scholarly journals Impacts of the Denver Cyclone on regional air quality and aerosol formation in the Colorado Front Range during FRAPPÉ 2014

2016 ◽  
Vol 16 (18) ◽  
pp. 12039-12058 ◽  
Author(s):  
Kennedy T. Vu ◽  
Justin H. Dingle ◽  
Roya Bahreini ◽  
Patrick J. Reddy ◽  
Eric C. Apel ◽  
...  
Keyword(s):  
Air Quality ◽  
Metropolitan Area ◽  
Chemical Constituents ◽  
Organic Aerosols ◽  
Front Range ◽  
Aerosol Formation ◽  
Optical Extinction ◽  
Airborne Measurements ◽  
Regional Air Quality ◽  
Mass Concentrations

Abstract. We present airborne measurements made during the 2014 Front Range Air Pollution and Photochemistry Experiment (FRAPPÉ) project to investigate the impacts of the Denver Cyclone on regional air quality in the greater Denver area. Data on trace gases, non-refractory submicron aerosol chemical constituents, and aerosol optical extinction (βext) at λ  =  632 nm were evaluated in the presence and absence of the surface mesoscale circulation in three distinct study regions of the Front Range: In-Flow, Northern Front Range, and the Denver metropolitan area. Pronounced increases in mass concentrations of organics, nitrate, and sulfate in the Northern Front Range and the Denver metropolitan area were observed during the cyclone episodes (27–28 July) compared to the non-cyclonic days (26 July, 2–3 August). Organic aerosols dominated the mass concentrations on all evaluated days, with a 45 % increase in organics on cyclone days across all three regions, while the increase during the cyclone episode was up to  ∼  80 % over the Denver metropolitan area. In the most aged air masses (NOx / NOy  <  0.5), background organic aerosols over the Denver metropolitan area increased by a factor of ∼  2.5 due to transport from Northern Front Range. Furthermore, enhanced partitioning of nitric acid to the aerosol phase was observed during the cyclone episodes, mainly due to increased abundance of gas phase ammonia. During the non-cyclone events, βext displayed strong correlations (r  =  0.71) with organic and nitrate in the Northern Front Range and only with organics (r  =  0.70) in the Denver metropolitan area, while correlation of βext during the cyclone was strongest (r  =  0.86) with nitrate over Denver. Mass extinction efficiency (MEE) values in the Denver metropolitan area were similar on cyclone and non-cyclone days despite the dominant influence of different aerosol species on βext. Our analysis showed that the meteorological patterns associated with the Denver Cyclone increased aerosol mass loadings in the Denver metropolitan area mainly by transporting aerosols and/or aerosol precursors from the northern regions, leading to impaired visibility and air quality deterioration.

scholarly journals Impacts of the Denver Cyclone on Regional Air Quality and Aerosol Formation in the Colorado Front Range during FRAPPÉ 2014

2016 ◽  
Author(s):  
Kennedy T. Vu ◽  
Justin H. Dingle ◽  
Roya Bahreini ◽  
Patrick J. Reddy ◽  
Teresa L. Campos ◽  
...  
Keyword(s):  
Chemical Constituents ◽  
Circulation Pattern ◽  
Colorado Front Range ◽  
Front Range ◽  
Aerosol Formation ◽  
Optical Extinction ◽  
Airborne Measurements ◽  
Aerosol Optical Extinction ◽  
Project Data ◽  
Mass Concentrations

