HONO measurement by differential photolysis

Reed, Chris; Brumby, Charlotte A.; Crilley, Leigh R.; Kramer, Louisa J.; Bloss, William J.; Seakins, Paul W.; Lee, James; Carpenter, Lucy J.

doi:10.5194/amt-9-2483-2016

Cited by 20 publications

(26 citation statements)

References 78 publications

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“…The Integrated Chemistry of Ozone in the Atmosphere (ICOZA) campaign 44 at the Weybourne Atmospheric Observatory (52.95 N, 1.12 E, 45 ) was designed to examine the composition of the atmosphere and local chemical processes at a coastal site in the UK during the summer of 2015 (29 th June to 1 st August). Weybourne is a World Meteorological Organisation (WMO) Global Atmospheric Watch (GAW) programme site.…”

Section: Observationsmentioning

confidence: 99%

Effects of halogens on European air-quality

et al. 2017

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Halogens (Cl, Br) have a profound influence on stratospheric ozone (O). They (Cl, Br and I) have recently also been shown to impact the troposphere, notably by reducing the mixing ratios of O and OH. Their potential for impacting regional air-quality is less well understood. We explore the impact of halogens on regional pollutants (focussing on O) with the European grid of the GEOS-Chem model (0.25° × 0.3125°). It has recently been updated to include a representation of halogen chemistry. We focus on the summer of 2015 during the ICOZA campaign at the Weybourne Atmospheric Observatory on the North Sea coast of the UK. Comparisons between these observations together with those from the UK air-quality network show that the model has some skill in representing the mixing ratios/concentration of pollutants during this period. Although the model has some success in simulating the Weybourne ClNO observations, it significantly underestimates ClNO observations reported at inland locations. It also underestimates mixing ratios of IO, OIO, I and BrO, but this may reflect the coastal nature of these observations. Model simulations, with and without halogens, highlight the processes by which halogens can impact O. Throughout the domain O mixing ratios are reduced by halogens. In northern Europe this is due to a change in the background O advected into the region, whereas in southern Europe this is due to local chemistry driven by Mediterranean emissions. The proportion of hourly O above 50 nmol mol in Europe is reduced from 46% to 18% by halogens. ClNO from NO uptake onto sea-salt leads to increases in O mixing ratio, but these are smaller than the decreases caused by the bromine and iodine. 12% of ethane and 16% of acetone within the boundary layer is oxidised by Cl. Aerosol response to halogens is complex with small (∼10%) reductions in PM in most locations. A lack of observational constraints coupled to large uncertainties in emissions and chemical processing of halogens make these conclusions tentative at best. However, the results here point to the potential for halogen chemistry to influence air quality policy in Europe and other parts of the world.

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Section: Observationsmentioning

confidence: 99%

Effects of halogens on European air-quality

et al. 2017

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“…respectively (Reed et al, 2016a(Reed et al, , 2016b at the (very low) levels present at CVO. The instrument having a zero count rate of ~ 1700 Hz with 1 standard deviation of that signal being ~ 50 Hz this gives a precision of 7.2 pptV for 1 second data with typical sensitivity over the measurement period of 6.9 cps/pptV.…”

Section: Introductionmentioning

confidence: 95%

“…Reed et al, (2016b) showed that thermal interferences in NO 2 using this technique may cause a bias in cold or temperate remote regions, but that in warm regions, such as Cape Verde, the effect is negligible. Photolytic interferences such as BrONO 2 and HONO, and inlet effects may also alter the retrieved NO or NO 2 (Reed et al, 2016a(Reed et al, , 2016b. These effects are considered to be sufficiently small that the concentrations of NO and NO 2 can be determined within an accuracy of 5% and 5.9%…”

Section: Introductionmentioning

confidence: 99%

Evidence for renoxification in the tropical marine boundary layer

Reed¹,

Evans²,

Crilley³

et al. 2017

Preprint

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Abstract. We present two years of NOx observations from the Cape Verde Atmospheric Observatory located in the tropical Atlantic boundary layer. We find NOx mixing ratios peak around solar noon (at 20&#8211;30&#8201;pptV depending on season), which is counter to box model simulations that show a midday minimum due to OH conversion of NO2 to HNO3. Production of NOx via decomposition of organic nitrogen species and the photolysis of HNO3 appear insufficient to provide the observed noon-time maximum. A rapid photolysis of nitrate aerosol to produce HONO and NO2, however, is able to simulate the observed diurnal cycle. This would make it the dominant source of NOx at this remote marine boundary layer site overturning the previous paradigm of transport of organic nitrogen species such as PAN being the dominant source. We show that observed mixing ratios (Nov&#8211;Dec 2015) of HONO at Cape Verde (~&#8201;2.5&#8201;pptV peak at solar noon) are consistent with this route for NOx production. Reactions between the nitrate radical and halogen hydroxides which have been postulated in the literature appear to improve the box model simulation. This rapid conversion of aerosol phase nitrate to NOx changes our perspective of the NOx cycling chemistry in the tropical marine boundary layer, suggesting a more chemically complex environment than previously thought.

