Influence of weekdays, weekends and bandhas on surface ozone in Kathmandu valley

Pudasainee, Deepak; Sapkota, Balkrishna; Bhatnagar, Amit; Kim, Seong Heon; Seo, Yong Chil

doi:10.1016/j.atmosres.2009.09.007

Cited by 22 publications

(24 citation statements)

References 35 publications

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“…There should be a difference between weekday and weekend VOCs, and the change of VOC / NO x mixing ratios should also change according to the variation in their sources in this fast developing area, as in other regions of the world (Atkinson-Palombo et al, 2006;Sadanaga et al, 2008;Shao et al, 2009;Pudasainee et al, 2010). However, direct VOC measurements were not used in our analysis.…”

Section: Decrease In No X and Co On The Weekendmentioning

confidence: 99%

“…The ozone level ranged from 22.65 ppb (QA) to 35.65 ppb (LF), whereas NO x remained at a high concentration. The (Stephens et al, 2008), France (Pont et al, 2001), Japan (Sadanaga et al, 2008), Nepal (Pudasainee et al, 2010) and Shanghai (Tang et al, 2009), which all had maximum ozone levels on Sunday. The detailed interpretations will be discussed in the next section.…”

Section: The Weekly Cycle Of Surface Ozone Concentrationmentioning

confidence: 99%

“…However, the study of the OWE in Asia is limited due to the small number of observation sites compared to America and Europe. Only few investigations have been conducted in Shanghai (Tang et al, 2008), the Kathmandu Valley (Pudasainee et al, 2010), Taiwan and Japan (Tasi, 2005;Sadanaga et al, 2008).…”

Section: Introductionmentioning

confidence: 99%

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Ozone weekend effects in the Beijing–Tianjin–Hebei metropolitan area, China

Wang

et al. 2014

Atmos. Chem. Phys.

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Abstract. The ozone weekend effect (OWE) was first investigated in the metropolitan area of Beijing-Tianjin-Hebei (BTH), China, using in situ measurements from the Atmospheric Environment Monitoring Network from July 2009 to August 2011. The results indicate that there is an obvious weekly periodical variation in the surface ozone concentration. There is a lower ozone concentration from Wednesday to Friday (weekday) and a higher concentration from Saturday to Monday (weekend) at all the locations of the study. NO x also displays a weekly cycle, with the maximum level occurring on weekdays and the minimum level on weekends, especially later on Sunday night and early Monday morning. This pattern may be responsible for the higher concentration of ozone on weekends. Additionally, the vertical variations in O 3 and NO x from the 8 m, 47 m, 120 m and 280 m observation platforms on the 325 m Beijing meteorological tower displayed obvious weekly cycles that corresponded to the surface results.A smaller decrease in volatile organic compounds (VOCs; using CO as a proxy) and much lower NO x concentrations on the weekend may lead to higher VOC / NO x ratio, which can enhance the ozone production efficiency in VOC-limited regime areas. Additionally, a clear weekly cycle in the fine aerosol concentration was observed, with maximum values occurring on weekdays and minimum values occurring on weekends. Higher concentrations of aerosol on weekdays can reduce the UV radiation flux by scattering or absorbing, which leads to a decrease in the ozone production efficiency. A significant weekly cycle in UV radiation, consistent with the aerosol concentration, was discovered at the Beijing meteorological tower site (BJT), validating the assumption. A comprehensive understanding of the ozone weekend effect in the BTH area can provide deep insights into controlling photochemical pollution.

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Section: Decrease In No X and Co On The Weekendmentioning

confidence: 99%

Section: The Weekly Cycle Of Surface Ozone Concentrationmentioning

confidence: 99%

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Ozone weekend effects in the Beijing–Tianjin–Hebei metropolitan area, China

Wang

et al. 2014

Atmos. Chem. Phys.

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“…As the day progresses, sunlight intensity becomes higher, increasing the radical concentration and hence the NO to NO 2 oxidation rate from the reaction of NO with peroxy radicals. Subsequent photolysis of NO 2 leads to increased O 3 throughout the day (Pudasainee et al, 2010), with the rate of O 3 production being a function of NO x and VOC levels as well as sunlight intensity. Recent studies of annually averaged daily VOC mixing ratios in London from the 191 m high BT (British Telecom) Tower have shown that benzene and toluene mixing ratios typically display two daytime maxima: one occurring around 09:00 and a second, larger peak occurring between 18:00 and 21:00 local time and coinciding with morning and evening peak traffic periods (Langford et al, 2010;Lee et al, 2015).…”

