Cities, traffic, and CO
 2
 : A multidecadal assessment of trends, drivers, and scaling relationships

Gately, C.; Hutyra, Lucy R.; Wing, Ian Sue

doi:10.1073/pnas.1421723112

Cited by 136 publications

(105 citation statements)

References 25 publications

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“…Ackerman and Sundquist (2008), for example, compare smokestack versus fuel-based CO 2 estimates for US power plants and find a mean absolute difference of 16.6 % but only a 1.4 % total difference at the national scale. Furthermore, Gately et al (2015) find biases of 100 % or more at the urban scale in CO 2 emission estimates for mobile sources. However, they estimate a US national total that is broadly consistent with other inventories like VULCAN.…”

Section: Impact Of Recent Advancesmentioning

confidence: 93%

“…State and national governments in the US use this strategy to construct official emission estimates (e.g., California Air Resources Board, 2015; US EPA, 2016c). A number of academic and government efforts have produced bottom-up CO 2 and CH 4 emission estimates at local-regional (e.g., Gately et al, 2013;Jeong et al, 2014;Lyon et al, 2015;California Air Resources Board, 2015), national (e.g., Pétron et al, 2008;Gurney et al, 2009;Gately et al, 2015;US EPA, 2013;Environment and Climate Change Canada, 2016;Maasakkers et al, 2016), and global scales (e.g., Rayner et al, 2010;Andres et al, 2011;Oda and Maksyutov, 2011;Olivier et al, 2014;EC JRC/PBL, 2016). In this section, we primarily discuss bottom-up data with an eye toward how this information can be combined with top-down strategies.…”

Section: Bottom-up Datamentioning

confidence: 99%

“…The authors explain that many global-scale efforts use road density as a proxy for vehicle emissions but argue that the relationship between road density and emissions is not constant. Two subsequent studies (McDonald et al, 2014;Gately et al, 2015) estimate on-road CO 2 emissions for the entire US at spatial resolutions down to 1 km 2 . McDonald et al's 2014 emission estimates differ from EDGAR by 20-80 % at the municipal level, though the two inventories produce nearly identical national totals.…”

Section: Recent Bottom-up Effortsmentioning

confidence: 99%

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Constraining sector-specific CO2 and CH4 emissions in the US

Miller

Michalak

2017

Atmos. Chem. Phys.

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Abstract. This review paper explores recent efforts to estimate state-and national-scale carbon dioxide (CO 2 ) and methane (CH 4 ) emissions from individual anthropogenic source sectors in the US. Nearly all state and national climate change regulations in the US target specific source sectors, and detailed monitoring of individual sectors presents a greater challenge than monitoring total emissions. We particularly focus on opportunities to synthesize disparate types of information on emissions, including emission inventory data and atmospheric greenhouse gas data.We find that inventory estimates of sector-specific CO 2 emissions are sufficiently accurate for policy evaluation at the national scale but that uncertainties increase at state and local levels. CH 4 emission inventories are highly uncertain for all source sectors at all spatial scales, in part because of the complex, spatially variable relationships between economic activity and CH 4 emissions. In contrast to inventory estimates, top-down estimates use measurements of atmospheric mixing ratios to infer emissions at the surface; thus far, these efforts have had some success identifying urban CO 2 emissions and have successfully identified sector-specific CH 4 emissions in several opportunistic cases. We also describe a number of forward-looking opportunities that would aid efforts to estimate sector-specific emissions: fully combine existing top-down datasets, expand intensive aircraft measurement campaigns and measurements of secondary tracers, and improve the economic and demographic data (e.g., activity data) that drive emission inventories. These steps would better synthesize inventory and topdown data to support sector-specific emission reduction policies.

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Section: Impact Of Recent Advancesmentioning

confidence: 93%

Section: Bottom-up Datamentioning

confidence: 99%

Section: Recent Bottom-up Effortsmentioning

confidence: 99%

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Constraining sector-specific CO2 and CH4 emissions in the US

Miller

Michalak

2017

Atmos. Chem. Phys.

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“…This ratio approach is considered to be a robust method for estimating on-road NH 3 emissions because the uncertainty in on-road CO 2 emissions is much less than for estimates of on-road NH 3 emissions (Sun et al, 2017). On-road CO 2 emissions used to calculate on-road NH 3 emissions were obtained from the Database of Road Transportation Emissions (DARTE) (DARTE, 2017;Gately et al, 2015;USEPA, 2017). DARTE is an annual 1-km grid of CO 2 emissions from 2012 using the Federal Highway Administration's Highway Performance Monitoring System roadway-level vehicle miles travelled and state data.…”

Section: Ammonia Emissions Datamentioning

confidence: 99%

On-road emissions of ammonia: An underappreciated source of atmospheric nitrogen deposition

