121 results on '"Kramer, Louisa J."'
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2. A Practical Approach for On-Road Measurements of Brake Wear Particles from a Light-Duty Vehicle
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Andersson, Jon, primary, Kramer, Louisa J., additional, Campbell, Michael, additional, Marshall, Ian, additional, Norris, John, additional, Southgate, Jason, additional, de Vries, Simon de, additional, and Waite, Gary, additional
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- 2024
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3. Quantification of within-vehicle exposure to NOx and particles: Variation with outside air quality, route choice and ventilation options
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Matthaios, Vasileios N., Kramer, Louisa J., Crilley, Leigh R., Sommariva, Roberto, Pope, Francis D., and Bloss, William J.
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- 2020
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4. Predicting real-time within-vehicle air pollution exposure with mass-balance and machine learning approaches using on-road and air quality data
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Matthaios, Vasileios N., primary, Knibbs, Luke D., additional, Kramer, Louisa J., additional, Crilley, Leigh R., additional, and Bloss, William J., additional
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- 2023
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5. Investigation of vehicle cold start primary NO2 emissions inferred from ambient monitoring data in the UK and their implications for urban air quality
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Matthaios, Vasileios N., Kramer, Louisa J., Sommariva, Roberto, Pope, Francis D., and Bloss, William J.
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- 2019
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6. Impact of HO2 aerosol uptake on radical levels and O3 production during summertime in Beijing
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Dyson, Joanna E., primary, Whalley, Lisa K., additional, Slater, Eloise J., additional, Woodward-Massey, Robert, additional, Ye, Chunxiang, additional, Lee, James D., additional, Squires, Freya, additional, Hopkins, James R., additional, Dunmore, Rachel E., additional, Shaw, Marvin, additional, Hamilton, Jacqueline F., additional, Lewis, Alastair C., additional, Worrall, Stephen D., additional, Bacak, Asan, additional, Mehra, Archit, additional, Bannan, Thomas J., additional, Coe, Hugh, additional, Percival, Carl J., additional, Ouyang, Bin, additional, Hewitt, C. Nicholas, additional, Jones, Roderic L., additional, Crilley, Leigh R., additional, Kramer, Louisa J., additional, Acton, W. Joe F., additional, Bloss, William J., additional, Saksakulkrai, Supattarachai, additional, Xu, Jingsha, additional, Shi, Zongbo, additional, Harrison, Roy M., additional, Kotthaus, Simone, additional, Grimmond, Sue, additional, Sun, Yele, additional, Xu, Weiqi, additional, Yue, Siyao, additional, Wei, Lianfang, additional, Fu, Pingqing, additional, Wang, Xinming, additional, Arnold, Stephen R., additional, and Heard, Dwayne E., additional
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- 2023
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7. Radical chemistry and ozone production at a UK coastal receptor site.
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Woodward-Massey, Robert, Sommariva, Roberto, Whalley, Lisa K., Cryer, Danny R., Ingham, Trevor, Bloss, William J., Ball, Stephen M., Cox, Sam, Lee, James D., Reed, Chris P., Crilley, Leigh R., Kramer, Louisa J., Bandy, Brian J., Forster, Grant L., Reeves, Claire E., Monks, Paul S., and Heard, Dwayne E.
- Subjects
RADICALS (Chemistry) ,PEROXY radicals ,BUDGET ,MEDIAN (Mathematics) ,METROPOLITAN areas ,OZONE ,SEISMIC anisotropy - Abstract
OH, HO 2 , total and partially speciated RO 2 , and OH reactivity (kOH′) were measured during the July 2015 ICOZA (Integrated Chemistry of OZone in the Atmosphere) project that took place at a coastal site in north Norfolk, UK. Maximum measured daily OH, HO 2 and total RO 2 radical concentrations were in the range 2.6–17 × 10 6 , 0.75–4.2 × 10 8 and 2.3–8.0 × 10 8 molec. cm -3 , respectively. kOH′ ranged from 1.7 to 17.6 s -1 , with a median value of 4.7 s -1. ICOZA data were split by wind direction to assess differences in the radical chemistry between air that had passed over the North Sea (NW–SE sectors) and that over major urban conurbations such as London (SW sector). A box model using the Master Chemical Mechanism (MCMv3.3.1) was in reasonable agreement with the OH measurements, but it overpredicted HO 2 observations in NW–SE air in the afternoon by a factor of ∼ 2–3, although slightly better agreement was found for HO 2 in SW air (factor of ∼ 1.4–2.0 underprediction). The box model severely underpredicted total RO 2 observations in both NW–SE and SW air by factors of ∼ 8–9 on average. Measured radical and kOH′ levels and measurement–model ratios displayed strong dependences on NO mixing ratios, with the results suggesting that peroxy radical chemistry is not well understood under high-NO x conditions. The simultaneous measurement of OH, HO 2 , total RO 2 and kOH′ was used to derive experimental (i.e. observationally determined) budgets for all radical species as well as total RO x (i.e. OH + HO 2 + RO 2). In NW–SE air, the RO x budget could be closed during the daytime within experimental uncertainty, but the rate of OH destruction exceeded the rate of OH production, and the rate of HO 2 production greatly exceeded the rate of HO 2 destruction, while the opposite was true for RO 2. In SW air, the RO x budget analysis indicated missing daytime RO x sources, but the OH budget was balanced, and the same imbalances were found with the HO 2 and RO 2 budgets as in NW–SE air. For HO 2 and RO 2 , the budget imbalances were most severe at high-NO mixing ratios, and the best agreement between HO 2 and RO 2 rates of production and destruction rates was found when the RO 2 + NO rate coefficient was reduced by a factor of 5. A photostationary-steady-state (PSS) calculation underpredicted daytime OH in NW–SE air by ∼ 35 %, whereas agreement (∼ 15 %) was found within instrumental uncertainty (∼ 26 % at 2 σ) in SW air. The rate of in situ ozone production (P (O x)) was calculated from observations of RO x , NO and NO 2 and compared to that calculated from MCM-modelled radical concentrations. The MCM-calculated P (O x) significantly underpredicted the measurement-calculated P (O x) in the morning, and the degree of underprediction was found to scale with NO. [ABSTRACT FROM AUTHOR]
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- 2023
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8. Dynamics of ozone and nitrogen oxides at Summit, Greenland. II. Simulating snowpack chemistry during a spring high ozone event with a 1-D process-scale model
- Author
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Murray, Keenan A., Kramer, Louisa J., Doskey, Paul V., Ganzeveld, Laurens, Seok, Brian, Van Dam, Brie, and Helmig, Detlev
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- 2015
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9. Supplementary material to "Impact of HO2 aerosol uptake on radical levels and O3 production during summertime in Beijing"
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Dyson, Joanna E., primary, Whalley, Lisa K., additional, Slater, Eloise J., additional, Woodward-Massey, Robert, additional, Ye, Chunxiang, additional, Lee, James D., additional, Squires, Freya, additional, Hopkins, James R., additional, Dunmore, Rachel E., additional, Shaw, Marvin, additional, Hamilton, Jacqueline F., additional, Lewis, Alastair C., additional, Worrall, Stephen D., additional, Bacak, Asan, additional, Mehra, Archit, additional, Bannan, Thomas J., additional, Coe, Hugh, additional, Percival, Carl J., additional, Ouyang, Bin, additional, Hewitt, C. Nicholas, additional, Jones, Roderic L., additional, Crilley, Leigh R., additional, Kramer, Louisa J., additional, Acton, W. Joe F., additional, Bloss, William J., additional, Saksakulkrai, Supattarachai, additional, Xu, Jingsha, additional, Shi, Zongbo, additional, Harrison, Roy M., additional, Kotthaus, Simone, additional, Grimmond, Sue, additional, Sun, Yele, additional, Xu, Weiqi, additional, Yue, Siyao, additional, Wei, Lianfang, additional, Fu, Pingqing, additional, Wang, Xinming, additional, Arnold, Stephen R., additional, and Heard, Dwayne E., additional
- Published
- 2022
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10. Impact of HO2 aerosol uptake on radical levels and O3 production during summertime in Beijing
- Author
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Dyson, Joanna E., primary, Whalley, Lisa K., additional, Slater, Eloise J., additional, Woodward-Massey, Robert, additional, Ye, Chunxiang, additional, Lee, James D., additional, Squires, Freya, additional, Hopkins, James R., additional, Dunmore, Rachel E., additional, Shaw, Marvin, additional, Hamilton, Jacqueline F., additional, Lewis, Alastair C., additional, Worrall, Stephen D., additional, Bacak, Asan, additional, Mehra, Archit, additional, Bannan, Thomas J., additional, Coe, Hugh, additional, Percival, Carl J., additional, Ouyang, Bin, additional, Hewitt, C. Nicholas, additional, Jones, Roderic L., additional, Crilley, Leigh R., additional, Kramer, Louisa J., additional, Acton, W. Joe F., additional, Bloss, William J., additional, Saksakulkrai, Supattarachai, additional, Xu, Jingsha, additional, Shi, Zongbo, additional, Harrison, Roy M., additional, Kotthaus, Simone, additional, Grimmond, Sue, additional, Sun, Yele, additional, Xu, Weiqi, additional, Yue, Siyao, additional, Wei, Lianfang, additional, Fu, Pingqing, additional, Wang, Xinming, additional, Arnold, Stephen R., additional, and Heard, Dwayne E., additional
- Published
- 2022
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11. Radical chemistry at a UK coastal receptor site – Part 2: experimental radical budgets and ozone production
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Woodward-Massey, Robert, primary, Sommariva, Roberto, additional, Whalley, Lisa K., additional, Cryer, Danny R., additional, Ingham, Trevor, additional, Bloss, William J., additional, Ball, Stephen M., additional, Lee, James D., additional, Reed, Chris P., additional, Crilley, Leigh R., additional, Kramer, Louisa J., additional, Bandy, Brian J., additional, Forster, Grant L., additional, Reeves, Claire E., additional, Monks, Paul S., additional, and Heard, Dwayne E., additional
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- 2022
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12. Is the ocean surface a source of nitrous acid (HONO) in the marine boundary layer?
