NOx versus VOC limitation of O3 production in the Po valley: Local and integrated view based on observations

Spirig, C.; Neftel, A.; Kleinman, Lawrence I.; Hjorth, J.

doi:10.1029/2001jd000561

Cited by 37 publications

(28 citation statements)

References 29 publications

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“…The highest ozone concentration ever reported in the literature has been measured in the metropolitan area of Mexico city with more than 300 ppb (West et al, 2004). Similar concentrations have also been recorded in polluted plumes originating from Beijing (286 ppb, Wang et al, 2006), from Houston (238-251 ppb, Berkowitz et al, 2004, from Mexico city (243-250 ppb, deFoy et al, 2005;Tie et al, 2007;Molina et al, 2007) and from the Po valley in Italy (200 ppb, Spirig et al, 2002). The lack of measurements dedicated to air quality or pollution episodes did not allow the exploration of such phenomenon in Africa.…”

Section: Introductionsupporting

confidence: 53%

What caused extreme ozone concentrations over Cotonou in December 2005?

et al. 2010

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Abstract. This paper reports the first record of extreme ozone measurements in Africa. As part of the AMMA program, the ozone vertical profile recorded on 20 December over Cotonou presents exceptionally high ozone concentrations with up to 295 ppb at 1 km altitude. Retroplumes from the Flexpart model show that the air masses sampled at 1 km over Cotonou on this day came from the burning area situated north-east of Cotonou and passed over Lagos, Nigeria, which is highly impacted by urban pollution. We used the Master Mechanism box model to simulate the chemical composition of the plume during its transit.We find that neither the biomass burning emissions of ozone precursors nor additional urban emissions from Lagos are high enough to simulate more than 120-150 ppb of ozone. The only way to reach almost 300 ppb of ozone within a few hours is to feed the air mass with large amounts of reactive VOCs as those recorded in the vicinity of petrochemical area. Sensitivity tests show that 250-600 ppb of VOCs combined with 35-80 ppb of NO x allow the ozone concentrations to be higher than 250 ppb. Nigeria is the first African country with gas extraction and petrochemical industries, and petrochemical explosions frequently happen in the vicinity of Lagos. The hypothesis of a petrochemical explosion in this area is the most likely scenario which could explain the 295 ppb ozone maximum measured over Cotonou, downwind of Lagos.

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Section: Introductionsupporting

confidence: 53%

What caused extreme ozone concentrations over Cotonou in December 2005?

et al. 2010

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“…These P (O 3 ) are comparable to values of 12-14 ppb h −1 , estimated for ozone production in the New York City plume in July 1996 , and with other high ozone production episodes in the vicinity of US cities (a comparison of five different cities, with a variety of background conditions, is given by Kleinman et al, 2005). Likewise, for the Lombardy region with the city Milan in its centre being one of the most economically important areas in Europe, estimated P (O 3 ) of 5-25 ppb h −1 ' have been reported (May/June 1998; Dommen et al, 2002;Spirig et al, 2002).…”

Section: Observation-based Ozone Production Rates Within the Plumementioning

confidence: 99%

Impact of Manaus City on the Amazon Green Ocean atmosphere: ozone production, precursor sensitivity and aerosol load