Section: Interpretation Of Temporal Trace Gas Profilesmentioning

confidence: 99%

Airborne determination of the temporo-spatial distribution of benzene, toluene, nitrogen oxides and ozone in the boundary layer across Greater London, UK

et al. 2015

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Abstract. Highly spatially resolved mixing ratios of benzene and toluene, nitrogen oxides (NO x ) and ozone (O 3 ) were measured in the atmospheric boundary layer above Greater London during the period 24 June to 9 July 2013 using a Dornier 228 aircraft. Toluene and benzene were determined in situ using a proton transfer reaction mass spectrometer (PTR-MS), NO x by dual-channel NO x chemiluminescence and O 3 mixing ratios by UV absorption.Average mixing ratios observed over inner London at 360 ± 10 m a.g.l. were 0.20 ± 0.05, 0.28 ± 0.07, 13.2 ± 8.6, 21.0 ± 7.3 and 34.3 ± 15.2 ppbv for benzene, toluene, NO, NO 2 and NO x respectively. Linear regression analysis between NO 2 , benzene and toluene mixing ratios yields a strong covariance, indicating that these compounds predominantly share the same or co-located sources within the city.Average mixing ratios measured at 360 ± 10 m a.g.l. over outer London were always lower than over inner London. Where traffic densities were highest, the toluene / benzene (T / B) concentration ratios were highest (average of 1.8 ± 0.5 ppbv ppbv −1 ), indicative of strong local sources. Daytime maxima in NO x , benzene and toluene mixing ratios were observed in the morning (∼ 40 ppbv NO x , ∼ 350 pptv toluene and ∼ 200 pptv benzene) and in the mid-afternoon for ozone (∼ 40 ppbv O 3 ), all at 360 ± 10 m a.g.l.

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“…The weekly pattern of air pollutants is of general interest, and studies have been carried out in North America (Blanchard and Tanenbaum, 2003;Pun et al, 2003;Murphy et al, 2007;Koo et al, 2012), Europe (Brönnimann and Neu, 1997;Pont and Fontan, 2001;Jenkin et al, 2002 Paschalidou andKassomenos, 2004), Mexico (Stephens et al, 2008), Japan (Sadanaga et al, 2012), India (Debaje and Kakade, 2006;Pudasainee et al, 2010;Srimuruganandam and Nagendra, 2011) and Egypt (Khoder et al, 2009). Some of these studies analysed the influence of meteorological parameters, such as temperature and radiation, on the occurrence of the weekend effect (Brönnimann and Neu, 1997).…”

Section: Introductionmentioning

confidence: 99%

Weekend-Weekday Effect Assessment for O3, NOx, CO and PM10 in Andalusia, Spain (2003-2008)

Adame

Hernández-Ceballos

Sorribas

et al. 2014

Aerosol Air Qual. Res.

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Day-of-week variations in O 3 , NO x , CO and PM 10 were analysed in the southwestern region of Europe (specifically Andalusia, Spain) using hourly concentrations collected at 43 stations (representing five typologies) over 6 years (2003)(2004)(2005)(2006)(2007)(2008). This area has air pollution problems, and the study of the weekend effect is used as a tool to plan future strategies for emissions reductions. Maximum daily 8 h averages for O 3 , daily 90 th percentiles for NO, NO 2 and PM 10 and mean daily values for CO were calculated and used to assess the weekend effect by applying three different metrics: weekly evolution, weekend-weekday differences and average daily difference between weekends minus workdays. Based on daily parameters and weekend-weekday differences, all the measured air pollutants exhibited clearly reduced concentrations (oscillating between 25 to 85%) on weekends, mainly at urban and suburban stations, with the exception of O 3 (less than 10 µg/m 3 ). This decrease on weekend days was mostly observed for NO, NO 2 and PM 10 at urban stations, while differences at industrial and rural stations were low or null. CO showed a low reduction. Using the daily cycle of differences (weekend minus workdays) as a reference, positive deviations were observed at night and negative differences were observed during the daytime for NO, NO 2 and PM 10 at urban traffic, urban background and suburban background sites. A reduction in morning rush hour traffic during the weekends was reflected in the data from urban stations, which showed a decrease of up to 50, 15 and 12 µg/m 3 for NO, NO 2 and PM 10 , respectively. An opposite daily behaviour was found for ozone, which showed an increase at urban area sites of up to 15 µg/m 3 in the early morning.

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Influence of weekdays, weekends and bandhas on surface ozone in Kathmandu valley

Cited by 22 publications

References 35 publications

Ozone weekend effects in the Beijing–Tianjin–Hebei metropolitan area, China

Ozone weekend effects in the Beijing–Tianjin–Hebei metropolitan area, China

Airborne determination of the temporo-spatial distribution of benzene, toluene, nitrogen oxides and ozone in the boundary layer across Greater London, UK

Weekend-Weekday Effect Assessment for O3, NOx, CO and PM10 in Andalusia, Spain (2003-2008)

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