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Crilley, Leigh R., primary, Kramer, Louisa J., additional, Pope, Francis D., additional, Reed, Chris, additional, Lee, James D., additional, Carpenter, Lucy J., additional, Hollis, Lloyd D. J., additional, Ball, Stephen M., additional, and Bloss, William J., additional
- Published
- 2021
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13. Evaluating the sensitivity of radical chemistry and ozone formation to ambient VOCs and NOₓ in Beijing
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Whalley, Lisa K., Slater, Eloise J., Woodward-Massey, Robert, Ye, Chunxiang, Lee, James D., Squires, Freya, Hopkins, James R., Dunmore, Rachel E., Shaw, Marvin, Hamilton, Jacqueline F., Lewis, Alastair C., Mehra, Archit, Worrall, Stephen D., Bacak, Asan, Bannan, Thomas J., Coe, Hugh, Percival, Carl J., Ouyang, Bin, Jones, Roderic L., Crilley, Leigh R., Kramer, Louisa J., Bloss, William J., Vu, Tuan, Kotthaus, Simone, Grimmond, Sue, Sun, Yele, Xu, Weiqi, Yue, Siyao, Ren, Lujie, Acton, W. Joe F., Hewitt, C. Nicholas, Wang, Xinming, Fu, Pingqing, and Heard, Dwayne E.
- Abstract
Measurements of OH, HO2, complex RO2 (alkene- and aromatic-related RO2) and total RO2 radicals taken during the integrated Study of AIR Pollution PROcesses in Beijing (AIRPRO) campaign in central Beijing in the summer of 2017, alongside observations of OH reactivity, are presented. The concentrations of radicals were elevated, with OH reaching up to 2.8×107moleculecm−3, HO2 peaking at 1×109moleculecm−3 and the total RO2 concentration reaching 5.5×109moleculecm−3. OH reactivity (k(OH)) peaked at 89 s−1 during the night, with a minimum during the afternoon of ≈22s−1 on average. An experimental budget analysis, in which the rates of production and destruction of the radicals are compared, highlighted that although the sources and sinks of OH were balanced under high NO concentrations, the OH sinks exceeded the known sources (by 15 ppbv h−1) under the very low NO conditions (
- Published
- 2021
14. Evaluating the sensitivity of radical chemistry and ozone formation to ambient VOCs and NOxin Beijing
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Whalley, Lisa K., Slater, Eloise J., Woodward-Massey, Robert, Ye, Chunxiang, Lee, James D., Squires, Freya, Hopkins, James R., Dunmore, Rachel E., Shaw, Marvin, Hamilton, Jacqueline F., Lewis, Alastair C., Mehra, Archit, Worrall, Stephen D., Bacak, Asan, Bannan, Thomas J., Coe, Hugh, Percival, Carl J., Ouyang, Bin, Jones, Roderic L., Crilley, Leigh R., Kramer, Louisa J., Bloss, William J., Vu, Tuan, Kotthaus, Simone, Grimmond, Sue, Sun, Yele, Xu, Weiqi, Yue, Siyao, Ren, Lujie, Joe, W., Nicholas Hewitt, C., Wang, Xinming, Fu, Pingqing, Heard, Dwayne E., Whalley, Lisa K., Slater, Eloise J., Woodward-Massey, Robert, Ye, Chunxiang, Lee, James D., Squires, Freya, Hopkins, James R., Dunmore, Rachel E., Shaw, Marvin, Hamilton, Jacqueline F., Lewis, Alastair C., Mehra, Archit, Worrall, Stephen D., Bacak, Asan, Bannan, Thomas J., Coe, Hugh, Percival, Carl J., Ouyang, Bin, Jones, Roderic L., Crilley, Leigh R., Kramer, Louisa J., Bloss, William J., Vu, Tuan, Kotthaus, Simone, Grimmond, Sue, Sun, Yele, Xu, Weiqi, Yue, Siyao, Ren, Lujie, Joe, W., Nicholas Hewitt, C., Wang, Xinming, Fu, Pingqing, and Heard, Dwayne E.
- Abstract
Measurements of OH, HO2, complex RO2 (alkene-and aromatic-related RO2) and total RO2 radicals taken during the integrated Study of AIR Pollution PROcesses in Beijing (AIRPRO) campaign in central Beijing in the summer of 2017, alongside observations of OH reactivity, are presented. The concentrations of radicals were elevated, with OH reaching up to 2:8 × 107 molecule cm-3, HO2 peaking at 1 × 109 molecule cm-3 and the total RO2 concentration reaching 5:5×109 molecule cm-3. OH reactivity (k.OH/) peaked at 89 s-1 during the night, with a minimum during the afternoon of 22s-1 on average. An experimental budget analysis, in which the rates of production and destruction of the radicals are compared, highlighted that although the sources and sinks of OH were balanced under high NO concentrations, the OH sinks exceeded the known sources (by 15 ppbvh-1) under the very low NO conditions (< 0:5ppbv) experienced in the afternoons, demonstrating a missing OH source consistent with previous studies under high volatile organic compound (VOC) emissions and low NO loadings. Under the highest NO mixing ratios (104 ppbv), the HO2 production rate exceeded the rate of destruction by 50ppbvh-1, whilst the rate of destruction of total RO2 exceeded the production by the same rate, indicating that the net propagation rate of RO2 to HO2 may be substantially slower than assumed. If just 10 % of the RO2 radicals propagate to HO2 upon reaction with NO, the HO2 and RO2 budgets could be closed at high NO, but at low NO this lower RO2 to HO2 propagation rate revealed a missing RO2 sink that was similar in magnitude to the missing OH source. A detailed box model that incorporated the latest Master Chemical Mechanism (MCM3.3.1) reproduced the observed OH concentrations well but over-predicted the observed HO2 under low concentrations of NO (< 1ppbv) and under-predicted RO2 (both the complex RO2 fraction and other RO2 types which we classify as simple RO2) most significantly at the highest NO concent
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- 2021
15. Evaluating the sensitivity of radical chemistry and ozone formation to ambient VOCs and NOx in Beijing
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Whalley, Lisa, Slater, Eloise, Woodward-Massey, Robert, Ye, Chunxiang, Lee, James D., Squires, Freya, Hopkins, James R., Dunmore, Rachel E., Shaw, Marvin, Hamilton, Jacqueline F., Lewis, Alastair C., Mehra, Archit, Worrall, Stephen David, Bacak, Asan, Bannan, Thomas J., Coe, Hugh, Ouyang, Bin, Jones, Roderic L., Crilley, Leigh R., Kramer, Louisa J., Bloss, William J., Vu, Tuan, Kotthaus, Simone, Grimmond, Sue, Sun, Yele, Xu, Weiqi, Yue, Siyao, Ren, Lujie, Acton, W Joe F, Hewitt, C N, Wang, Xinming, Fu, Pingqing, Heard, Dwayne E., Whalley, Lisa, Slater, Eloise, Woodward-Massey, Robert, Ye, Chunxiang, Lee, James D., Squires, Freya, Hopkins, James R., Dunmore, Rachel E., Shaw, Marvin, Hamilton, Jacqueline F., Lewis, Alastair C., Mehra, Archit, Worrall, Stephen David, Bacak, Asan, Bannan, Thomas J., Coe, Hugh, Ouyang, Bin, Jones, Roderic L., Crilley, Leigh R., Kramer, Louisa J., Bloss, William J., Vu, Tuan, Kotthaus, Simone, Grimmond, Sue, Sun, Yele, Xu, Weiqi, Yue, Siyao, Ren, Lujie, Acton, W Joe F, Hewitt, C N, Wang, Xinming, Fu, Pingqing, and Heard, Dwayne E.
