Strong deviations from the NO-NO2-O3 photostationary state in the Pearl River Delta: Indications of active peroxy radical and chlorine radical chemistry

Ma, Yufang; Lu, Keding; Chou, Charles C.‐K.; Li, Xiaoqian; Zhang, Yuanhang

doi:10.1016/j.atmosenv.2017.05.012

Cited by 19 publications

(21 citation statements)

References 57 publications

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“…Next, looking at our modified Leighton ratios, , and using our measured concentrations with the JPL rate constants and solving for RO x we find an average value of 154 pptv. Assuming that this value is off by a factor of 3 as found by Mannschreck et al (2004) this suggests an approximate average range for RO x during our measurement period of 9-50 pptv, and is consistent with several past studies (Cantrell et al, 1993;Hauglustaine et al, 1998;Volz-Thomas et al, 2003;Handisides et al, 2003) that found deviations in the Leighton ratio cannot be explained solely by the reaction of RO x with NO.…”

Section: Ozone Photochemical Productionsupporting

confidence: 92%

“…From our EPA flights, we found a range of values from 1 to 3.3 with an average of 1.87. For measurement conditions similar to ours (predominately rural) the reported values for are between 1 and 3 (Cantrell et al, 1993;Volz-Thomas et al, 2003;Mannschreck et al, 2004); therefore, we feel that the NO 2 measurements reported herein are not likely to be subject to interferences much greater than ∼ 10 %.…”

Section: The Leighton Ratiosupporting

confidence: 54%

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Photochemical production of ozone and emissions of NOx and CH4 in the San Joaquin Valley

et al. 2019

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Abstract. Midday summertime flight data collected in the atmospheric boundary layer (ABL) of California's San Joaquin Valley (SJV) are used to investigate the scalar budgets of NOx, O3, and CH4, in order to quantify the individual processes that control near-surface concentrations, yet are difficult to constrain from surface measurements alone: these include, most importantly, horizontal advection and entrainment mixing from above. The setting is a large mountain–valley system with a small aspect ratio, where topography and persistent temperature inversions impose strong restraints on ABL ventilation. In conjunction with the observed time rates of change this airborne budgeting technique enables us to deduce net photochemical ozone production rates and emission fluxes of NOx and CH4. Estimated NOx emissions from our principal flight domain averaged 216 (±33) t d−1 over six flights in July and August, which is nearly double the California government's NOx inventory for the surrounding three-county region. We consider several possibilities for this discrepancy, including the influence of wildfires, the temporal bias of the airborne sampling, instrumental interferences, and the recent hypothesis presented by Almaraz et al. (2018) of localized high soil NO emissions from intensive agricultural application of nitrogen fertilizers in the region and find the latter to be the most likely explanation. The methane emission average was 438 Gg yr−1 (±143), which also exceeds the emissions inventory for the region by almost a factor of 2. Measured ABL ozone during the six afternoon flights averaged 74 ppb (σ=9.8 ppb). The average midafternoon ozone rise of 2.8 ppb h−1 was found to be comprised of −0.8 ppb h−1 due to horizontal advection of lower O3 levels upwind, −2.5 ppb h−1 from dry deposition loss, −0.5 ppb h−1 from dilution by entrainment mixing, and 6.9 ppb h−1 net in situ photochemical production. The O3 production rates exhibited a dependence on NO2 concentrations (r2=0.35) and no discernible dependence on methane concentrations (r2∼0.02), which are correlated with many of the dominant volatile organic compounds in the region, suggesting that the ozone chemistry was predominantly NOx-limited on the flight days. Additionally, in order to determine the heterogeneity of the different scalars, autocorrelation lengths were calculated for potential temperature (18 km), water vapor (18 km), ozone (30 km), methane (27 km), and NOx (28 km). The spatially diffuse patterns of CH4 and NOx seem to imply a preponderance of broad areal sources rather than localized emissions from cities and/or highway traffic within the SJV.

