Measured and modeled CO and NO y in DISCOVER-AQ: An evaluation of emissions and chemistry over the eastern US

Anderson, Daniel C.; Loughner, Christopher P.; Diskin, G. S.; Weinheimer, A. J.; Canty, T. P.; Salawitch, R. J.; Worden, H. M.; Fried, Alan; Mikoviny, Tomáš; Wisthaler, Armin; Dickerson, Russell R.

doi:10.1016/j.atmosenv.2014.07.004

Cited by 121 publications

(163 citation statements)

References 31 publications

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“…3.1. This adjustment is also consistent with recent estimates of NO x emissions over the Southeast US (Anderson et al, 2014). The resulting anthropogenic NO x emissions (0.25 Tg N month −1 ) are 14 % lower than the 2011 EPA national emission inventory (NEI11v1) estimate of 0.29 Tg N month −1 (0.28 Tg N month −1 from the updated NEI11v2 emission inventory), although both inventories have a similar spatial distribution (Fig.…”

Section: Am3 Modelsupporting

confidence: 76%

Decadal changes in summertime reactive oxidized nitrogen and surface ozone over the Southeast United States

Mao

Fiore

et al. 2018

Atmos. Chem. Phys.

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Published by Copernicus Publications on behalf of the European Geosciences Union. 2342 J. Li et al.: Decadal changes in summertime reactive oxidized nitrogen and surface ozone Abstract. Widespread efforts to abate ozone (O 3 ) smog have significantly reduced emissions of nitrogen oxides (NO x ) over the past 2 decades in the Southeast US, a place heavily influenced by both anthropogenic and biogenic emissions. How reactive nitrogen speciation responds to the reduction in NO x emissions in this region remains to be elucidated. Here we exploit aircraft measurements from ICARTT (JulyAugust 2004), SENEX (June-July 2013), and SEAC 4 RS (August-September 2013) and long-term ground measurement networks alongside a global chemistry-climate model to examine decadal changes in summertime reactive oxidized nitrogen (RON) and ozone over the Southeast US. We show that our model can reproduce the mean vertical profiles of major RON species and the total (NO y ) in both 2004 and 2013. Among the major RON species, nitric acid (HNO 3 ) is dominant (∼ 42-45 %), followed by NO x (31 %), total peroxy nitrates ( PNs; 14 %), and total alkyl nitrates ( ANs; 9-12 %) on a regional scale. We find that most RON species, including NO x , PNs, and HNO 3 , decline proportionally with decreasing NO x emissions in this region, leading to a similar decline in NO y . This linear response might be in part due to the nearly constant summertime supply of biogenic VOC emissions in this region. Our model captures the observed relative change in RON and surface ozone from 2004 to 2013. Model sensitivity tests indicate that further reductions of NO x emissions will lead to a continued decline in surface ozone and less frequent high-ozone events.

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Section: Am3 Modelsupporting

confidence: 76%

Decadal changes in summertime reactive oxidized nitrogen and surface ozone over the Southeast United States

Mao

Fiore

et al. 2018

Atmos. Chem. Phys.

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“…NO x concentrations at Essex (20 km ENE of UMBC) and HU-Beltsville (35 km SSW of UMBC) are strongly correlated (R = 0.89, Fig. S1 in the Supplement), likely due to the overwhelming contribution of mobile source emissions along the heavily traveled I-95 highway corridor to the region (Anderson et al, 2014). Together, this supports our analysis into the effects of isoprene and NO x on reversible aqSOA using the measurements described above.…”

Section: Voc and No X Measurementssupporting

confidence: 73%

The effects of isoprene and NO<sub><i>x</i></sub> on secondary organic aerosols formed through reversible and irreversible uptake to aerosol water