Abstract. We present airborne measurements made in the Colorado Front Range aboard the NSF C-130 aircraft during the 2014 Front Range Air Pollution and Photochemistry Éxperiment (FRAPPÉ) project. Data on trace gases, non-refractory sub-micron aerosol chemical constituents, and aerosol optical extinction (βext) at λ = 632 nm in the presence and absence of a surface mesoscale circulation pattern, called the Denver Cyclone, were analyzed in three study regions of the Front Range: In-Flow, Northern Front Range (NFR), and Denver Metropolitan (DM). Pronounced increases in mass concentrations of organics, nitrate, and sulfate in NFR and DM were observed during the cyclone episodes (27–28 July) compared to the non-cyclonic days (26 July, 02–03 August). Organics (OA) dominated the mass concentrations on all evaluated days, with a 45 % increase in OA on cyclone days across all three regions while the increase during the cyclone episode was up to ~ 80 % for DM, from 3.78 ± 1.55 µg sm−3 to 6.78 ± 1.78 µg sm−3, where sm−3 is the STP unit of volume of air. Average nitrate mass concentrations were 0.26 ± 0.27 µg sm−3 vs. 1.03 ± 0.74 µg sm−3 followed by sulfate with an average of 0.58 ± 0.23 µg sm−3 vs. 1.08 ± 0.73 µg sm−3 on non-cyclone vs. cyclonic days, respectively. In the most aged air masses (NOx/NOy 

scholarly journals Regional contributions to particulate matter concentration in the Seoul metropolitan area, South Korea: seasonal variation and sensitivity to meteorology and emissions inventory

2017 ◽  
Vol 17 (17) ◽  
pp. 10315-10332 ◽  
Author(s):  
Hyun Cheol Kim ◽  
Eunhye Kim ◽  
Changhan Bae ◽  
Jeong Hoon Cho ◽  
Byeong-Uk Kim ◽  
...  
Keyword(s):  
Particulate Matter ◽  
Seasonal Variation ◽  
Air Quality ◽  
South Korea ◽  
Metropolitan Area ◽  
Policy Support ◽  
Seoul Metropolitan Area ◽  
Regional Air Quality ◽  
Emissions Inventories ◽  
The Impact

Abstract. The impact of regional emissions (e.g., domestic and international) on surface particulate matter (PM) concentrations in the Seoul metropolitan area (SMA), South Korea, and its sensitivities to meteorology and emissions inventories are quantitatively estimated for 2014 using regional air quality modeling systems. Located on the downwind side of strong sources of anthropogenic emissions, South Korea bears the full impact of the regional transport of pollutants and their precursors. However, the impact of foreign emissions sources has not yet been fully documented. We utilized two regional air quality simulation systems: (1) a Weather Research and Forecasting and Community Multi-Scale Air Quality (CMAQ) system and (2) a United Kingdom Met Office Unified Model and CMAQ system. The following combinations of emissions inventories are used: the Intercontinental Chemical Transport Experiment-Phase B, the Inter-comparison Study for Asia 2010, and the National Institute of Environment Research Clean Air Policy Support System. Partial contributions of domestic and foreign emissions are estimated using a brute force approach, adjusting South Korean emissions to 50 %. Results show that foreign emissions contributed  ∼  60 % of SMA surface PM concentration in 2014. Estimated contributions display clear seasonal variation, with foreign emissions having a higher impact during the cold season (fall to spring), reaching  ∼  70 % in March, and making lower contributions in the summer,  ∼  45 % in September. We also found that simulated surface PM concentration is sensitive to meteorology, but estimated contributions are mostly consistent. Regional contributions are also found to be sensitive to the choice of emissions inventories.

scholarly journals Technical Note: Synthesis of isoprene atmospheric oxidation products: isomeric epoxydiols and the rearrangement products <i>cis</i>- and <i>trans</i>-3-methyl-3,4-dihydroxytetrahydrofuran

2012 ◽  
Vol 12 (6) ◽  
pp. 14247-14268
Author(s):  
Z. Zhang ◽  
Y.-H. Lin ◽  
H. Zhang ◽  
J. D. Surratt ◽  
L. M. Ball ◽  
...  
Keyword(s):  
Air Quality ◽  
Gas Phase ◽  
Good Yield ◽  
Organic Aerosols ◽  
Technical Note ◽  
Oxidation Products ◽  
Atmospheric Oxidation ◽  
Aerosol Formation ◽  
Cis And Trans ◽  
Oxidation Mechanisms