- Published
- 2021
16. Interference from alkenes in chemiluminescent NOx measurements
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Alam, Mohammed S., Crilley, Leigh R., Lee, James D., Kramer, Louisa J., Pfrang, Christian, Vázquez-Moreno, Mónica, Ródenas, Milagros, Muñoz, Amalia, and Bloss, William J.
- Abstract
Nitrogen oxides (NOx=NO+NO2) are critical intermediates in atmospheric chemistry and air pollution. NOx levels control the cycling and hence abundance of the primary atmospheric oxidants OH and NO3 and regulate the ozone production which results from the degradation of volatile organic compounds (VOCs) in the presence of sunlight. They are also atmospheric pollutants, and NO2 is commonly included in air quality objectives and regulations. NOx levels also affect the production of the nitrate component of secondary aerosol particles and other pollutants, such as the lachrymator peroxyacetyl nitrate (PAN). The accurate measurement of NO and NO2 is therefore crucial for air quality monitoring and understanding atmospheric composition. The most commonly used approach for the measurement of NO is the chemiluminescent detection of electronically excited NO2 (NO2∗) formed from the NO + O3 reaction within the NOx analyser. Alkenes, ubiquitous in the atmosphere from biogenic and anthropogenic sources, also react with ozone to produce chemiluminescence and thus may contribute to the measured NOx signal. Their ozonolysis reaction may also be sufficiently rapid that their abundance in conventional instrument background cycles, which also utilises the reaction with ozone, differs from that in the measurement cycle such that the background subtraction is incomplete, and an interference effect results. This interference has been noted previously, and indeed, the effect has been used to measure both alkenes and ozone in the atmosphere. Here we report the results of a systematic investigation of the response of a selection of commercial NOx monitors to a series of alkenes. These NOx monitors range from systems used for routine air quality monitoring to atmospheric research instrumentation. The species-investigated range was from short-chain alkenes, such as ethene, to the biogenic monoterpenes. Experiments were performed in the European PHOtoREactor (EUPHORE) to ensure common calibration and samples for the monitors and to unequivocally confirm the alkene levels present (via Fourier transform infrared spectroscopy – FTIR). The instrument interference responses ranged from negligible levels up to 11 %, depending upon the alkene present and conditions used (e.g. the presence of co-reactants and differing humidity). Such interferences may be of substantial importance for the interpretation of ambient NOx data, particularly for high VOC, low NOx environments such as forests or indoor environments where alkene abundance from personal care and cleaning products may be significant.
- Published
- 2020
17. Observations of speciated isoprene nitrates in Beijing: implications for isoprene chemistry
- Author
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Reeves, Claire E., primary, Mills, Graham P., additional, Whalley, Lisa K., additional, Acton, W. Joe F., additional, Bloss, William J., additional, Crilley, Leigh R., additional, Grimmond, Sue, additional, Heard, Dwayne E., additional, Hewitt, C. Nicholas, additional, Hopkins, James R., additional, Kotthaus, Simone, additional, Kramer, Louisa J., additional, Jones, Roderic L., additional, Lee, James D., additional, Liu, Yanhui, additional, Ouyang, Bin, additional, Slater, Eloise, additional, Squires, Freya, additional, Wang, Xinming, additional, Woodward-Massey, Robert, additional, and Ye, Chunxiang, additional
- Published
- 2021
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18. Evaluating the sensitivity of radical chemistry and ozone formation to ambient VOCs and NOx in Beijing
- Author
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Whalley, Lisa, Slater, Eloise, Woodward-Massey, Robert, Ye, Chunxiang, Lee, James D., Squires, Freya, Hopkins, James R., Dunmore, Rachel E., Marvin David Shaw, Hamilton, Jacqueline F., Lewis, Alastair C., Mehra, Archit, Worrall, Stephen David, Bacak, Asan, Bannan, Thomas J., Coe, Hugh, Ouyang, Bin, Jones, Roderic L., Crilley, Leigh R., Kramer, Louisa J., Bloss, William J., Vu, Tuan, Kotthaus, Simone, Grimmond, Sue, Sun, Yele, Xu, Weiqi, Yue, Siyao, Ren, Lujie, Acton, W. Joe F., Hewitt, C. N., Wang, Xinming, Fu, Pingqing, and Heard, Dwayne E.
- Abstract
Measurements of OH, HO2, RO2-complex (alkene and aromatic-related RO2) and total RO2 radicals taken during the AIRPRO campaign in central Beijing in the summer of 2017, alongside observations of OH reactivity are presented. The concentrations of radicals were elevated with OH reaching up to 2.8 × 107 molecule cm−3, HO2 peaked at 1 × 109 molecule cm−3 and the total RO2 concentration reached 5.5 × 109 molecule cm−3. OH reactivity (k(OH)) peaked at 89 s−1 during the night, with a minimum during the afternoons of ~ 22 s−1 on average. An experimental budget analysis, in which the rates of production and destruction of the radicals are compared, highlighted that although the sources and sinks of OH were balanced under high NO concentrations, the OH sinks exceeded the known sources (by 15 ppbv hr−1) under the very low NO conditions (2 production rate exceeded the rate of destruction by ~ 50 ppbv hr−1, whilst the rate of destruction of total-RO2 exceeded the production by the same rate indicating that the net propagation rate of RO2 to HO2 may be substantially slower than assumed. If just 10 % of the RO2 radicals propagate to HO2 upon reaction with NO, the HO2 and RO2 budgets could be closed at high NO, but at low NO this lower RO2 to HO2 propagation rate revealed a missing RO2 sink that was similar in magnitude to the missing OH source. A detailed box model that incorporated the latest MCM chemical mechanism (MCM3.3.1) reproduced the observed OH concentrations well, but over-predicted the observed HO2 under low concentrations of NO (2 (both the complex-RO2 fraction and other RO2 types which we classify as simple-RO2) most significantly at the highest NO concentrations. The model also under-predicted the observed k(OH) consistently by ~ 10 s−1 across all NOx levels highlighting that the good agreement for OH was fortuitous due to a cancellation of missing OH source and sink terms in its budget. Including heterogeneous loss of HO2 to aerosol surfaces did reduce the modelled HO2 concentrations in-line with the observations, but only at NO mixing ratios 2 concentration on several mornings when the Cl atom concentration was calculated to exceed 1 × 104 atoms cm−3 and could reconcile the modelled and measured RO2 concentrations at these times. However, on other mornings, when the Cl atom concentration was lower, large under-predictions in total RO2 remained. Furthermore, the inclusion of Cl atom chemistry did not enhance the modelled RO2 beyond the first few hours after sunrise and so was unable to resolve the modelled under-prediction in RO2 observed at other times of the day. Model scenarios, in which missing VOC reactivity was included as an additional reaction that converted OH to RO2, highlighted that the modelled OH, HO2 and RO2 concentrations were sensitive to the choice of RO2 product. The level of modelled to measured agreement for HO2 and RO2 (both complex and simple) could be improved if the missing OH reactivity formed a larger RO2 species that was able to undergo reaction with NO, followed by isomerisation reactions reforming other RO2 species, before eventually generating HO2. In this work an α-pinene-derived RO2 species was used as an example. In this simulation, consistent with the experimental budget analysis, the model underestimated the observed OH indicating a missing OH source. The model uncertainty, with regards to the types of RO2 species present and the radicals they form upon reaction with NO (HO2 directly or another RO2 species), leads to over an order of magnitude less O3 production calculated from the predicted peroxy radicals than calculated from the observed peroxy radicals at the highest NO concentrations. This demonstrates the rate at which the larger RO2 species propagate to HO2 or to another RO2 or indeed to OH needs to be understood to accurately simulate the rate of ozone production in environments such as Beijing where large multifunctional VOCs are likely present.
- Published
- 2020
19. Elevated levels of OH observed in haze events during wintertime in central Beijing
- Author
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Slater, Eloise, Whalley, Lisa K., Woodward-Massey, Robert, Ye, Chunxiang, Lee, James D., Squires, Freja, Hopkins, James R., Dunmore, Rachel E., Shaw, Marvin, Hamilton, Jacqueline F., Lewis, Alastair C., Crilley, Leigh R., Kramer, Louisa J., Bloss, William J., Vu, Tuan, Sun, Yele, Xu, Weiqi, Yue, Siyao, Ren, Lujie, Acton, W. Joe F., Hewitt, C N, Wang, Xinming, Fu, Pingqing, Heard, Dwayne E., Slater, Eloise, Whalley, Lisa K., Woodward-Massey, Robert, Ye, Chunxiang, Lee, James D., Squires, Freja, Hopkins, James R., Dunmore, Rachel E., Shaw, Marvin, Hamilton, Jacqueline F., Lewis, Alastair C., Crilley, Leigh R., Kramer, Louisa J., Bloss, William J., Vu, Tuan, Sun, Yele, Xu, Weiqi, Yue, Siyao, Ren, Lujie, Acton, W. Joe F., Hewitt, C N, Wang, Xinming, Fu, Pingqing, and Heard, Dwayne E.
