Characterisation of &amp;lt;i&amp;gt;J&amp;lt;/i&amp;gt;(O&amp;lt;sup&amp;gt;1&amp;lt;/sup&amp;gt;D) at Cape Grim 2000–2005

Wilson, Stephen R.

doi:10.5194/acp-15-7337-2015

Cited by 10 publications

(11 citation statements)

References 42 publications

(64 reference statements)

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“…The aerosol optical depth was fixed at 0.15 (from the MAX-DOAS aerosol retrieval), and the total ozone column was fixed at 270 DU, consistent with zenith DOAS measurements using the same MAX-DOAS instrument. The TUV simulated J (O( 1 D)) values were consistent with the empirical parameterisation of Wilson (2015) for J (O( 1 D)) at Cape Grim in north-western Tasmania. The resulting P (OH) diurnal values are presented in Fig.…”

Section: Periods Of Elevated Hono Levelssupporting

confidence: 74%

“…Therefore, the diurnal maximum HONO measured here is unusual for an urban environment and supports the presence of a strong daytime source. The HONO/NO 2 ratio has been used previously to categorise emission sources of HONO, with HONO/NO 2 < 0.01 indicating direct emission dominates HONO production (Wojtal et al, 2011;Hendrick et al, 2014;Qin and Mitchell, 2009;Elshorbany et al, 2009). Given that the HONO/NO 2 ratio is consistently greater than 0.01, it is inferred that the observed HONO cannot be attributed to direct traffic emissions from the adjacent road corridors.…”

Section: Periods Of Elevated Hono Levelsmentioning

confidence: 99%

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Daytime HONO, NO<sub>2</sub> and aerosol distributions from MAX-DOAS observations in Melbourne

et al. 2018

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Toxic nitrogen oxides produced by high temperature combustion are prevalent in urban environments, contributing to a significant health burden. Nitrogen oxides such as NO 2 and HONO in pollution are important for hydroxyl radical (OH) production and overall oxidative capacity in urban environments; however, current mechanisms cannot explain high daytime levels of HONO observed in many urban and rural locations around the world. Here we present HONO, NO 2 and aerosol extinction vertical distributions retrieved from multi-axis differential optical absorption spectroscopy (MAX-DOAS) measurements in suburban Melbourne, which are the first MAX-DOAS results from the Australian continent. Using the optimal estimation algorithm HEIPRO we show that vertical profiles for NO 2 and HONO can be calculated with a low dependence on the retrieval forward model and a priori parameters, despite a lack of independent co-located aerosol or trace gas measurements. Between December 2016 and April 2017 average peak NO 2 values of 8 ± 2 ppb indicated moderate traffic pollution levels, and high daytime peak values of HONO were frequently detected, averaging 220 ± 30 ppt in the middle of the day. HONO levels measured in Melbourne were typically lower than those recorded in the morning in other places around the world, indicating minimal overnight accumulation, but peaked in the middle of the day to be commensurate with midday concentrations in locations with much higher NO 2 pollution. Regular midday peaks in the diurnal cycle of HONO surface concentrations have only previously been reported in rural locations. The HONO measured implies a daytime source term 1 ppb h −1 above the predicted photostationary state (PSS) concentration and represents an OH radical source up to 4 times stronger than from ozone photolysis alone in the lowest 500 m of the troposphere. The dependence of the high midday HONO levels on soil moisture, combined with the observed diurnal and vertical profiles, provides evidence for a strong photoactivated and groundbased daytime HONO source.

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Section: Periods Of Elevated Hono Levelssupporting

confidence: 74%

Section: Periods Of Elevated Hono Levelsmentioning

confidence: 99%

Daytime HONO, NO<sub>2</sub> and aerosol distributions from MAX-DOAS observations in Melbourne

et al. 2018

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“…Dashed lines indicate agreement within ±delta ϕ corresponding to (top) 4 weeks and (middle) 2 weeks in the phase, or agreement within (bottom) ±20%. The cross symbols in Figure (top and middle) indicate the phase angles expected if the seasonal cycle of O 3 were of exactly opposite phase with the photolysis rate of ozone measured at Cape Grim Wilson [] (see Figure ).…”