Abstract. Isoprene epoxydiol (IEPOX) isomers are key gas-phase intermediates of isoprene atmospheric oxidation. Secondary organic aerosols derived from such intermediates have important impacts on air quality and health. We report here convergent and unambiguous pathways developed for the synthesis of isomeric IEPOX species and the rearrangement products cis- and trans-3-methyl-3,4-dihydroxytetrahydrofuran in good yield. The availability of such compounds is necessary to expedite research on isoprene atmospheric oxidation mechanisms and subsequent aerosol formation as well as the toxicological properties of the aerosols.

scholarly journals Technical Note: Synthesis of isoprene atmospheric oxidation products: isomeric epoxydiols and the rearrangement products <i>cis</i>- and <i>trans</i>-3-methyl-3,4-dihydroxytetrahydrofuran

2012 ◽  
Vol 12 (18) ◽  
pp. 8529-8535 ◽  
Author(s):  
Z. Zhang ◽  
Y.-H. Lin ◽  
H. Zhang ◽  
J. D. Surratt ◽  
L. M. Ball ◽  
...  
Keyword(s):  
Air Quality ◽  
Gas Phase ◽  
Good Yield ◽  
Organic Aerosols ◽  
Technical Note ◽  
Oxidation Products ◽  
Atmospheric Oxidation ◽  
Aerosol Formation ◽  
Cis And Trans ◽  
Oxidation Mechanisms

Abstract. Isoprene epoxydiol (IEPOX) isomers are key gas-phase intermediates of isoprene atmospheric oxidation. Secondary organic aerosols derived from such intermediates have important impacts on air quality and health. We report here convergent and unambiguous pathways developed for the synthesis of isomeric IEPOX species and the rearrangement products cis- and trans-3-methyl-3,4-dihydroxytetrahydrofuran in good yield. The availability of such compounds is necessary to expedite research on isoprene atmospheric oxidation mechanisms and subsequent aerosol formation as well as the toxicological properties of the aerosols.

scholarly journals Influences of emission sources and meteorology on aerosol chemistry in a polluted urban environment: results from DISCOVER-AQ California

2015 ◽  
Vol 15 (23) ◽  
pp. 35057-35115 ◽  
Author(s):  
D. E. Young ◽  
H. Kim ◽  
C. Parworth ◽  
S. Zhou ◽  
X. Zhang ◽  
...  
Keyword(s):  
Air Quality ◽  
Solar Radiation ◽  
Mass Spectrometer ◽  
Biomass Burning ◽  
Time Of Flight ◽  
Organic Aerosols ◽  
Meteorological Conditions ◽  
Aerosol Formation ◽  
Aerosol Chemistry ◽  
Secondary Aerosol

Abstract. The San Joaquin Valley (SJV) in California experiences persistent air quality problems associated with elevated particulate matter (PM) concentrations due to anthropogenic emissions, topography, and meteorological conditions. Thus it is important to unravel the various sources and processes that affect the physico-chemical properties of PM in order to better inform pollution abatement strategies and improve parameterizations in air quality models. During January and February 2013, a ground supersite was installed at the Fresno-Garland California Air Resources Board (CARB) monitoring station, where comprehensive, real-time measurements of PM and trace gases were performed using instruments including an Aerodyne High Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-ToF-AMS) and an Ionicon Proton Transfer Reaction Time-of-Flight Mass Spectrometer (PTR-TOF-MS) as part of the NASA Deriving Information on Surface Conditions from Column and Vertically Resolved Observations Relevant to Air Quality (DISCOVER-AQ) campaign. The average submicron aerosol (PM1) concentration was 31.0 μg m−3 and the total mass was dominated by organic aerosols (OA, 55 %), followed by ammonium nitrate (35 %). High PM pollution events were commonly associated with elevated OA concentrations, mostly from primary sources. Organic aerosols had average atomic oxygen-to-carbon (O / C), hydrogen-to-carbon (H / C), and nitrogen-to-carbon (N / C) ratios of 0.42, 1.70, and 0.017, respectively. Six distinct sources of organic aerosol were identified from positive matrix factorization (PMF) analysis of the AMS data: hydrocarbon-like OA (HOA; 9 % of total OA; O / C = 0.09) associated with local traffic, cooking OA (COA; 28 % of total OA; O / C = 0.19) associated with food cooking activities, two biomass burning OAs (BBOA1; 13 % of total OA; O / C = 0.33 and BBOA2; 20 % of total OA; O / C = 0.60) most likely associated with residential space heating from wood combustion, and semi-volatile oxygenated OA (SV-OOA; 16 % of total OA; O / C = 0.63) and low volatility oxygenated OA (LV-OOA; 24 % of total OA; O / C = 0.90) formed via chemical reactions in the atmosphere. Large differences in aerosol chemistry at Fresno were observed between the current campaign (winter 2013) and a previous wintertime campaign (winter 2010), most notably that PM1 concentrations were nearly three times higher in 2013 than in 2010. These variations were attributed to differences in the meteorological conditions, which influenced primary emissions and secondary aerosol formation. In particular, COA and BBOA concentrations were greater in 2013 than 2010, where colder temperatures in 2013 likely resulted in increased biomass burning activities. The influence from a nighttime formed residual layer that mixed down in the morning was found to be much more intense in 2013 than 2010, leading to sharp increases in ground-level concentrations of secondary aerosol species including nitrate, sulfate, and OOA, in the morning between 08:00 to 12:00 PST. This is an indication that nighttime chemistry might also be higher in 2013. As solar radiation was stronger in 2013 the higher nitrate and OOA concentrations in 2013 could also be partly due to greater photochemical production of secondary aerosol species. The greater solar radiation and larger range in temperature in 2013 also likely led to both SV-OOA and LV-OOA being observed in 2013 whereas only a single OOA factor was identified in 2010.