- Abstract
Wintertime in situ measurements of OH, HO2 and RO2 radicals and OH reactivity were made in central Beijing during November and December 2016. Exceptionally elevated NO was observed on occasions, up to ∼250 ppbv. The daily maximum mixing ratios for radical species varied significantly day-to-day over the ranges 1–8×106 cm−3 (OH), 0.2–1.5×108 cm−3 (HO2) and 0.3–2.5×108 cm−3 (RO2). Averaged over the full observation period, the mean daytime peak in radicals was 2.7×106, 0.39×108 and 0.88×108 cm−3 for OH, HO2 and total RO2, respectively. The main daytime source of new radicals via initiation processes (primary production) was the photolysis of HONO (∼83 %), and the dominant termination pathways were the reactions of OH with NO and NO2, particularly under polluted haze conditions. The Master Chemical Mechanism (MCM) v3.3.1 operating within a box model was used to simulate the concentrations of OH, HO2 and RO2. The model underpredicted OH, HO2 and RO2, especially when NO mixing ratios were high (above 6 ppbv). The observation-to-model ratio of OH, HO2 and RO2 increased from ∼1 (for all radicals) at 3 ppbv of NO to a factor of ∼3, ∼20 and ∼91 for OH, HO2 and RO2, respectively, at ∼200 ppbv of NO. The significant underprediction of radical concentrations by the MCM suggests a deficiency in the representation of gas-phase chemistry at high NOx. The OH concentrations were surprisingly similar (within 20 % during the day) in and outside of haze events, despite j(O1D) decreasing by 50 % during haze periods. These observations provide strong evidence that gas-phase oxidation by OH can continue to generate secondary pollutants even under high-pollution episodes, despite the reduction in photolysis rates within haze.
- Published
- 2020
20. Radical chemistry at a UK coastal receptor site -- Part 1: observations of OH, HO2, RO2, and OH reactivity and comparison to MCM model predictions.
- Author
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Woodward-Massey, Robert, Sommariva, Roberto, Whalley, Lisa K., Cryer, Danny R., Ingham, Trevor, Bloss, William J., Cox, Sam, Lee, James D., Reed, Chris P., Crilley, Leigh R., Kramer, Louisa J., Bandy, Brian J., Forster, Grant L., Reeves, Claire E., Monks, Paul S., and Heard., Dwayne E.
- Abstract
OH, HO
2 , total and partially-speciated RO2 , and OH reactivity (k'OH) were measured during the July 2015 ICOZA (Integrated Chemistry of OZone in the Atmosphere) project that took place at a coastal site in North Norfolk, UK. Maximum measured daily OH, HO2 , and total RO2 radical concentrations were in the range 2.6-17 × 106, 0.75-4.2 × 108, and 2.3-8.0 × 108 molecule cm-3 , respectively. k'OH ranged from 1.7 to 17.6 s-1 with a median value of 4.7 s-1 . ICOZA data were split by wind direction to assess differences in the radical chemistry between air that had passed over the North Sea (NW-SE sectors) or major urban conurbations such as London (SW sector). A photostationary steady-state (PSS) calculation underpredicted daytime OH in NW-SE air by ~35%, whereas agreement (~15%) was found within instrumental uncertainty (~26% at 2σ) in SW air. A box model using MCMv3.3.1 chemistry was in better agreement with the OH measurements, but it overpredicted HO2 observations in NW-SE air in the afternoon by a factor of ~2-3, although slightly bet ter agreement was found for HO2 in SW air (factor of ~1.4-2.0 underprediction). The box model severely underpredicted total RO2 observations in both NW-SE and SW air by factors of ~8-9 on average. Measured radical and k'OH levels and measurement-to-model ratios displayed strong dependences on NO mixing ratios. The PSS calculation could capture OH observations at high NO but underpredicted the observations at low NO. The box model overpredicted HO2 concentrations at low NO in NW-SE air, whereas in SW air, the measurements and model results were in agreement across the full NO range. The box model underpredicted total RO2 at all NO levels, where the measurement-to-model ratio scaled with NO. This trend has been found in all previous field campaigns in which total RO2 was measured using the ROx LIF technique and suggests that peroxy radical chemistry is not well understood under high NOx conditions. [ABSTRACT FROM AUTHOR]- Published
- 2022
- Full Text
- View/download PDF
21. Radical chemistry at a UK coastal receptor site - Part 2: experimental radical budgets and ozone production.
- Author
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Woodward-Massey, Robert, Sommariva, Roberto, Whalley, Lisa K., Cryer, Danny R., Ingham, Trevor, Bloss, William J., Ball, Stephen M., Lee, James D., Reed, Chris P., Crilley, Leigh R., Kramer, Louisa J., Bandy, Brian J., Forster, Grant L., Reeves, Claire E., Monks, Paul S., and Heard, Dwayne E.
- Abstract
In our companion paper (Woodward-Massey et al., 2022), we presented measurements of radical species and OH reactivity (k'OH) made in summer 2015 during the ICOZA (Integrated Chemistry of OZone in the Atmosphere) field campaign at the Weybourne Atmospheric Observatory, a site on the east coast of the UK. In the present work, we used the simultaneous measurement of OH, HO
2 , total RO2 , and k'OH to derive experimental (i.e., observationally determined) budgets for all radical species as well as total ROx (= OH + HO2 + RO2 ). Data were separated according to wind direction: prevailing SW winds (with influence from London and other major conurbations), and all other winds (NW-SE; predominantly marine in origin). In NW-SE air, the ROx budget could be closed during the daytime within experimental uncertainty but OH destruction exceeded OH production, and HO2 production greatly exceeded HO2 destruction while the opposite was true for RO2 . In SW air, the ROx budget analysis indicated missing daytime ROx sources but the OH budget was balanced, and the same imbalances were found with the HO2 and RO2 budgets as in NW-SE air. For HO2 and RO2 , the budget imbalances were most severe at high NO mixing ratios. We explored several mechanistic modifications to the experimental budgets to try to reconcile the HO2 and RO2 budget imbalances: (1) the addition of generic radical recycling processes, (2) reduction of the rate of RO2 x HO2 conversion, (3) inclusion of heterogeneous HO2 uptake, and (4) addition of chlorine chemistry. The best agreement between HO2 and RO2 production and destruction rates was found for option (2), in which we reduced the RO2 + NO rate constant by a factor of 5. The rate of in situ ozone production (P(Ox )) was calculated from observations of ROx , NO, and NO2 and compared to that calculated from MCM-modelled radical concentrations. The MCM-calculated P(Ox ) significantly 35 underpredicted the measurement-calculated P(Ox ) in the morning, and the degree of underprediction was found to scale with NO. [ABSTRACT FROM AUTHOR]- Published
- 2022
- Full Text
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22. Evaluating the sensitivity of radical chemistry and ozone formation to ambient VOCs and NOx in Beijing
- Author
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Whalley, Lisa K., primary, Slater, Eloise J., additional, Woodward-Massey, Robert, additional, Ye, Chunxiang, additional, Lee, James D., additional, Squires, Freya, additional, Hopkins, James R., additional, Dunmore, Rachel E., additional, Shaw, Marvin, additional, Hamilton, Jacqueline F., additional, Lewis, Alastair C., additional, Mehra, Archit, additional, Worrall, Stephen D., additional, Bacak, Asan, additional, Bannan, Thomas J., additional, Coe, Hugh, additional, Ouyang, Bin, additional, Jones, Roderic L., additional, Crilley, Leigh R., additional, Kramer, Louisa J., additional, Bloss, William J., additional, Vu, Tuan, additional, Kotthaus, Simone, additional, Grimmond, Sue, additional, Sun, Yele, additional, Xu, Weiqi, additional, Yue, Siyao, additional, Ren, Lujie, additional, Acton, W. Joe F., additional, Hewitt, C. Nicholas, additional, Wang, Xinming, additional, Fu, Pingqing, additional, and Heard, Dwayne E., additional
- Published
- 2020
- Full Text
- View/download PDF
23. Supplementary material to "Interference from alkenes in chemiluminescent NOx measurements"
- Author
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Alam, Mohammed S., primary, Crilley, Leigh R., additional, Lee, James D., additional, Kramer, Louisa J., additional, Pfrang, Christian, additional, Vázquez-Moreno, Mónica, additional, Muñoz, Amalia, additional, Ródenas, Milagros, additional, and Bloss, William J., additional
- Published
- 2020
- Full Text
- View/download PDF
24. Interference from alkenes in chemiluminescent NOx measurements
- Author
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Alam, Mohammed S., primary, Crilley, Leigh R., additional, Lee, James D., additional, Kramer, Louisa J., additional, Pfrang, Christian, additional, Vázquez-Moreno, Mónica, additional, Muñoz, Amalia, additional, Ródenas, Milagros, additional, and Bloss, William J., additional