2018

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Abstract. Isoprene oxidation produces water-soluble organic gases capable of partitioning to aerosol liquid water. The formation of secondary organic aerosols through such aqueous pathways (aqSOA) can take place either reversibly or irreversibly; however, the split between these fractions in the atmosphere is highly uncertain. The aim of this study was to characterize the reversibility of aqSOA formed from isoprene at a location in the eastern United States under substantial influence from both anthropogenic and biogenic emissions. The reversible and irreversible uptake of water-soluble organic gases to aerosol water was characterized in Baltimore, Maryland, USA, using measurements of particulate water-soluble organic carbon (WSOC p ) in alternating dry and ambient configurations. WSOC p evaporation with drying was observed systematically throughout the late spring and summer, indicating reversible aqSOA formation during these times. We show through time lag analyses that WSOC p concentrations, including the WSOC p that evaporates with drying, peak 6 to 11 h after isoprene concentrations, with maxima at a time lag of 9 h. The absolute reversible aqSOA concentrations, as well as the relative amount of reversible aq-SOA, increased with decreasing NO x / isoprene ratios, suggesting that isoprene epoxydiol (IEPOX) or other low-NO x oxidation products may be responsible for these effects. The observed relationships with NO x and isoprene suggest that this process occurs widely in the atmosphere, and is likely more important in other locations characterized by higher isoprene and/or lower NO x levels. This work underscores the importance of accounting for both reversible and irreversible uptake of isoprene oxidation products to aqueous particles.

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“…Scaling factors were applied to all emitted chemical species to represent anthropogenic emissions in the year 2013 using the ratio of national annual totals [30]. Recent studies have shown that NO x emissions from sources other than power plants (i.e., mobile sources) in this inventory, which contribute significantly to total NO x emissions, are overestimated and in this study the NEI emission rates are reduced by 50% similar to many recent studies (e.g., [29,[31][32][33][34]). …”

Section: Geos-chem Modelsupporting

confidence: 61%

Evaluating Summer-Time Ozone Enhancement Events in the Southeast United States

et al. 2016

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This study evaluates source attribution of ozone (O 3 ) in the southeast United States (US) within O 3 lamina observed by the University of Alabama in Huntsville (UAH) Tropospheric Ozone Lidar Network (TOLNet) system during June 2013. This research applies surface-level and airborne in situ data and chemical transport model simulations (GEOS-Chem) in order to quantify the impact of North American anthropogenic emissions, wildfires, lightning NO x , and long-range/stratospheric transport on the observed O 3 lamina. During the summer of 2013, two anomalous O 3 layers were observed: (1) a nocturnal near-surface enhancement and (2) a late evening elevated (3-6 km above ground level) O 3 lamina. A "brute force" zeroing method was applied to quantify the impact of individual emission sources and transport pathways on the vertical distribution of O 3 during the two observed lamina. Results show that the nocturnal O 3 enhancement on 12 June 2013 below 3 km was primarily due to wildfire emissions and the fact that daily maximum anthropogenic emission contributions occurred during these night-time hours. During the second case study it was predicted that above average contributions from long-range/stratospheric transport was largely contributing to the O 3 lamina observed between 3 and 6 km on 29 June 2013. Other models, remote-sensing observations, and ground-based/airborne in situ data agree with the source attribution predicted by GEOS-Chem simulations. Overall, this study demonstrates the dynamic atmospheric chemistry occurring in the southeast US and displays the various emission sources and transport processes impacting O 3 enhancements at different vertical levels of the troposphere.

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Measured and modeled CO and NO y in DISCOVER-AQ: An evaluation of emissions and chemistry over the eastern US

Cited by 121 publications

References 31 publications

Decadal changes in summertime reactive oxidized nitrogen and surface ozone over the Southeast United States

Decadal changes in summertime reactive oxidized nitrogen and surface ozone over the Southeast United States

The effects of isoprene and NO<sub><i>x</i></sub> on secondary organic aerosols formed through reversible and irreversible uptake to aerosol water

Evaluating Summer-Time Ozone Enhancement Events in the Southeast United States

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Measured and modeled CO and NO y in DISCOVER-AQ: An evaluation of emissions and chemistry over the eastern US

Cited by 121 publications

References 31 publications

Decadal changes in summertime reactive oxidized nitrogen and surface ozone over the Southeast United States

Decadal changes in summertime reactive oxidized nitrogen and surface ozone over the Southeast United States

The effects of isoprene and NO&lt;sub&gt;&lt;i&gt;x&lt;/i&gt;&lt;/sub&gt; on secondary organic aerosols formed through reversible and irreversible uptake to aerosol water

Evaluating Summer-Time Ozone Enhancement Events in the Southeast United States

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The effects of isoprene and NO<sub><i>x</i></sub> on secondary organic aerosols formed through reversible and irreversible uptake to aerosol water