Urban eddy covariance measurements reveal significant missing NOx emissions in Central Europe

Karl, T.; Graus, M.; Striednig, Marcus; Lamprecht, Christian; Hammerle, Albin; Wohlfahrt, Georg; Held, Alexander; Heyden, Lisa von der; Deventer, M. J.; Krismer, A.; Haun, C.; Feichter, R.; Lee, James

doi:10.1038/s41598-017-02699-9

Cited by 41 publications

(36 citation statements)

References 58 publications

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“…With the exception of NO 2 which is likely bimodal in its AM-PM concentration distribution, pollutant levels trended higher in the later hours of the day (after 12 PM) aligning with previous studies as it relates to traffic pollution [83][84][85]. Diurnal significance would however diminish in constructed models.…”

Section: Discussionsupporting

confidence: 85%

Ambient air pollution per specific land use types and activities in an urbanizing Eastern Caribbean Country, St. Kitts and Nevis

Whittaker

Deziel

Zhang

et al. 2020

Environ. Res. Commun.

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Urban development can have negative impacts on the environment through various mechanisms. While many air quality studies have been carried out in more developed nations, Eastern Caribbean (EC) countries remain understudied. This study aims to estimate the concentrations of air pollutants in the EC nation of St. Kitts and Nevis. Transport, recreation and construction sites were selected randomly using local land use records. Pollutant levels were measured repeatedly for numerous 1-hour intervals in each location between October 2015 and November 2018. Weather trends and land use characteristics were collected concurrent to sampling. Across 27 sites, mean NO 2 , O 3 , SO 2 , PM 10 and PM 2.5 levels were 26.61 ppb (range: 0-306 ppb), 11.94 ppb (0-230 ppb), 27.9 ppb (0-700 ppb), 52.9 μg m −3 (0-10,400 μg m −3 ) and 29.8 μg m −3 (0-1556 μg m −3 ), respectively. Pollutants were elevated in high urban areas and generally significantly positively correlated with each other, with the exception of PM 10 . NO 2 levels in construction areas were generally comparable to those in transportation areas and higher than in recreation areas. O 3 levels were lower in construction than recreation and transport areas. SO 2 concentrations were lower in construction and recreation compared to transport sites. Construction and recreation PM 10 levels exceeded transport sites, while PM 2.5 was highest in construction areas. Additional bivariate and multivariate analysis were conducted to assess whether various meteorological, temporal and land use factors including rain, tour season and urban features explained variability in air pollutant concentrations. Tourist season and specific months, more than any other factors, contributed most to variability in pollutant concentrations. These new measurements of air pollution concentrations in an understudied nation may have important implications for health outcomes among exposed EC residents, and provide critical data for future exposure and epidemiologic research and environmental policy.

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Section: Discussionsupporting

confidence: 85%

Ambient air pollution per specific land use types and activities in an urbanizing Eastern Caribbean Country, St. Kitts and Nevis

Whittaker

Deziel

Zhang

et al. 2020

Environ. Res. Commun.

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“…According to Anenberg et al (2017), also the heavy-duty diesel trucks and buses emit more NO x than the legislative limit. Furthermore, Vaughan et al (2016) and Karl et al (2017) reached similar conclusions by analyzing NO x flux measurements and attributed the discrepancy between observations and emission inventory estimates to the underrepresentation of the real-world road traffic emissions. Moreover, a general underestimation of the total NO x emissions, compared to TNO MEGAPOLI and MACC-III inventories, by a factor of 1.4-1.5 for the summer of 2009 in Paris was recently reported by Shaiganfar et al (2017), where they used a large set of car multi-axis differential optical absorption spectroscopy (MAX-DOAS) measurements to calculate the NO x emissions by applying the closed integral method (CIM).…”

Section: Emissionsmentioning

confidence: 52%

Low modeled ozone production suggests underestimation of precursor emissions (especially NO<sub><i>x</i></sub>) in Europe

et al. 2018

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Abstract. High surface ozone concentrations, which usually occur when photochemical ozone production takes place, pose a great risk to human health and vegetation. Air quality models are often used by policy makers as tools for the development of ozone mitigation strategies. However, the modeled ozone production is often not or not enough evaluated in many ozone modeling studies. The focus of this work is to evaluate the modeled ozone production in Europe indirectly, with the use of the ozone-temperature correlation for the summer of 2010 and to analyze its sensitivity to precursor emissions and meteorology by using the regional air quality model, the Comprehensive Air Quality Model with Extensions (CAMx). The results show that the model significantly underestimates the observed high afternoon surface ozone mixing ratios (≥ 60 ppb) by 10-20 ppb and overestimates the lower ones (< 40 ppb) by 5-15 ppb, resulting in a misleading good agreement with the observations for average ozone. The model also underestimates the ozone-temperature regression slope by about a factor of 2 for most of the measurement stations. To investigate the impact of emissions, four scenarios were tested: (i) increased volatile organic compound (VOC) emissions by a factor of 1.5 and 2 for the anthropogenic and biogenic VOC emissions, respectively, (ii) increased nitrogen oxide (NO x ) emissions by a factor of 2, (iii) a combination of the first two scenarios and (iv) increased trafficonly NO x emissions by a factor of 4. For southern, eastern, and central (except the Benelux area) Europe, doubling NO x emissions seems to be the most efficient scenario to reduce the underestimation of the observed high ozone mixing ratios without significant degradation of the model performance for the lower ozone mixing ratios. The model performance for ozone-temperature correlation is also better when NO x emissions are doubled. In the Benelux area, however, the third scenario (where both NO x and VOC emissions are increased) leads to a better model performance. Although increasing only the traffic NO x emissions by a factor of 4 gave very similar results to the doubling of all NO x emissions, the first scenario is more consistent with the uncertainties reported by other studies than the latter, suggesting that high uncertainties in NO x emissions might originate mainly from the road-transport sector rather than from other sectors. The impact of meteorology was examined with three sensitivity tests: (i) increased surface temperature by 4 • C, (ii) reduced wind speed by 50 % and (iii) doubled wind speed. The first two scenarios led to a consistent increase in all surface ozone mixing ratios, thus improving the model performance for the high ozone values but significantly degrading it for the low ozone values, while the third scenario had exactly the opposite effects. Overall, the modeled ozone is predicted to be more sensitive to its precursor emissions (especially traffic NO x ) and therefore their uncertainties, which seem to be responsible for the model un...