- Published
- 2020
- Full Text
- View/download PDF
25. Nitrous acid (HONO) emissions under real-world driving conditions from vehicles in a UK road tunnel
- Author
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Kramer, Louisa J., primary, Crilley, Leigh R., additional, Adams, Thomas J., additional, Ball, Stephen M., additional, Pope, Francis D., additional, and Bloss, William J., additional
- Published
- 2020
- Full Text
- View/download PDF
26. An instrument for in situ measurement of total ozone reactivity
- Author
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Sommariva, Roberto, primary, Kramer, Louisa J., additional, Crilley, Leigh R., additional, Alam, Mohammed S., additional, and Bloss, William J., additional
- Published
- 2020
- Full Text
- View/download PDF
27. Effect of aerosol composition on the performance of low-cost optical particle counter correction factors
- Author
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Crilley, Leigh R., primary, Singh, Ajit, additional, Kramer, Louisa J., additional, Shaw, Marvin D., additional, Alam, Mohammed S., additional, Apte, Joshua S., additional, Bloss, William J., additional, Hildebrandt Ruiz, Lea, additional, Fu, Pingqing, additional, Fu, Weiqi, additional, Gani, Shahzad, additional, Gatari, Michael, additional, Ilyinskaya, Evgenia, additional, Lewis, Alastair C., additional, Ng'ang'a, David, additional, Sun, Yele, additional, Whitty, Rachel C. W., additional, Yue, Siyao, additional, Young, Stuart, additional, and Pope, Francis D., additional
- Published
- 2020
- Full Text
- View/download PDF
28. Supplementary material to "Observations of speciated isoprene nitrates in Beijing: implications for isoprene chemistry"
- Author
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Reeves, Claire E., primary, Mills, Graham P., additional, Whalley, Lisa K., additional, Acton, W. Joe F., additional, Bloss, William J., additional, Crilley, Leigh R., additional, Grimmond, Sue, additional, Heard, Dwayne E., additional, Hewitt, C. Nicholas, additional, Hopkins, James R., additional, Kotthaus, Simone, additional, Kramer, Louisa J., additional, Jones, Roderic L., additional, Lee, James D., additional, Liu, Yanhui, additional, Ouyang, Bin, additional, Slater, Eloise, additional, Squires, Freya, additional, Wang, Xinming, additional, Woodward-Massey, Robert, additional, and Ye, Chunxiang, additional
- Published
- 2020
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- View/download PDF
29. Observations of speciated isoprene nitrates in Beijing: implications for isoprene chemistry
- Author
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Reeves, Claire E., primary, Mills, Graham P., additional, Whalley, Lisa K., additional, Acton, W. Joe F., additional, Bloss, William J., additional, Crilley, Leigh R., additional, Grimmond, Sue, additional, Heard, Dwayne E., additional, Hewitt, C. Nicholas, additional, Hopkins, James R., additional, Kotthaus, Simone, additional, Kramer, Louisa J., additional, Jones, Roderic L., additional, Lee, James D., additional, Liu, Yanhui, additional, Ouyang, Bin, additional, Slater, Eloise, additional, Squires, Freya, additional, Wang, Xinming, additional, Woodward-Massey, Robert, additional, and Ye, Chunxiang, additional
- Published
- 2020
- Full Text
- View/download PDF
30. Intercomparison of nitrous acid (HONO) measurement techniques in a megacity (Beijing)
- Author
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Crilley, Leigh R., primary, Kramer, Louisa J., additional, Ouyang, Bin, additional, Duan, Jun, additional, Zhang, Wenqian, additional, Tong, Shengrui, additional, Ge, Maofa, additional, Tang, Ke, additional, Qin, Min, additional, Xie, Pinhua, additional, Shaw, Marvin D., additional, Lewis, Alastair C., additional, Mehra, Archit, additional, Bannan, Thomas J., additional, Worrall, Stephen D., additional, Priestley, Michael, additional, Bacak, Asan, additional, Coe, Hugh, additional, Allan, James, additional, Percival, Carl J., additional, Popoola, Olalekan A. M., additional, Jones, Roderic L., additional, and Bloss, William J., additional
- Published
- 2019
- Full Text
- View/download PDF
31. Nitrous acid (HONO) emissions under real-world driving conditions from vehicles in a UK road tunnel
- Author
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Kramer, Louisa J., primary, Crilley, Leigh R., additional, Adams, Thomas J., additional, Ball, Stephen M., additional, Pope, Francis D., additional, and Bloss, William J., additional
- Published
- 2019
- Full Text
- View/download PDF
32. Supplementary material to "Nitrous acid (HONO) emissions under real-world driving conditions from vehicles in a UK road tunnel"
- Author
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Kramer, Louisa J., primary, Crilley, Leigh R., additional, Adams, Thomas J., additional, Ball, Stephen M., additional, Pope, Francis D., additional, and Bloss, William J., additional
- Published
- 2019
- Full Text
- View/download PDF
33. Validity and limitations of simple reaction kinetics to calculate concentrations of organic compounds from ion counts in PTR-MS
- Author
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Holzinger, Rupert, primary, Acton, W. Joe F., additional, Bloss, William J., additional, Breitenlechner, Martin, additional, Crilley, Leigh R., additional, Dusanter, Sébastien, additional, Gonin, Marc, additional, Gros, Valerie, additional, Keutsch, Frank N., additional, Kiendler-Scharr, Astrid, additional, Kramer, Louisa J., additional, Krechmer, Jordan E., additional, Languille, Baptiste, additional, Locoge, Nadine, additional, Lopez-Hilfiker, Felipe, additional, Materić, Dušan, additional, Moreno, Sergi, additional, Nemitz, Eiko, additional, Quéléver, Lauriane L. J., additional, Sarda Esteve, Roland, additional, Sauvage, Stéphane, additional, Schallhart, Simon, additional, Sommariva, Roberto, additional, Tillmann, Ralf, additional, Wedel, Sergej, additional, Worton, David R., additional, Xu, Kangming, additional, and Zaytsev, Alexander, additional
- Published
- 2019
- Full Text
- View/download PDF
34. Surface–atmosphere exchange of inorganic water-soluble gases and associated ions in bulk aerosol above agricultural grassland pre- and postfertilisation
- Author
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Ramsay, Robbie, Marco, Chiara F., Heal, Mathew R., Twigg, Marsailidh M., Cowan, Nicholas, Jones, Matthew R., Leeson, Sarah R., Bloss, William J., Kramer, Louisa J., Crilley, Leigh, Sörgel, Matthias, Andreae, Meinrat, and Nemitz, Eiko
- Subjects
Agriculture and Soil Science ,Atmospheric Sciences - Abstract
The increasing use of intensive agricultural practices can lead to damaging consequences for the atmosphere through enhanced emissions of air pollutants. However, there are few direct measurements of the surface–atmosphere exchange of trace gases and water-soluble aerosols over agricultural grassland, particularly of reactive nitrogen compounds. In this study, we present measurements of the concentrations, fluxes and deposition velocities of the trace gases HCl, HONO, HNO3, SO2 and NH3 as well as their associated water-soluble aerosol counterparts Cl−, NO2-, NO3-, SO42- and NH4+ as determined hourly for 1 month in May–June 2016 over agricultural grassland near Edinburgh, UK, pre- and postfertilisation. Measurements were made using the Gradient of Aerosols and Gases Online Registrator (GRAEGOR) wet-chemistry two-point gradient instrument. Emissions of NH3 peaked at 1460 ngm-2s-1 3 h after fertilisation, with an emission of HONO peaking at 4.92 ngm-2s-1 occurring 5 h after fertilisation. Apparent emissions of NO3- aerosol were observed after fertilisation which, coupled with a divergence of HNO3 deposition velocity (Vd) from its theoretical maximum value, suggested the reaction of emitted NH3 with atmospheric HNO3 to form ammonium nitrate aerosol. The use of the conservative exchange fluxes of tot-NH4+ and tot-NO3- indicated net emission of tot-NO3-, implying a ground source of HNO3 after fertilisation. Daytime concentrations of HONO remained above the detection limit (30 ng m−3) throughout the campaign, suggesting a daytime source for HONO at the site. Whilst the mean Vd of NH4+ was 0.93 mm s−1 in the range expected for the accumulation mode, the larger average Vd for Cl− (3.65 mm s−1), NO3- (1.97 mm s−1) and SO42- (1.89 mm s−1) reflected the contribution of a super-micron fraction and decreased with increasing PM2.5∕PM10 ratio (a proxy measurement for aerosol size), providing evidence – although limited by the use of a proxy for aerosol size – of a size dependence of aerosol deposition velocity for aerosol chemical compounds, which has been suggested from process-orientated models of aerosol deposition.