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“…Consequently, ANN approach can be a useful alternative to conventional model for investigating formation mechanisms of atmospheric constituents, which are not unequivocally understood. (Cui et al, 2018a) Kensington, UK Jul~Aug 1.05 LOPAP (Lee et al, 2016) Shanghai, China Oct 1.30 LOPAP (Bernard et al, 2016) Xi'an, China Jul~Aug 1.12 LOPAP (Huang et al, 2017) Guangzhou, China Jul 2.80 DOAS (Qin et al, 2009) Beijing, China (Reed et al, 2016) Gyeong-Gi, South Korea Jun 0.65 PPDS-IC Seoul, South Korea Aug 1.23 LP-DOAS (Lee et al, 2005) Seoul, South Korea May~Jul 0.36 HEDS (Song et al, 2009) This study May~Jun 0.93 QC-TILDAS # *Full name 507 # HONO was measured using PPDS-IC technique and their mean concentrations were lower than that of TILDAS. 508 509 510…”

Section: Discussionmentioning

confidence: 99%

“…To easily construct the ANN model, we utilized powerful 'neuralnet' packages in R (Riedmiller and Rprop, 1994;Anastasiadis et al, 2005). Description for ANN models are written in references, and we changed the stepmax from 5 to 10 8 and repetitions from 1 to 3 for making calculation be possible and more accurate.…”

Section: Artificial Neural Network (Ann)mentioning

confidence: 99%

The role of HONO in O3 formation and insight into its formation mechanism during the KORUS-AQ Campaign

Gil

Kim

Lee

et al. 2019

Preprint

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Abstract. Photolysis of nitrous acid (HONO) has long been recognized as an early morning source of OH radicals in urban air, but the detailed mechanism of its formation is still unclear. During the Korea-US Air Quality (KORUS-AQ) campaign, HONO was measured using Quantum Cascade Tunable Diode Laser Absorption Spectroscopy (QC-TDLAS) at Olympic Park in Seoul from 17 May to 10 June, 2016. HONO concentrations ranged from 0.07 ppbv to 3.46 ppbv with an average of 0.93 ppbv. HONO remained high at night from 1 am to 5 am, during which the mean concentration was higher in high-O3 episodes (1.82 ppbv) than non-episode (1.20 ppbv). In the morning, OH budget due to HONO photolysis were higher by 50 % (0.95 pptv) during high-O3 episodes compared to non-episode. Diurnal variations of HOx and O3 simulated by the F0AM model demonstrated a difference of ~ 20 ppbv in daily maximum O3 between the two periods. The HONO concentration increased with relative humidity (RH) until 80 %, of which the highest HONO was associated with the top 10 % NOx, confirming that NOx is a crucial precursor of HONO and its formation is facilitated by humidity. The conversion ratio of NOx to HONO was estimated to be 0.86 × 10−2 h−1 at night and also increased with RH. As surrogate for the catalyst surface, the mass concentrations of black carbon (eBC) and the surface areas of particles smaller than 120 nm showed a tendency for RH similar to conversion ratio. Using an Artificial Neuron Network (ANN) model, HONO concentrations were successfully simulated with measured variables (r = 0.8 for the best suite), among which NOx, surface area, and RH were found to be main factors affecting ambient HONO concentrations with weigh values of 26.2 %, 11.9 %, and 10.6 %, respectively. This study demonstrates the coupling of HONO with HOx-VOCs-O3 cycle in Seoul Metropolitan Areas (SMA) and provides practical evidence for heterogeneous formation of HONO by employing the ANN model to atmospheric chemistry.

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HONO measurement by differential photolysis

Cited by 20 publications

References 78 publications

Effects of halogens on European air-quality

Effects of halogens on European air-quality

Evidence for renoxification in the tropical marine boundary layer

The role of HONO in O<sub>3</sub> formation and insight into its formation mechanism during the KORUS-AQ Campaign

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HONO measurement by differential photolysis

Cited by 20 publications

References 78 publications

Effects of halogens on European air-quality

Effects of halogens on European air-quality

Evidence for renoxification in the tropical marine boundary layer

The role of HONO in O&lt;sub&gt;3&lt;/sub&gt; formation and insight into its formation mechanism during the KORUS-AQ Campaign

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The role of HONO in O<sub>3</sub> formation and insight into its formation mechanism during the KORUS-AQ Campaign