Fenn

Bytnerowicz

Schilling

et al. 2018

Science of The Total Environment

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H I G H L I G H T S• This study documents the increasing importance of on-road emissions of NH 3.• NO x emissions control mechanisms frequently result in NH 3 production and emissions.• NH 3 is an important driver of N deposition in urban-affected areas and near roadways.• NH 4 -N:NO 3 -N ratios in urban deposition are indicative of elevated NH 3 emissions.• On-road NH 3 emissions exceed agricultural emissions where 40% of the U.S. resides. We provide updated spatial distribution and inventory data for on-road NH 3 emissions for the continental United States (U.S.) On-road NH 3 emissions were determined from on-road CO 2 emissions data and empirical NH 3 :CO 2 vehicle emissions ratios. Emissions of NH 3 from on-road sources in urbanized regions are typically 0.1-1.3 t km −2 yr −1 while NH 3 emissions in agricultural regions generally range from 0.4-5.5 t km G R A P H I C A L A B S T R A C T a b s t r a c t a r t i c l e i n f o, with a few hotspots as high as 5.5-11.2 t km −2 yr −1. Counties with higher vehicle NH 3 emissions than from agriculture include 40% of the U.S. population. The amount of wet inorganic N deposition as NH 4 + from the National Atmospheric Deposition Program (NADP) network ranged from 37 to 83% with a mean of 58.7%. Only 4% of the NADP sites across the U.S. had b45% of the N deposition as NH 4 + based on data from 2014 to 2016, illustrating the near-universal elevated proportions of NH 4 + in deposition across the U.S. Case studies of on-road NH 3 emissions in relation to N deposition include four urban sites in Oregon and Washington where the average NH 4 -N:NO 3 -N ratio in bulk deposition was 2.3. At urban sites in the greater Los Angeles Basin, bulk deposition of NH 4 -N and NO 3 -N were equivalent, while NH 4 -N:NO 3 -N in throughfall under shrubs ranged from 0.6 to 1.7. The NH 4 -N:NO 3 -N ratio at 7-10 sites in the Lake Tahoe Basin averaged 1.4 and 1.6 in bulk deposition and throughfall, and deposition of NH 4 -N was strongly correlated with summertime NH 3 concentrations. On-road

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“…5 and 6), recent satellite images taken during 2012-2015 (Fig. 3), and current photographs taken during the site visits in 2015 and2016 (Fig. 9).…”

Section: Data Related To Urbanizationmentioning

confidence: 99%

Is global dimming and brightening in Japan limited to urban areas?

et al. 2016

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Abstract. Worldwide observations indicate secular trends of all-sky surface solar radiation on a decadal time scale, termed global dimming and brightening. Accordingly, the observed surface radiation in Japan generally shows a strong decline until the end of the 1980s and then a recovery until around 2000. Because a substantial number of measurement stations are located within or close to populated areas, one may speculate that the observed trends are strongly influenced by local air pollution and are thus not of large-scale significance. This hypothesis poses a serious question as to what regional extent the global dimming and brightening are significant: are the global dimming and brightening truly global phenomena, or regional, or even only local? Our study focused on 14 meteorological observatories that measured all-sky surface solar radiation, zenith transmittance, and maximum transmittance. On the basis of municipality population time series, historical land use maps, recent satellite images, and actual site visits, we concluded that eight stations have been significantly influenced by urbanization, with the remaining six stations being left pristine. Between the urban and rural areas, no marked differences were identified in the temporal trends of the aforementioned meteorological parameters. Our findings suggest that global dimming and brightening in Japan occurred on a large scale, independently of urbanization.

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Cities, traffic, and CO ₂ : A multidecadal assessment of trends, drivers, and scaling relationships

Cited by 136 publications

References 25 publications

Constraining sector-specific CO<sub>2</sub> and CH<sub>4</sub> emissions in the US

Constraining sector-specific CO<sub>2</sub> and CH<sub>4</sub> emissions in the US

On-road emissions of ammonia: An underappreciated source of atmospheric nitrogen deposition

Is global dimming and brightening in Japan limited to urban areas?

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Cities, traffic, and CO 2 : A multidecadal assessment of trends, drivers, and scaling relationships

Cited by 136 publications

References 25 publications

Constraining sector-specific CO&lt;sub&gt;2&lt;/sub&gt; and CH&lt;sub&gt;4&lt;/sub&gt; emissions in the US

Constraining sector-specific CO&lt;sub&gt;2&lt;/sub&gt; and CH&lt;sub&gt;4&lt;/sub&gt; emissions in the US

On-road emissions of ammonia: An underappreciated source of atmospheric nitrogen deposition

Is global dimming and brightening in Japan limited to urban areas?

Contact Info

Product

Resources

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Cities, traffic, and CO ₂ : A multidecadal assessment of trends, drivers, and scaling relationships

Constraining sector-specific CO<sub>2</sub> and CH<sub>4</sub> emissions in the US

Constraining sector-specific CO<sub>2</sub> and CH<sub>4</sub> emissions in the US