scholarly journals Characterizing the impact of urban emissions on regional aerosol particles: airborne measurements during the MEGAPOLI experiment

2014 ◽  
Vol 14 (3) ◽  
pp. 1397-1412 ◽  
Author(s):  
E. J. Freney ◽  
K. Sellegri ◽  
F. Canonaco ◽  
A. Colomb ◽  
A. Borbon ◽  
...  
Keyword(s):  
Gas Phase ◽  
Organic Aerosol ◽  
Aerosol Formation ◽  
Air Mass ◽  
Airborne Measurements ◽  
Aerosol Mass ◽  
Urban Emissions ◽  
The Impact ◽  
The City ◽  
Mass Concentrations

Abstract. The MEGAPOLI (Megacities: Emissions, urban, regional and Global Atmospheric POLlution and climate effects, and Integrated tools for assessment and mitigation) experiment took place in July 2009. The aim of this campaign was to study the aging and reactions of aerosol and gas-phase emissions in the city of Paris. Three ground-based measurement sites and several mobile platforms including instrument equipped vehicles and the ATR-42 aircraft were involved. We present here the variations in particle- and gas-phase species over the city of Paris, using a combination of high-time resolution measurements aboard the ATR-42 aircraft. Particle chemical composition was measured using a compact time-of-flight aerosol mass spectrometer (C-ToF-AMS), giving detailed information on the non-refractory submicron aerosol species. The mass concentration of black carbon (BC), measured by a particle absorption soot photometer (PSAP), was used as a marker to identify the urban pollution plume boundaries. Aerosol mass concentrations and composition were affected by air-mass history, with air masses that spent longest time over land having highest fractions of organic aerosol and higher total mass concentrations. The Paris plume is mainly composed of organic aerosol (OA), BC, and nitrate aerosol, as well as high concentrations of anthropogenic gas-phase species such as toluene, benzene, and NOx. Using BC and CO as tracers for air-mass dilution, we observe the ratio of ΔOA / ΔBC and ΔOA / ΔCO increase with increasing photochemical age (−log(NOx / NOy)). Plotting the equivalent ratios of different organic aerosol species (LV-OOA, SV-OOA, and HOA) illustrate that the increase in OA is a result of secondary organic aerosol (SOA) formation. Within Paris the changes in the ΔOA / ΔCO are similar to those observed during other studies in London, Mexico City, and in New England, USA. Using the measured SOA volatile organic compounds (VOCs) species together with organic aerosol formation yields, we were able to predict ~50% of the measured organics. These airborne measurements during the MEGAPOLI experiment show that urban emissions contribute to the formation of OA and have an impact on aerosol composition on a regional scale.