- Published
- 2018
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35. Intercomparison of nitrous acid (HONO) measurement techniques in a megacity (Beijing)
- Author
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Crilley, Leigh R., Kramer, Louisa J., Ouyang, Bin, Duan, Jun, Zhang, Wenqian, Tong, Shengrui, Ge, Maofa, Tang, Ke, Qin, Min, Xie, Pinhua, Shaw, Marvin D., Lewis, Alastair C., Mehra, Archit, Bannan, Thomas J., Worrall, Stephen D., Priestley, Michael, Bacak, Asan, Coe, Hugh, Allan, James, Percival, Carl J., Popoola, Olalekan A.M., Jones, Roderic L., Bloss, William J., Crilley, Leigh R., Kramer, Louisa J., Ouyang, Bin, Duan, Jun, Zhang, Wenqian, Tong, Shengrui, Ge, Maofa, Tang, Ke, Qin, Min, Xie, Pinhua, Shaw, Marvin D., Lewis, Alastair C., Mehra, Archit, Bannan, Thomas J., Worrall, Stephen D., Priestley, Michael, Bacak, Asan, Coe, Hugh, Allan, James, Percival, Carl J., Popoola, Olalekan A.M., Jones, Roderic L., and Bloss, William J.
- Abstract
Nitrous acid (HONO) is a key determinant of the daytime radical budget in the daytime boundary layer, with quantitative measurement required to understand OH radical abundance. Accurate and precise measurements of HONO are therefore needed; however HONO is a challenging compound to measure in the field, in particular in a chemically complex and highly polluted environment. Here we report an intercomparison exercise between HONO measurements performed by two wet chemical techniques (the commercially available a long-path absorption photometer (LOPAP) and a custom-built instrument) and two broadband cavity-enhanced absorption spectrophotometer (BBCEAS) instruments at an urban location in Beijing. In addition, we report a comparison of HONO measurements performed by a time-of-flight chemical ionization mass spectrometer (ToF-CIMS) and a selected ion flow tube mass spectrometer (SIFT-MS) to the more established techniques (wet chemical and BBCEAS). The key finding from the current work was that all instruments agree on the temporal trends and variability in HONO (r2 > 0.97), yet they displayed some divergence in absolute concentrations, with the wet chemical methods consistently higher overall than the BBCEAS systems by between 12 % and 39 %. We found no evidence for any systematic bias in any of the instruments, with the exception of measurements near instrument detection limits. The causes of the divergence in absolute HONO concentrations were unclear, and may in part have been due to spatial variability, i.e. differences in instrument location and/or inlet position, but this observation may have been more associative than casual.
- Published
- 2019
36. Validity and limitations of simple reaction kinetics to calculate concentrations of organic compounds from ion counts in PTR-MS
- Author
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Sub Atmospheric physics and chemistry, Marine and Atmospheric Research, Holzinger, Rupert, Acton, W. Joe F., Bloss, William J., Breitenlechner, Martin, Crilley, Leigh R., Dusanter, Sebastien, Gonin, Marc, Gros, Valerie, Keutsch, Frank N., Kiendler-Scharr, Astrid, Kramer, Louisa J., Krechmer, Jordan E., Languille, Baptiste, Locoge, Nadine, Lopez-Hilfiker, Felipe, Materic, Dusan, Moreno, Sergi, Nemitz, Eiko, Quelever, Lauriane L. J., Esteve, Roland Sarda, Sauvage, Stephane, Schallhart, Simon, Sommariva, Roberto, Tillmann, Ralf, Wedel, Sergej, Worton, David R., Xu, Kangming, Zaytsev, Alexander, Sub Atmospheric physics and chemistry, Marine and Atmospheric Research, Holzinger, Rupert, Acton, W. Joe F., Bloss, William J., Breitenlechner, Martin, Crilley, Leigh R., Dusanter, Sebastien, Gonin, Marc, Gros, Valerie, Keutsch, Frank N., Kiendler-Scharr, Astrid, Kramer, Louisa J., Krechmer, Jordan E., Languille, Baptiste, Locoge, Nadine, Lopez-Hilfiker, Felipe, Materic, Dusan, Moreno, Sergi, Nemitz, Eiko, Quelever, Lauriane L. J., Esteve, Roland Sarda, Sauvage, Stephane, Schallhart, Simon, Sommariva, Roberto, Tillmann, Ralf, Wedel, Sergej, Worton, David R., Xu, Kangming, and Zaytsev, Alexander
- Published
- 2019
37. Validity and limitations of simple reaction kinetics to calculate concentrations of organic compounds from ion counts in PTR-MS
- Author
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Holzinger, Rupert, Acton, W. Joe F., Bloss, William J., Breitenlechner, Martin, Crilley, Leigh R., Dusanter, Sébastien, Gonin, Marc, Gros, Valerie, Keutsch, Frank N., Kiendler-Scharr, Astrid, Kramer, Louisa J., Krechmer, Jordan E., Languille, Baptiste, Locoge, Nadine, Lopez-Hilfiker, Felipe, Materić, Dušan, Moreno, Sergi, Nemitz, Eiko, Quéléver, Lauriane L.J., Sarda Esteve, Roland, Sauvage, Stéphane, Schallhart, Simon, Sommariva, Roberto, Tillmann, Ralf, Wedel, Sergej, Worton, David R., Xu, Kangming, Zaytsev, Alexander, Holzinger, Rupert, Acton, W. Joe F., Bloss, William J., Breitenlechner, Martin, Crilley, Leigh R., Dusanter, Sébastien, Gonin, Marc, Gros, Valerie, Keutsch, Frank N., Kiendler-Scharr, Astrid, Kramer, Louisa J., Krechmer, Jordan E., Languille, Baptiste, Locoge, Nadine, Lopez-Hilfiker, Felipe, Materić, Dušan, Moreno, Sergi, Nemitz, Eiko, Quéléver, Lauriane L.J., Sarda Esteve, Roland, Sauvage, Stéphane, Schallhart, Simon, Sommariva, Roberto, Tillmann, Ralf, Wedel, Sergej, Worton, David R., Xu, Kangming, and Zaytsev, Alexander
- Abstract
In September 2017, we conducted a proton-transfer-reaction mass-spectrometry (PTR-MS) intercomparison campaign at the CESAR observatory, a rural site in the central Netherlands near the village of Cabauw. Nine research groups deployed a total of 11 instruments covering a wide range of instrument types and performance. We applied a new calibration method based on fast injection of a gas standard through a sample loop. This approach allows calibrations on timescales of seconds, and within a few minutes an automated sequence can be run allowing one to retrieve diagnostic parameters that indicate the performance status. We developed a method to retrieve the mass-dependent transmission from the fast calibrations, which is an essential characteristic of PTR-MS instruments, limiting the potential to calculate concentrations based on counting statistics and simple reaction kinetics in the reactor/drift tube. Our measurements show that PTR-MS instruments follow the simple reaction kinetics if operated in the standard range for pressures and temperature of the reaction chamber (i.e. 1–4 mbar, 30–120∘, respectively), as well as a reduced field strength E∕N in the range of 100–160 Td. If artefacts can be ruled out, it becomes possible to quantify the signals of uncalibrated organics with accuracies better than ±30 %. The simple reaction kinetics approach produces less accurate results at E∕N levels below 100 Td, because significant fractions of primary ions form water hydronium clusters. Deprotonation through reactive collisions of protonated organics with water molecules needs to be considered when the collision energy is a substantial fraction of the exoergicity of the proton transfer reaction and/or if protonated organics undergo many collisions with water molecules.