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Section: Ozone Photochemical Productionsupporting

confidence: 92%

Section: The Leighton Ratiosupporting

confidence: 54%

Photochemical production of ozone and emissions of NOx and CH4 in the San Joaquin Valley

et al. 2019

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“…The reaction rate is for the reaction of NO with HO2 (Burkholder, 2015). A similar approach is found in Mihelcic et al (2003), who used it for calculating what they saw as an upper limit for P(O3), as well as Ma et al (2017). Therefore applying 10 our own calculated production rates added to an estimated photochemical loss of 1ppb/hr(due to photolysis and OH production, and similar to the values Pusede et al (2014) reported from their observations 0.7-1.4 ppb/hr) to get a gross production rate we expect the values for ROx to be a lower limit.…”

Section: Ozone Photochemical Productionmentioning

confidence: 93%

“…This is usually associated with areas where NOx concentrations are not too high like heavily polluted urban centers where there are greater sinks for peroxy radicals and the lose pathway of [OH] with NO2 is significant (Cantrell et al, 1993;Volz-Thomas et al, 2003). Deviations below unity 25 indicate strong local NO emissions or rapid changes in JNO2 so that PSS has not been reached (Ma et al, 2017). Equation 5 Atmos.…”

Section: The Leighton Ratiomentioning

confidence: 99%

Photochemical Production of Ozone and Emissions of NOx and CH4 in the San Joaquin Valley

Trousdell¹,

Caputi²,

Smoot³

et al. 2019

Preprint

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Midday summertime flight data collected in the atmospheric boundary layer (ABL) of California's San Joaquin Valley (SJV) are used to investigate the scalar budgets of NOx, O3, and CH4 in order to quantify the individual processes that control near surface concentrations yet are difficult to constrain from surface measurements alone: most importantly, 10 horizontal advection and entrainment mixing from above. The setting is a large mountain-valley system with a small aspect ratio where topography and persistent temperature inversions impose strong restraints on ABL ventilation. In conjunction with the observed time rate of change this airborne budgeting technique enables us to deduce net photochemical ozone production rates and emission fluxes of NOx and CH4. Measured NOx emissions from our principal flight domain were 216 (± 33) metric tons/ day averaged over six flights in July and August, which is nearly double the California government's 15 NOx inventory for the surrounding three county region. We consider several possibilities for this discrepancy including the influence of wildfires, the temporal bias of the airborne sampling, instrumental interferences, and the recent hypothesis presented by Almaraz et al. (2018) of localized high soil NO emissions from intensive agricultural application of nitrogen fertilizers in the region and find the latter to be the most likely explanation. The methane emission average was 438Gigagrams/ year (± 143), which exceeds an emissions inventory for the region by almost a factor of two as well. Measured 20 ABL ozone during the six afternoon flights averaged 74 ppb ( =9.8 ppb). The average mid-afternoon ozone rise of 2.8 ppb/h was found to be comprised of -0.8 ppb/h due to horizontal advection of lower O3 levels upwind, -2.2 ppb/h from dry deposition loss, -0.5 ppb/h from dilution by entrainment mixing, and 6.7 ppb/h net in-situ photochemical production. The O3 production rates exhibited a dependence on NO2 concentrations (r 2 = 0.35), and no discernible dependence on methane concentrations (r 2 ~ 0.02) which are correlated with many of the dominant VOC's in the region, suggesting that the ozone 25Atmos. Chem. Phys. Discuss., https://doi.

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“…The modelled daytime peak OH value is much higher than those observed daytime maxima at remote forest areas such as Blodgett forest in California (4 × 10 6 molecules cm -3 ) (Mao et al, 2012), boreal forest in Finland (3.5 × 10 6 molecules cm -3 ) (Hens et al, 2014), pine forest in Alabama (1 × 10 6 molecules cm -3 ) (Feiner et al, 2016) and Mount Tai in Central China (5.7 × 10 6 molecules cm -3 ) (Kanaya et al, 2009). Limited studies performed in the PRD region have confirmed the strong atmospheric oxidizing capacity in the polluted atmosphere of this region (Hofzumahaus et al, 2009;Lu et al, 2012;Xue et al, 2016;Ma et al, 2017;Li et al, 2018).…”

