 8 h average (MDA8) O3, highest in summer over the eastern USA. Simulated high-O3 events cluster too late in the season. We link these model biases to excessive regional O3 production (e.g., US anthropogenic, biogenic volatile organic compounds (BVOCs), and soil NOx, emissions), or coincident missing sinks. On the 10 highest observed O3 days during summer (O3_top10obs_JJA), US anthropogenic emissions enhance O3 by 5–11 ppb and by less than 2 ppb in the eastern versus western USA. The O3 enhancement from BVOC emissions during summer is 1–7 ppb higher on O3_top10obs_JJA days than on average days, while intercontinental pollution is up to 2 ppb higher on average versus on O3_top10obs_JJA days. During the summers of 2004–2012, monthly regional mean US background O3 MDA8 levels vary by up to 15 ppb from year to year. Observed and simulated summertime total surface O3 levels on O3_top10obs_JJA days decline by 3 ppb (averaged over all regions) from 2004–2006 to 2010–2012, reflecting rising US background (+2 ppb) and declining US anthropogenic O3 emissions (−6 ppb) in the model. The model attributes interannual variability in US background O3 on O3_top10obs days to natural sources, not international pollution transport. We find that a 3-year averaging period is not long enough to eliminate interannual variability in background O3 on the highest observed O3 days.

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Section: Discussionsupporting

confidence: 89%

“…This station is analyzed as a standalone site in Sect. 3.2, given the relevance of high-altitude measurements for downwind surface O 3 (Stauffer et al, 2017). We take all hourly O 3 concentrations from Mount Bachelor and calculate the MDA8 O 3 concentrations for 2004-2012.…”

Section: Observationsmentioning

confidence: 99%

Average versus high surface ozone levels over the continental USA: model bias, background influences, and interannual variability

et al. 2018

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“…are consistent with what would be expected from substantial regional NOx reductions as has been documented previously. Specifically, modeling studies have linked decreases in regional emissions to decreases in high O 3 episodes in the US (Tagaris et al, 2007;Gilliland et al, 2008;Fiore, 2009;Xing et al, 2015) and EU (Jonson et al, 2006;Vautard et al, 2006), as well as increases in low O 3 concentrations at the same locations where high concentrations decrease (Jonson et al, 2006;Hogrefe et al, 2011;Simon et al, 2013;Downy et al, 2015;Simon et al, 2016). Additional evidence that regional emissions reductions can increase low O 3 concentrations comes from studies of measured concentrations.…”

Section: 1mentioning

confidence: 99%

Responses of human health and vegetation exposure metrics to changes in ozone concentration distributions in the European Union, United States, and China

Lefohn¹,

Malley

Simon

et al. 2017

Atmospheric Environment

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The impacts of surface ozone (O 3) on human health and vegetation have prompted O 3 precursor emission reductions in the European Union (EU) and United States (US). In contrast, until recently, emissions have increased in East Asia and most strongly in China. As emissions change, the distribution of hourly O 3 concentrations also changes, as do the values of exposure metrics. The distribution changes can result in the exposure metric trend patterns changing in a similar direction as trends in emissions (e.g., metrics increase as emissions increase) or, in some cases, in opposite directions. This study, using data from 481 sites (276 in the EU, 196 in the US, and 9 in China), investigates the response of 14 human health and vegetation O 3 exposure metrics to changes in hourly O 3 concentration distributions over time. At a majority of EU and US sites, there was a reduction in the frequency of both relatively high and low hourly average O 3 concentrations. In contrast, for some sites in mainland China and Hong Kong, the middle of the distribution shifted upwards but the low end did not change and for other sites, the entire distribution shifted upwards. The responses of the 14 metrics to these changes at the EU, US, and Chinese sites were varied, and dependent on (1) the extent to which the metric was determined by relatively high, moderate, and low concentrations and (2) the relative magnitude of the shifts occurring within the O 3 concentration distribution. For example, the majority of the EU and US sites experienced decreasing trends in the magnitude of those metrics associated with higher concentrations. For the sites in China, all of the metrics either increased or had no trends. In contrast, there were a greater number of sites that had no trend for those metrics determined by a combination of moderate and high O 3 concentrations. A result of our analyses is that trends in mean or median concentrations did not appear to be well associated with some exposure metrics applicable for assessing human health or vegetation effects. The identification of shifting

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“…The current spacing is not sufficient to capture high spatial resolution concentrations (Bart et al, 2014;Moltchanov et al, 2015). Additionally, this variability could potentially be used to inform exposure assessment for health studies as well as improve our understanding of pollutant sources and fate (Simon et al, 2016;Lin et al, 2015;Blanchard et 10 al., 2014).…”

mentioning

confidence: 99%

Intra-urban spatial variability of surface ozone and carbon dioxide in Riverside, CA: viability and validation of low-cost sensors

Sadighi

Coffey

Polidori

et al. 2017

Preprint

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Abstract. Sensor networks are being more widely used to characterize and understand compounds in the atmosphere such as ozone and carbon dioxide. This study employs a measurement tool, called the U-Pod, constructed at the University of Colorado Boulder, to investigate spatial and temporal variability of O3 and CO2 in a 314 km 2 area of Riverside County near Los Angeles, 10California. This tool provides low-cost sensors to collect ambient data at non-permanent locations. The U-Pods were calibrated using a pre-deployment field calibration technique; all the U-Pods were collocated with regulatory monitors. After collocation, the U-Pods were deployed in the area mentioned. A subset of pods was deployed at two local regulatory air quality monitoring stations providing validation for the collocation calibration method. Field validation of sensor O3 and CO2 measurements to minute resolution reference observations resulted in R-squared and root mean squared errors (RMSE) of 0.95 -0.97 and 4.4 -15 7.2 ppbv for O3 and 0.79 and 15 ppmv CO2, respectively. Using the deployment data, ozone and carbon dioxide concentrations were observed to vary on this small spatial scale. In the analysis based on hourly binned data, the median R-squared values between all possible U-Pod pairs varied from 0.52 to 0.86 for ozone during the deployment. The medians of absolute differences were calculated between all possible pod pairs, 21 pairs total. The median values of those median absolute differences for each hour of the day varied between 2.2 and 9.3 ppb for the ozone deployment. For carbon dioxide, distributions 20 of all measurements vary from 413 -425 ppm during the calibration (collocation) and 406 -472 during the deployment. Since median differences between U-Pod concentrations during deployment are larger than the respective root mean square error values for ozone and carbon dioxide, we can conclude that there is spatial variability in these pollutants across the study area. This is important because it means that citizens may be exposed to more ozone than they would assume based on current regulatory monitoring. 25Atmos. Meas. Tech. Discuss., https://doi

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Assessing Temporal and Spatial Patterns of Observed and Predicted Ozone in Multiple Urban Areas

Cited by 15 publications

References 27 publications

Average versus high surface ozone levels over the continental USA: model bias, background influences, and interannual variability

Average versus high surface ozone levels over the continental USA: model bias, background influences, and interannual variability

Responses of human health and vegetation exposure metrics to changes in ozone concentration distributions in the European Union, United States, and China

Intra-urban spatial variability of surface ozone and carbon dioxide in Riverside, CA: viability and validation of low-cost sensors

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