- Published
- 2019
38. Supplementary material to "Effect of aerosol composition on the performance of low-cost optical particle counter correction factors"
- Author
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Crilley, Leigh R., primary, Singh, Ajit, additional, Kramer, Louisa J., additional, Shaw, Marvin D., additional, Alam, Mohammed S., additional, Apte, Joshua S., additional, Bloss, William J., additional, Hildebrandt Ruiz, Lea, additional, Fu, Pingqing, additional, Fu, Weiqi, additional, Gani, Shahzad, additional, Gatari, Michael, additional, Ilyinskaya, Evgenia, additional, Lewis, Alastair C., additional, Ng'ang'a, David, additional, Sun, Yele, additional, Whitty, Rachel C. W., additional, Yue, Siyao, additional, Young, Stuart, additional, and Pope, Francis D., additional
- Published
- 2019
- Full Text
- View/download PDF
39. Effect of aerosol composition on the performance of low-cost optical particle counter correction factors
- Author
-
Crilley, Leigh R., primary, Singh, Ajit, additional, Kramer, Louisa J., additional, Shaw, Marvin D., additional, Alam, Mohammed S., additional, Apte, Joshua S., additional, Bloss, William J., additional, Hildebrandt Ruiz, Lea, additional, Fu, Pingqing, additional, Fu, Weiqi, additional, Gani, Shahzad, additional, Gatari, Michael, additional, Ilyinskaya, Evgenia, additional, Lewis, Alastair C., additional, Ng'ang'a, David, additional, Sun, Yele, additional, Whitty, Rachel C. W., additional, Yue, Siyao, additional, Young, Stuart, additional, and Pope, Francis D., additional
- Published
- 2019
- Full Text
- View/download PDF
40. An instrument for in-situ measurement of total ozone reactivity
- Author
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Sommariva, Roberto, primary, Kramer, Louisa J., additional, Crilley, Leigh R., additional, Alam, Mohammed S., additional, and Bloss, William J., additional
- Published
- 2019
- Full Text
- View/download PDF
41. Supplementary material to "Intercomparison of nitrous acid (HONO) measurement techniques in a megacity (Beijing)"
- Author
-
Crilley, Leigh R., primary, Kramer, Louisa J., additional, Ouyang, Bin, additional, Duan, Jun, additional, Zhang, Wenqian, additional, Tong, Shengrui, additional, Ge, Maofa, additional, Tang, Ke, additional, Qin, Min, additional, Xe, Pinhua, additional, Shaw, Marvin D., additional, Lewis, Alastair C., additional, Mehra, Archit, additional, Bannan, Thomas J., additional, Worrall, Stephen D., additional, Priestley, Michael, additional, Bacak, Asan, additional, Coe, Hugh, additional, Allan, James, additional, Percival, Carl J., additional, Popoola, Olalekan A. M., additional, Jones, Roderic L., additional, and Bloss, William J., additional
- Published
- 2019
- Full Text
- View/download PDF
42. Supplementary material to "Validity and limitations of simple reaction kinetics to calculate concentrations of organic compounds from ion counts in PTR-MS"
- Author
-
Holzinger, Rupert, primary, Acton, W. Joe F., additional, Bloss, William J., additional, Breitenlechner, Martin, additional, Crilley, Leigh R., additional, Dusanter, Sébastien, additional, Gonin, Marc, additional, Gros, Valerie, additional, Keutsch, Frank N., additional, Kiendler-Scharr, Astrid, additional, Kramer, Louisa J., additional, Krechmer, Jordan E., additional, Languille, Baptiste, additional, Locoge, Nadine, additional, Lopez-Hilfiker, Felipe, additional, Materić, Dušan, additional, Moreno, Sergi, additional, Nemitz, Eiko, additional, Quéléver, Lauriane L. J., additional, Sarda Esteve, Roland, additional, Sauvage, Stéphane, additional, Schallhart, Simon, additional, Sommariva, Roberto, additional, Tillmann, Ralf, additional, Wedel, Sergej, additional, Worton, David R., additional, Xu, Kangming, additional, and Zaytsev, Alexander, additional
- Published
- 2019
- Full Text
- View/download PDF
43. Surface–atmosphere exchange of inorganic water-soluble gases and associated ions in bulk aerosol above agricultural grassland pre- and postfertilisation
- Author
-
Ramsay, Robbie, primary, Di Marco, Chiara F., additional, Heal, Mathew R., additional, Twigg, Marsailidh M., additional, Cowan, Nicholas, additional, Jones, Matthew R., additional, Leeson, Sarah R., additional, Bloss, William J., additional, Kramer, Louisa J., additional, Crilley, Leigh, additional, Sörgel, Matthias, additional, Andreae, Meinrat, additional, and Nemitz, Eiko, additional
- Published
- 2018
- Full Text
- View/download PDF
44. Evaluating the sensitivity of radical chemistry and ozone formation to 1ambient VOCs and NOx in Beijing.
- Author
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Whalley, Lisa K., Slater, Eloise J., Woodward-Massey, Robert, Chunxiang Ye, Lee, James D., Squires, Freya, Hopkins, James R., Dunmore, Rachel E., Shaw, Marvin, Hamilton, Jacqueline F., Lewis, Alastair C., Mehra, Archit, Worrall, Stephen D., Bacak, Asan, Bannan, Thomas J., Coe, Hugh, Ouyang, Bin, Jones, Roderic L., Crilley, Leigh R., and Kramer, Louisa J.
- Abstract
Measurements of OH, HO
2 , RO2 -complex (alkene and aromatic-related RO2 ) and total RO2 radicals taken during the AIRPRO campaign in central Beijing in the summer of 2017, alongside observations of OH reactivity are presented. The concentrations of radicals were elevated with OH reaching up to 2.8 x 107 molecule cm-3 , HO2 peaked at 1 x 109 molecule cm-3 and the total RO2 concentration reached 5.5 x 109 molecule cm-3 . OH reactivity (k(OH)) peaked at 89 s-1 during the night, with a minimum during the afternoons of ~22 s-1 on average. An experimental budget analysis, in which the rates of production and destruction of the radicals are compared, highlighted that although the sources and sinks of OH were balanced under high NO concentrations, the OH sinks exceeded the known sources (by 15 ppbv hr-1 ) under the very low NO conditions (<0.5 ppbv) experienced in the afternoons, demonstrating a missing OH source consistent with previous studies under high volatile organic compound (VOC), low NO loadings. Under the highest NO mixing ratios (104 ppbv), the HO2 production rate exceeded the rate of destruction by ~ 50 ppbv hr-1 , whilst the rate of destruction of total-RO2 exceeded the production by the same rate indicating that the net propagation rate of RO2 to HO2 may be substantially slower than assumed. If just 10% of the RO2 radicals propagate to HO2 upon reaction with NO, the HO2 and RO2 budgets could be closed at high NO, but at low NO this lower RO2 to HO2 propagation rate revealed a missing RO2 sink that was similar in magnitude to the missing OH source. A detailed box model that incorporated the latest MCM chemical mechanism (MCM3.3.1) reproduced the observed OH concentrations well, but over-predicted the observed HO2 under low concentrations of NO (<1 ppbv) and under-predicted RO2 (both the complex-RO2 fraction and other RO2 types which we classify as simple-RO2 ) most significantly at the highest NO concentrations. The model also under-predicted the observed k(OH) consistently by ~10 s-1 across all NO[sub x] levels highlighting that the good agreement for OH was fortuitous due to a cancellation of missing OH source and sink terms in its budget. Including heterogeneous loss of HO2 to aerosol surfaces did reduce the modelled HO2 concentrations in-line with the observations, but only at NO mixing ratios <0.3 ppbv. The inclusion of Cl atoms, formed from the photolysis of nitryl chloride, enhanced the modelled RO2 concentration on several mornings when the Cl atom concentration was calculated to exceed 1 x 104 atoms cm-3 and could reconcile the modelled and measured RO2 concentrations at these times. However, on other mornings, when the Cl atom concentration was lower, large under-predictions in total RO2 remained. Furthermore, the inclusion of Cl atom chemistry did not enhance the modelled RO2 beyond the first few hours after sunrise and so was unable to resolve the modelled under-prediction in RO2 observed at other times of the day. Model scenarios, in which missing VOC reactivity was included as an additional reaction that converted OH to RO2 , highlighted that the modelled OH, HO2 and RO2 concentrations were sensitive to the choice of RO2 product. The level of modelled to measured agreement for HO2 and RO2 (both complex and simple) could be improved if the missing OH reactivity formed a larger RO2 species that was able to undergo reaction with NO, followed by isomerisation reactions reforming other RO2 species, before eventually generating HO2 . In this work an α-pinene-derived RO2 species was used as an example. In this simulation, consistent with the experimental budget analysis, the model underestimated the observed OH indicating a missing OH source. The model uncertainty, with regards to the types of RO2 species present and the radicals they form upon reaction with NO (HO2 directly or another RO2 species), leads to over an order of magnitude less O3 production calculated from the predicted peroxy radicals than calculated from the observed peroxy radicals at the highest NO concentrations. This demonstrates the rate at which the larger RO2 species propagate to HO2 or to another RO2 or indeed to OH needs to be understood to accurately simulate the rate of ozone production in environments such as Beijing where large multifunctional VOCs are likely present. [ABSTRACT FROM AUTHOR]- Published
- 2020
- Full Text
- View/download PDF
45. Interference from alkenes in chemiluminescent NOx measurements.
- Author
-
Alam, Mohammed S., Crilley, Leigh R., Lee, James D., Kramer, Louisa J., Pfrang, Christian, Vázquez-Moreno, Mónica, Muñoz, Amalia, Ródenas, Milagros, and Bloss, William J.