Section: Resultsmentioning

confidence: 99%

Seasonal cycles of O₃ in the marine boundary layer: Observation and model simulation comparisons

et al. 2016

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We present a two‐step approach for quantitatively comparing modeled and measured seasonal cycles of O3: (1) fitting sine functions to monthly averaged measurements and model results (i.e., deriving a Fourier series expansion of these results) and (2) comparing the phase and amplitude of the statistically significant terms between the models and measurements. Two and only two sine terms are sufficient to quantify the O3 seasonal cycle in the marine boundary layer (MBL) in both the measurements and the model results. In addition to the expected fundamental (one sine cycle per year), a second harmonic term (i.e., two sine cycles per year) is identified as a ubiquitous feature of O3 in the MBL. Three chemistry climate models (Community Atmosphere Model with chemistry, GFDL‐CM3, and GISS‐E2‐R) approximately reproduce many features of the measured seasonal cycles at MBL surface sites throughout the globe, with some notable quantitative disagreements, but give divergent results that do not agree with O3 sonde measurements above the MBL. This disagreement and divergence of results between models indicate that the treatment of the MBL dynamics in the chemistry‐climate models is not adequate to reproduce the isolation of the MBL indicated by the observations. Within the MBL the models more accurately reproduce the second harmonic term than the fundamental term. We attribute the second harmonic term to the second harmonic of opposite phase in the photolysis rate of O3, while the fundamental term evidently has many influences. The parameters derived from the Fourier series expansion of the measurements are quantitative metrics that can serve as the basis for future model‐measurement comparisons.

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“…The photolysis rate proposed for the Southern Hemisphere, i.e. J O 3 = 3 × 10 −5 s −1 (Wilson, 2015), was used, from which P (HO x ) was calculated as follows:…”

Section: Modelling Instantaneous Production Rate Of Omentioning

confidence: 99%

Seasonal influences on surface ozone variability in continental South Africa and implications for air quality

et al. 2018

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Abstract. Although elevated surface ozone (O3) concentrations are observed in many areas within southern Africa, few studies have investigated the regional atmospheric chemistry and dominant atmospheric processes driving surface O3 formation in this region. Therefore, an assessment of comprehensive continuous surface O3 measurements performed at four sites in continental South Africa was conducted. The regional O3 problem was evident, with O3 concentrations regularly exceeding the South African air quality standard limit, while O3 levels were higher compared to other background sites in the Southern Hemisphere. The temporal O3 patterns observed at the four sites resembled typical trends for O3 in continental South Africa, with O3 concentrations peaking in late winter and early spring. Increased O3 concentrations in winter were indicative of increased emissions of O3 precursors from household combustion and other low-level sources, while a spring maximum observed at all the sites was attributed to increased regional biomass burning. Source area maps of O3 and CO indicated significantly higher O3 and CO concentrations associated with air masses passing over a region with increased seasonal open biomass burning, which indicated CO associated with open biomass burning as a major source of O3 in continental South Africa. A strong correlation between O3 on CO was observed, while O3 levels remained relatively constant or decreased with increasing NOx, which supports a VOC-limited regime. The instantaneous production rate of O3 calculated at Welgegund indicated that ∼40 % of O3 production occurred in the VOC-limited regime. The relationship between O3 and precursor species suggests that continental South Africa can be considered VOC limited, which can be attributed to high anthropogenic emissions of NOx in the interior of South Africa. The study indicated that the most effective emission control strategy to reduce O3 levels in continental South Africa should be CO and VOC reduction, mainly associated with household combustion and regional open biomass burning.

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Characterisation of <i>J</i>(O<sup>1</sup>D) at Cape Grim 2000–2005

Cited by 10 publications

References 42 publications

Daytime HONO, NO<sub>2</sub> and aerosol distributions from MAX-DOAS observations in Melbourne

Daytime HONO, NO<sub>2</sub> and aerosol distributions from MAX-DOAS observations in Melbourne

Seasonal cycles of O₃ in the marine boundary layer: Observation and model simulation comparisons

Seasonal influences on surface ozone variability in continental South Africa and implications for air quality

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Characterisation of &lt;i&gt;J&lt;/i&gt;(O&lt;sup&gt;1&lt;/sup&gt;D) at Cape Grim 2000–2005

Cited by 10 publications

References 42 publications

Daytime HONO, NO&lt;sub&gt;2&lt;/sub&gt; and aerosol distributions from MAX-DOAS observations in Melbourne

Daytime HONO, NO&lt;sub&gt;2&lt;/sub&gt; and aerosol distributions from MAX-DOAS observations in Melbourne

Seasonal cycles of O3 in the marine boundary layer: Observation and model simulation comparisons

Seasonal influences on surface ozone variability in continental South Africa and implications for air quality

Contact Info

Product

Resources

About

Characterisation of <i>J</i>(O<sup>1</sup>D) at Cape Grim 2000–2005

Daytime HONO, NO<sub>2</sub> and aerosol distributions from MAX-DOAS observations in Melbourne

Daytime HONO, NO<sub>2</sub> and aerosol distributions from MAX-DOAS observations in Melbourne

Seasonal cycles of O₃ in the marine boundary layer: Observation and model simulation comparisons