Background ozone levels of air entering the west coast of the US and assessment of longer-term changes

Oltmans, S. J.; Lefohn, Allen S.; Harris, Joyce M.; Shadwick, Douglas S.

doi:10.1016/j.atmosenv.2008.03.034

Cited by 105 publications

(139 citation statements)

References 19 publications

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“…The amplitude of the annual signal (approximately 14 ppbv) is 5 ppbv less than that reported for Cheeka Peak or Trinidad Head (TDH), California (Oltmans et al, 2008) which are both lower-altitude marine boundary layer sites. The observed ozone cycle at Whistler differs from other high elevation sites in the western US such as Rocky Mountain and Lassen National Parks (Jaffe and Ray, 2007;Jaffe, 2011) or from ozonesondes flown at TDH .…”

Section: Ozonementioning

confidence: 86%

“…These sites have the spring ozone peak but also have a significant summer peak, sometimes exceeding the springtime maxima. The Whistler ozone data do not show this broad summer maximum and more closely resemble the annual ozone pattern from the coastal TDH site (Oltmans et al, 2008) although monthly median mixing ratios are 3-15 ppbv higher at Whistler (O 3 WHI = 0.7 (O 3 TDH) +19.8 ppbv; R 2 = 0.74, n = 56). The small secondary peak often observed in August at Whistler was not observed at TDH, and corresponded with increases in Whistler CO, possibly indicative of regional pollution or influences of biomass burning.…”

Section: Ozonementioning

confidence: 99%

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Interannual variability of ozone and carbon monoxide at the Whistler high elevation site: 2002–2006

et al. 2011

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Section: Ozonementioning

confidence: 86%

Section: Ozonementioning

confidence: 99%

Interannual variability of ozone and carbon monoxide at the Whistler high elevation site: 2002–2006

et al. 2011

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“…Parrish et al (2004a) argue that the increase in the North Pacific has occurred in response to increasing Asian emissions of O 3 precursors, which are transported to the North Pacific troposphere. However, other investigators (Oltmans et al, 2006(Oltmans et al, , 2008 have suggested that the reported increase at the North American west coast was actually caused by local North American continental effects rather than representing an increase in the background marine O 3 . A resolution to this disagreement is important for establishing the confidence that can be attached to the reported marine O 3 trends.…”

Section: Introductionmentioning

confidence: 94%

Increasing ozone in marine boundary layer inflow at the west coasts of North America and Europe

2009

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Abstract. An effective method is presented for determining the ozone (O 3 ) mixing ratio in the onshore flow of marine air at the North American west coast. By combining the data available from all marine boundary layer (MBL) sites with simultaneous wind data, decadal temporal trends of MBL O 3 in all seasons are established with high precision. The average springtime temporal trend over the past two decades is 0.46 ppbv/yr with a 95% confidence limit of 0.13 ppbv/yr, and statistically significant trends are found for all seasons except autumn, which does have a significantly smaller trend than other seasons. The average trend in mean annual ozone is 0.34±0.09 ppbv/yr. These decadal trends at the North American west coast present a striking comparison and contrast with the trends reported for the European west coast at Mace Head, Ireland. The trends in the winter, spring and summer seasons compare well at the two locations, while the Mace Head trend is significantly greater in autumn. Even though the trends are similar, the absolute O 3 mixing ratios differ markedly, with the marine air arriving at Europe in all seasons containing 7±2 ppbv higher ozone than marine air arriving at North America. Further, the ozone mixing ratios at the North American west coast show no indication of stabilizing as has been reported for Mace Head. In a larger historical context the background boundary layer O 3 mixing ratios over the 130 years covered by available data have increased substantially (by a factor of two to three), and this increase continues at present, at least in the MBL of the Pacific coast region of North America. The reproduction of the increasing trends in MBL O 3 over the past two decades, as well as the difference in the O 3 mixing ratios between the Correspondence to: D. D. Parrish (david.d.parrish@noaa.gov) two coastal regions will present a significant challenge for global chemical transport models. Further, the ability of the models to at least semi-quantitatively reproduce the longerterm, historical trends may an even greater challenge.

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“…(Delene and Ogren, 2002;Sherman et al, 2015 Marine site on the northern California coast, with Pacific Ocean to the west and redwood forests to the east. Though maritime airflow is predominant, some anthropogenic influences from other airflows is observed (Oltmans et al, 2008 High-altitude station located on the dry, arid Tibetan Plateau in China. The site experiences clean or dusty air masses coming in from the west and anthropogenically influenced and polluted air masses coming from the east (Kivekäs et al, 2009;Che et al, 2011).…”

Section: Site Descriptionsmentioning

confidence: 99%

Classifying aerosol type using in situ surface spectral aerosol optical properties

et al. 2017

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Abstract. Knowledge of aerosol size and composition is important for determining radiative forcing effects of aerosols, identifying aerosol sources and improving aerosol satellite retrieval algorithms. The ability to extrapolate aerosol size and composition, or type, from intensive aerosol optical properties can help expand the current knowledge of spatiotemporal variability in aerosol type globally, particularly where chemical composition measurements do not exist concurrently with optical property measurements. This study uses medians of the scattering Ångström exponent (SAE), absorption Ångström exponent (AAE) and single scattering albedo (SSA) from 24 stations within the NOAA/ESRL Federated Aerosol Monitoring Network to infer aerosol type using previously published aerosol classification schemes.Three methods are implemented to obtain a best estimate of dominant aerosol type at each station using aerosol optical properties. The first method plots station medians into an AAE vs. SAE plot space, so that a unique combination of intensive properties corresponds with an aerosol type. The second typing method expands on the first by introducing a multivariate cluster analysis, which aims to group stations with similar optical characteristics and thus similar dominantPublished by Copernicus Publications on behalf of the European Geosciences Union. L. Schmeisser et al.: Classifying aerosols with optical propertiesaerosol type. The third and final classification method pairs 3-day backward air mass trajectories with median aerosol optical properties to explore the relationship between trajectory origin (proxy for likely aerosol type) and aerosol intensive parameters, while allowing for multiple dominant aerosol types at each station.The three aerosol classification methods have some common, and thus robust, results. In general, estimating dominant aerosol type using optical properties is best suited for site locations with a stable and homogenous aerosol population, particularly continental polluted (carbonaceous aerosol), marine polluted (carbonaceous aerosol mixed with sea salt) and continental dust/biomass sites (dust and carbonaceous aerosol); however, current classification schemes perform poorly when predicting dominant aerosol type at remote marine and Arctic sites and at stations with more complex locations and topography where variable aerosol populations are not well represented by median optical properties. Although the aerosol classification methods presented here provide new ways to reduce ambiguity in typing schemes, there is more work needed to find aerosol typing methods that are useful for a larger range of geographic locations and aerosol populations.

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Background ozone levels of air entering the west coast of the US and assessment of longer-term changes

Cited by 105 publications

References 19 publications

Interannual variability of ozone and carbon monoxide at the Whistler high elevation site: 2002–2006

Interannual variability of ozone and carbon monoxide at the Whistler high elevation site: 2002–2006

Increasing ozone in marine boundary layer inflow at the west coasts of North America and Europe

Classifying aerosol type using in situ surface spectral aerosol optical properties

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