- Subjects
AIR quality monitoring ,OZONIZATION ,PEROXYACETYL nitrate ,INTERMEDIATES (Chemistry) ,VOLATILE organic compounds ,HYGIENE products ,AIR pollutants - Abstract
Nitrogen oxides (NO
x = NO + NO2 ) are critical intermediates in atmospheric chemistry. NOx levels control the cycling and hence abundance of the primary atmospheric oxidants OH and NO3 , and regulate the ozone production which results from the degradation of volatile organic compounds (VOCs) in the presence of sunlight. They are also atmospheric pollutants, and NO2 is commonly included in air quality objectives and regulations. NOx levels also affect the production of the nitrate component of secondary aerosol particles and other pollutants such as the lachrymator peroxyacetyl nitrate (PAN). The accurate measurement of NO and NO2 is therefore crucial to air quality monitoring and understanding atmospheric composition. The most commonly used approach for measurement of NO is chemiluminescent detection of electronically excited NO2 (NO2 *) from the NO + O3 reaction. Alkenes, ubiquitous in the atmosphere from biogenic and anthropogenic sources, also react with ozone to produce chemiluminescence and thus may contribute to the measured NOx signal. Their ozonolysis reaction may also be sufficiently rapid that their abundance in the instrument background cycle, which also utilises reaction with ozone, differs from the measurement cycle - such that the background subtraction is incomplete, and an interference effect results. This interference has been noted previously, and indeed the effect has been used to measure both alkenes and ozone in the atmosphere. Here we report the results of a systematic investigation of the response of a selection of commercial NOx monitors, ranging from systems used for routine air quality monitoring to atmospheric research instrumentation, to a series of alkenes. Alkenes investigated range from short chain alkenes, such as ethene, to the biogenic monoterpenes. Experiments were performed in the European Photoreactor (EUPHORE) to ensure common calibration and samples for the monitors, and to unequivocally confirm the alkene levels present (via FTIR). The instrument interference responses ranged from negligible levels up to 11% depending upon the alkene present and conditions used (e.g. presence of co-reactants and differing humidity). Such interferences may be of substantial importance for the interpretation of ambient NOx data, particularly for high-VOC, low-NOx environments such as forests, or indoor environments where alkene abundance from personal care and cleaning products may be significant. [ABSTRACT FROM AUTHOR]- Published
- 2020
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46. Observations of speciated isoprene nitrates in Beijing: implications for isoprene chemistry.
- Author
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Reeves, Claire E., Mills, Graham P., Whalley, Lisa K., Acton, W. Joe F., Bloss, William J., Crilley, Leigh R., Grimmond, Sue, Heard, Dwayne E., Hewitt, C. Nicholas, Hopkins, James R., Kotthaus, Simone, Kramer, Louisa J., Jones, Roderic L., Lee, James D., Yanhui Liu, Bin Ouyang, Slater, Eloise, Squires, Freya, Xinming Wang, and Woodward-Massey, Robert
- Abstract
Isoprene is the most important biogenic volatile organic compound in the atmosphere. Its calculated impact on ozone (O
3 ) is critically dependent on the model isoprene oxidation chemical scheme, in particular the way the isoprene-derived nitrates (IN) are treated. By combining gas chromatography with mass spectrometry, we have developed a system capable of separating, and unambiguously measuring, individual IN isomers. In this paper we report measurements from its first field deployment, which took place in Beijing as part of the Atmospheric Pollution and Human Health in a Chinese Megacity (APHH-Beijing) programme, along with box model simulations using the Master Chemical Mechanism (MCM) (v.3.3.1) to assess the key processes affecting the production and loss of the IN. Seven individual isoprene nitrates were identified and quantified during the summer campaign: two β-isoprene hydroxy nitrates (IHN); four δ isoprene carbonyl nitrates (ICN); and propanone nitrate. Whilst we had previously demonstrated that the system can measure the four δ-IHN, we found no evidence of them in Beijing. The two β-IHN mixing ratios are well correlated with an R² value of 0.85. The mean for their ratio ((1-OH, 2-ONO2 )-IHN : (4-OH, 3-ONO2 )-IHN) is 3.4 and exhibits no clear diel cycle (the numbers in the names indicate the carbon (C) atom in the isoprene chain to which the radical is added). Examining this in a box model demonstrates its sensitivity to nitric oxide (NO), with lower NO mixing ratios favouring (1-OH, 2-ONO2 )-IHN over (4-OH, 3-ONO2 )-IHN. This is largely a reflection of the modelled ratios of their respective precursor peroxy radicals which, at NO mixing ratios of less than 1 part per billion (ppb), increase substantially with decreasing NO. Interestingly, this ratio in the peroxy radicals still exceeds the kinetic ratio (i.e. their initial ratio based on the yields of the adducts from OH addition to isoprene and the rates of reaction of the adducts with oxygen (O2 )) even at NO mixing ratios as high as 100 ppb. The relationship of the observed β-IHN ratio with NO is much weaker than modelled, partly due to far fewer data points, but it agrees with the model simulation in so far as there tend to be larger ratios at sub 1 ppb amounts of NO. Of the δ-ICN, the two trans (E) isomers are observed to have the highest mixing ratios and the mean isomer ratio (E-(4-ONO2 , 1-CO)-ICN to E-(1-ONO2 , 4-CO)-ICN)) is 1.4, which is considerably lower than the expected ratio of 6 for addition of NO3 in the C1 and C4 carbon positions in the isoprene chain. The MCM produces far more δ-ICN than observed, particularly at night and it also simulates an increase in the daytime δ-ICN that greatly exceeds that seen in the observations. Interestingly, the modelled source of δ-ICN is predominantly during the daytime, due to the presence in Beijing of appreciable daytime amounts of NO3 along with isoprene. The modelled ratios of δ-ICN to propanone nitrate are very different to the observed. This study demonstrates the value of speciated IN measurements to test our understanding of the isoprene degradation chemistry. Our interpretation is limited by the uncertainties in our measurements and relatively small data set, but highlights areas of the isoprene chemistry that warrant further study, in particular the NO3 initiated isoprene degradation chemistry. [ABSTRACT FROM AUTHOR]- Published
- 2020
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47. Nitrous acid (HONO) emissions under real-world driving conditions from vehicles in a UK road tunnel.
- Author
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Kramer, Louisa J., Crilley, Leigh R., Adams, Thomas J., Ball, Stephen M., Pope, Francis D., and Bloss, William J.
- Abstract
Measurements of atmospheric boundary layer nitrous acid (HONO) and nitrogen oxides (NO
x ) were performed in summer 2016 inside a city centre road tunnel in Birmingham, United Kingdom. HONO and NOx mixing ratios were strongly correlated with traffic density, with peak levels observed during the early evening rush hour as a result of traffic congestion in the tunnel. A daytime ΔHONO / ΔNOx ratio of 0.85 % (0.72–1.01 %, 95 % CI) was calculated using reduced major axis regression as the overall fleet-average (comprising 59 % diesel-fuelled vehicles). A comparison with previous tunnel studies and analysis on composition of the fleet suggest that goods-vehicles have a large impact on the overall HONO vehicle emissions; however, new technologies aimed at reducing exhaust emissions, particularly for diesel vehicles, may have reduced the overall direct HONO emission in the UK. This result suggests that in order to accurately represent urban atmospheric emissions and OH radical budget, fleet-weighted HONO / NOx ratios may better quantify HONO vehicle emissions in models, compared with use of a single emissions ratio for all vehicles. The contribution of the direct vehicular source of HONO to total ambient HONO concentrations is also investigated and results show that, in areas with high traffic density, vehicle exhaust emissions are likely to be the dominant HONO source to the boundary layer. [ABSTRACT FROM AUTHOR]- Published
- 2019
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48. Surface–atmosphere exchange of water-soluble gases and aerosols above agricultural grassland pre- and post-fertilisation
- Author
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Ramsay, Robbie, primary, Di Marco, Chiara F., additional, Heal, Mathew R., additional, Twigg, Marsailidh M., additional, Cowan, Nicholas, additional, Jones, Matthew R., additional, Leeson, Sarah R., additional, Bloss, William J., additional, Kramer, Louisa J., additional, Crilley, Leigh, additional, Sörgel, Matthias, additional, Andreae, Meinrat, additional, and Nemitz, Eiko, additional
- Published
- 2018
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49. Evaluation of a low-cost optical particle counter (Alphasense OPC-N2) for ambient air monitoring
- Author
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Crilley, Leigh R., primary, Shaw, Marvin, additional, Pound, Ryan, additional, Kramer, Louisa J., additional, Price, Robin, additional, Young, Stuart, additional, Lewis, Alastair C., additional, and Pope, Francis D., additional
- Published
- 2018
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50. Surface ozone and its precursors at Summit, Greenland: comparison between observations and model simulations
- Author
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Huang, Yaoxian, primary, Wu, Shiliang, additional, Kramer, Louisa J., additional, Helmig, Detlev, additional, and Honrath, Richard E., additional
- Published
- 2017
- Full Text
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