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“…The black line shows the calculated NO x /CO 2 ratio based on the traffic count data and the emission factors according to HBEFA for stop-and-go traffic recent urban eddy covariance measurements in Innsbruck, Austria. Over a period of 1 year, the observed traffic-related NO x emissions were 50 to 70% higher than those calculated with various up-to-date emission models (Karl et al 2017). Overall, the widespread application of defeat devices is a probable cause for insufficient agreement between in situ measurements and models based on emission databases.…”

Section: No X /Co 2 Ratiosmentioning

confidence: 87%

Real-world vehicle emissions as measured by in situ analysis of exhaust plumes

Peitzmeier

Loschke

Wiedenhaus

et al. 2017

Environ Sci Pollut Res

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We conducted a 60-day roadside measurement campaign on a busy street in Münster, Germany, during summer 2016. We used gas and particle concentration measurements with high temporal resolution (10 Hz) to quantify both the emission ratios of nitrogen oxides per carbon dioxide (NO x /CO 2 ) for over 70,000 individual exhaust plumes as well as the emission ratios for size-resolved particle numbers per carbon dioxide (d(PN CO 2 −1 )/dlogD) for about 10,000plumes. The real-world fleet passing by the measurement station consisted of passenger cars (85%), buses (5.9%), light duty commercial vehicles (5.7%), trucks (1.7%), and motorcycles (1.6%). The median measured NO x /CO 2 ratio was 3.33 g kg −1 . The median measured PN/CO 2 emission ratio for particles with diameters between 0.03 and 10 μm was 5.6 × 10 14 kg −1 . We compared our results with the Handbook Emission Factors for Road Transport (HBEFA) and the Euro 5 and Euro 6 emission standards by employing traffic counts, assuming the diesel-to-gasoline ratios of vehicles according to registration statistics, and estimating that stop-and-go traffic occurred 65% of the time. Using a conservative estimate, our median ratios exceeded the HBEFA data by more than 65% for NO x /CO and by a factor of about 100 for PN/CO 2. Furthermore, our median NO x emission per kilometer travelled (NO x km −1 ) exceeded the Euro 5 emission limit for diesel cars by a factor of 3 and exceeded the Euro 6 limit by almost a factor of 7. Additionally, our median particle number emission (PN km −1 ) exceeded the Euro 5 and Euro 6 limits of diesel cars by a factor of almost 150. These results confirm the presumption that the emissions of a real-world traffic fleet comprehensively exceed the legal limits. Very likely, the widespread presence of defeat devices in vehicle emission control systems plays a major role in this discrepancy. This has a strong impact on the apparent inability of authorities to comply with the legal limits of the NO 2 concentrations in urban air.

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Urban eddy covariance measurements reveal significant missing NOx emissions in Central Europe

Cited by 41 publications

References 58 publications

Ambient air pollution per specific land use types and activities in an urbanizing Eastern Caribbean Country, St. Kitts and Nevis

Ambient air pollution per specific land use types and activities in an urbanizing Eastern Caribbean Country, St. Kitts and Nevis

Low modeled ozone production suggests underestimation of precursor emissions (especially NO<sub><i>x</i></sub>) in Europe

Real-world vehicle emissions as measured by in situ analysis of exhaust plumes

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Urban eddy covariance measurements reveal significant missing NOx emissions in Central Europe

Cited by 41 publications

References 58 publications

Ambient air pollution per specific land use types and activities in an urbanizing Eastern Caribbean Country, St. Kitts and Nevis

Ambient air pollution per specific land use types and activities in an urbanizing Eastern Caribbean Country, St. Kitts and Nevis

Low modeled ozone production suggests underestimation of precursor emissions (especially NO&lt;sub&gt;&lt;i&gt;x&lt;/i&gt;&lt;/sub&gt;) in Europe

Real-world vehicle emissions as measured by in situ analysis of exhaust plumes

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Low modeled ozone production suggests underestimation of precursor emissions (especially NO<sub><i>x</i></sub>) in Europe