et al. 2010

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Abstract. As a contribution to the Large-Scale BiosphereAtmosphere Experiment in Amazonia -Cooperative LBA Airborne Regional Experiment (LBA-CLAIRE-2001) field campaign in the heart of the Amazon Basin, we analyzed the temporal and spatial dynamics of the urban plume of Manaus City during the wet-to-dry season transition period in July 2001. During the flights, we performed vertical stacks of crosswind transects in the urban outflow downwind of Manaus City, measuring a comprehensive set of trace constituents including O 3 , NO, NO 2 , CO, VOC, CO 2 , and H 2 O. Aerosol loads were characterized by concentrations of total aerosol number (CN) and cloud condensation nuclei (CCN), and by light scattering properties. Measurements over pristine rainforest areas during the campaign showed low levCorrespondence to: U. Kuhn (uwe.kuhn@art.admin.ch) els of pollution from biomass burning or industrial emissions, representative of wet season background conditions. The urban plume of Manaus City was found to be joined by plumes from power plants south of the city, all showing evidence of very strong photochemical ozone formation. One episode is discussed in detail, where a threefold increase in ozone mixing ratios within the atmospheric boundary layer occurred within a 100 km travel distance downwind of Manaus. Observation-based estimates of the ozone production rates in the plume reached 15 ppb h −1 .Within the plume core, aerosol concentrations were strongly enhanced, with CN/ CO ratios about one order of magnitude higher than observed in Amazon biomass burning plumes. CN/ CO ratios tended to decrease with increasing transport time, indicative of a significant reduction in particle number by coagulation, and without substantial new particle nucleation occurring within the time/space observed. While in the background atmosphere a large Published by Copernicus Publications on behalf of the European Geosciences Union. 9252 U. Kuhn et al.: Impact of Manaus City on the Amazon Green Ocean atmosphere fraction of the total particle number served as CCN (about 60-80% at 0.6% supersaturation), the CCN/CN ratios within the plume indicated that only a small fraction (16 ± 12 %) of the plume particles were CCN. The fresh plume aerosols showed relatively weak light scattering efficiency. The COnormalized CCN concentrations and light scattering coefficients increased with plume age in most cases, suggesting particle growth by condensation of soluble organic or inorganic species.We used a Single Column Chemistry and Transport Model (SCM) to infer the urban pollution emission fluxes of Manaus City, implying observed mixing ratios of CO, NO x and VOC. The model can reproduce the temporal/spatial distribution of ozone enhancements in the Manaus plume, both with and without accounting for the distinct (high NO x ) contribution by the power plants; this way examining the sensitivity of ozone production to changes in the emission rates of NO x . The VOC reactivity in the Manaus region was dominated by a high burden of biogenic isoprene from the b...

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“…Due to large emissions and low VOC/NO x concentration ratios (as compared to rural background), chemical regimes during ozone pollution episodes have been shown to be generally VOC sensitive for large urban agglomerations: this has been made evident for large North American agglomerations (Los Angeles - Sillman et al, 1997;New York, Philadelphia, Phoenix -Kleinman et al, 2005; Mexico City - Lei et al, 2007), for North-Eastern Asian Megacities during spring (Beijing, Seoul, Tokyo -Guttikunda et al, 2005) and for many European agglomerations as Milano (Spirig et al, 2002;Martilli et al, 2002;Gabusi et al, 2005), Athens (Bossioli et al, 2007), Berlin (Hammer et al, 2002) and Paris Deguillaume et al, 2008). However, for many of these cases, transitions to NO x sensitive chemical regimes occur in the plume of these agglomerations at variable distances.…”

Section: Introductionmentioning

confidence: 99%

A modelling study of photochemical regimes over Europe: robustness and variability

2010

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Abstract. The variability of the relative sensitivity of photochemical ozone formation to volatile organic compounds (VOC) and NO x emissions, the chemical regime, over Europe during summers 2001 to 2003 is simulated with a regional scale transport-chemistry model. The robustness and variability of chemical regimes is shown. A VOC sensitive regime over North-Western Europe and a mainly NO x sensitive regime over the Mediterranean basin and Eastern Europe are found, confirming earlier published results. The chemical regime time variability, its robustness with respect to several environmental factors (seasonality, interannual variability) and with respect to model uncertainty are thoroughly analysed. For the regions with well pronounced chemical regimes over North-Western Europe and the Mediterranean, the chemical regime occurrence only slightly depends on the ozone target considered -daily ozone or O x (= O 3 + NO 2 ) maximum or mean, AOT's, SOMO35, . . . . For these regions, differences between particular years and summer months are weak, day to day variability is significant but does not change the occurrence of one or another chemical regime. On the contrary, over North-Eastern Germany, the chemical regime changes form one day to another and is also dependent on the ozone target chosen. Expected decreases in anthropogenic NO x emissions over Europe since the last and for the next few decades have shifted and will shift chemical regimes to more NO x sensitive. The predictive skill of chemical regime indicator species is made evident at continental scale, extending their spatial range of applicability with respect to earlier studies. Several sensitivity tests were performed in order to account for major sources of model uncertainty. With the Correspondence to: M. Beekmann (matthias.beekmann@lisa.u-pec.fr) exception of regions near ship tracks over the Mediterranean basin, the spatial pattern of chemical regimes appears to be robust with respect to model uncertainty for all cases tested.

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NO_x versus VOC limitation of O₃ production in the Po valley: Local and integrated view based on observations

Cited by 37 publications

References 29 publications

What caused extreme ozone concentrations over Cotonou in December 2005?

What caused extreme ozone concentrations over Cotonou in December 2005?

Impact of Manaus City on the Amazon Green Ocean atmosphere: ozone production, precursor sensitivity and aerosol load

A modelling study of photochemical regimes over Europe: robustness and variability

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