scholarly journals Influence of Intense secondary aerosol formation and long range transport on aerosol chemistry and properties in the Seoul Metropolitan Area during spring time: Results from KORUS-AQ

2017 ◽  
Author(s):  
Hwajin Kim ◽  
Qi Zhang ◽  
Jongbae Heo
Keyword(s):  
Air Quality ◽  
Metropolitan Area ◽  
Meteorological Conditions ◽  
Photochemical Reactions ◽  
Long Range Transport ◽  
Emission Sources ◽  
Aerosol Formation ◽  
Atmospheric Processes ◽  
Seoul Metropolitan Area ◽  
Range Transport

Abstract. Non-refractory submicrometer particulate matter (NR-PM1) was measured in the Seoul Metropolitan Area (SMA), Korea, using an Aerodyne high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS) from April 14 to June 15, 2016, as a part of the Korea-U.S. Air Quality Study (KORUS-AQ) campaign. This was the first highly time-resolved, real-time measurement study of springtime aerosol in SMA and the results reveal valuable insights into the sources and atmospheric processes that contribute to PM pollution in this region. The average concentration of submicrometer aerosol (PM1 = NR-PM1 + black carbon (BC)) was 22.1 µg m−3, which was composed of 44 % organics, 20 % sulfate, 17 % nitrate, 12 % ammonium, and 7 % BC. Organics had an average atomic oxygen-to-carbon (O / C) ratio of 0.49 and an average organic mass-to-carbon (OM / OC) ratio of 1.82. The concentration and composition of PM1 varied dynamically due to the influences of different meteorological conditions, emission sources, and air mass origins. Four distinct sources of OA were identified via positive matrix factorization (PMF) analysis of the HR-ToF-AMS data: vehicle emissions represented by a hydrocarbon like OA factor (HOA; O / C = 0.15; 17 % of OA mass), cooking activities represented by a cooking OA factor (COA; O / C = 0.19; 22 % of OA mass), and secondary organic aerosol (SOA) represented by a semi-volatile oxygenated OA factor (SV-OOA; O / C = 0.44; 27 % of OA mass) and a low volatility oxygenated OA factor (LV-OOA; O / C = 0.91; 34 % of OA mass). Our results indicate that air quality in SMA during KORUS-AQ was influenced strongly by secondary aerosol formation with sulfate, nitrate, ammonium, SV-OOA, and LV-OOA together accounting for 76 % of the PM1 mass. In particular, high temperature, elevated ozone concentrations, and photochemical reactions during daytime promoted the formation of SV-OOA, LV-OOA and sulfate whereas nocturnal processing of nitrogen oxides and daytime photochemical reactions promoted nitrate formation. In addition, gas-to-particle partitioning processes appeared to have enhanced nighttime SV-OOA and nitrate formation. During a period of 4 days (from May 20 to May 23), LV-OOA was significantly enhanced and accounted for up to 41 % of the PM1 mass. This intense LV-OOA formation event was associated with large enhancements of both anthropogenic and biogenic VOCs (e.g., isoprene, toluene), high concentration of Ox (= O3 + NO2), strong solar radiation, and stagnant conditions, suggesting that it was mainly driven by local photochemical formation. We have also investigated the formation and evolution mechanisms of severe haze episodes. Unlike the winter haze events which were mainly caused by intense local emissions coupled with stagnant meteorological conditions, the spring haze events appeared to be influenced by both regional and local factors. For example, there were episodes of long range transport of plumes followed by calm meteorology conditions, which promoted the formation and accumulation of local secondary species, leading to high concentrations of PM. Overall, our results indicate that PM pollutants in urban Korea originate from complex emission sources and atmospheric processes and that the concentrations and composition of PM are controlled by various factors including meteorological conditions, local anthropogenic emissions, and upwind sources. Therefore, understanding the high aerosol pollution followed by efficient strategies to remove precursors are important to control the air pollution.

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