Section: Daytime Ohmentioning

confidence: 98%

Low-level isoprene observed during summertime at a forested mountaintop site in southern China: implications for strong regional atmospheric oxidative capacity

Gong

Wang

Zhang

et al. 2018

Preprint

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Abstract. To investigate the atmospheric oxidizing capacity in certain polluted isoprene-rich environments, such as the forests surrounding megacities. Here we present online observations of isoprene and its first-stage oxidation products methyl vinyl ketone (MVK) and methacrolein (MACR) in summer 2016 at a remote, high-altitude mountain forest site (1690&#8201;m&#8201;a.s.l.) to the north of the air-polluted Pearl River Delta (PRD) region in southern China. The observed isoprene level was found to be significantly lower in comparison with other forest sites either in China or around the world, although the sampling site was surrounded with subtropical evergreen broad-leaved trees which are strong isoprene emitters. Also, high (MVK+MACR)/isoprene ratio was observed. Based on the observations, we hypothesized that the lower isoprene levels in the study forest might be attributable to a strong atmospheric oxidative capacity in relation to the elevated regional complex air pollution. High daytime OH and nighttime NO3 radical concentrations estimated by using a photochemical box model incorporating Master Chemical Mechanism (PBM-MCM), as well as calculated short atmospheric reaction times of isoprene and long photochemical age, indicated that the isoprene was rapidly and fully oxidized at this aged atmospheric environment, which confirmed our hypothesis. The study suggests that the complex air pollution in the PRD region has significantly elevated the background atmospheric oxidative capacity of the adjacent forests, and most likely does would probably affect the regional air quality and ecological environment in the long term. The feedback of forest ecosystems to the increasing atmospheric oxidation capacity warrants further studies.

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Strong deviations from the NO-NO2-O3 photostationary state in the Pearl River Delta: Indications of active peroxy radical and chlorine radical chemistry

Cited by 19 publications

References 57 publications

Photochemical production of ozone and emissions of NO<sub><i>x</i></sub> and CH<sub>4</sub> in the San Joaquin Valley

Photochemical production of ozone and emissions of NO<sub><i>x</i></sub> and CH<sub>4</sub> in the San Joaquin Valley

Photochemical Production of Ozone and Emissions of NO<sub>x</sub> and CH<sub>4</sub> in the San Joaquin Valley

Low-level isoprene observed during summertime at a forested mountaintop site in southern China: implications for strong regional atmospheric oxidative capacity

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Strong deviations from the NO-NO2-O3 photostationary state in the Pearl River Delta: Indications of active peroxy radical and chlorine radical chemistry

Cited by 19 publications

References 57 publications

Photochemical production of ozone and emissions of NO&lt;sub&gt;&lt;i&gt;x&lt;/i&gt;&lt;/sub&gt; and CH&lt;sub&gt;4&lt;/sub&gt; in the San Joaquin Valley

Photochemical production of ozone and emissions of NO&lt;sub&gt;&lt;i&gt;x&lt;/i&gt;&lt;/sub&gt; and CH&lt;sub&gt;4&lt;/sub&gt; in the San Joaquin Valley

Photochemical Production of Ozone and Emissions of NO&lt;sub&gt;x&lt;/sub&gt; and CH&lt;sub&gt;4&lt;/sub&gt; in the San Joaquin Valley

Low-level isoprene observed during summertime at a forested mountaintop site in southern China: implications for strong regional atmospheric oxidative capacity

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Photochemical production of ozone and emissions of NO<sub><i>x</i></sub> and CH<sub>4</sub> in the San Joaquin Valley

Photochemical production of ozone and emissions of NO<sub><i>x</i></sub> and CH<sub>4</sub> in the San Joaquin Valley

Photochemical Production of Ozone and Emissions of NO<sub>x</sub> and CH<sub>4</sub> in the San Joaquin Valley