Ozone over the Western Mediterranean Sea – results from two years of shipborne measurements

Velchev, K.; Cavalli, F.; Hjorth, J.; Marmer, Elina; Vignati, E.; Dentener, Frank; Raes, Frank

doi:10.5194/acp-11-675-2011

Cited by 54 publications

(45 citation statements)

References 25 publications

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“…Gerasopoulos et al (2006) found that 7-yr monthly average surface ozone measured in Crete (Eastern Mediterranean) exceeded 55 ppbv during the summer months, compared with less than 40 ppbv in winter. In the western Mediterranean basin, ozone enhancements have also been reported, with surface summertime average ozone concentrations at rural stations in Italy, eastern Spain, and Malta of more than 55-60 ppbv (Paoletti, 2006;Millan et al, 2000;Nolle et al, 2002), and up to 80 ppbv ozone has been observed by ship at the northern edge of the basin, close to the coasts of the south of France and northwest Italy during summer (Velchev et al, 2011). The prevalence of mountainous coastal topography leads to upslope winds during the daytime encouraging the formation of sea breeze circulation patterns (Millan et al, 1997).…”

Section: Introductionmentioning

confidence: 94%

“…Ozone at the surface is harmful to health (Levy et al, 2001;Gryparis et al, 2004;Ito et al, 2005), and damages vegetation, reducing crop yields (Fuhrer, 2009;Van Dingenen et al, 2009;Hollaway et al, 2012) and inhibits the terrestrial CO 2 sink (Sitch et al, 2007;Collins et al, 2010). Tropospheric ozone is produced in-situ through sunlight-initiated oxidation of volatile organic compounds (VOCs) in the presence of nitrogen oxides (NO x ) (Volz and Kley, 1988;Staehelin et al, 1994). Observations show that the Mediterranean troposphere exhibits a marked enhancement in summertime ozone, which maximises over the eastern basin (Butkovic et al, 1990;Varotsos and Cracknell, 1993;Kalabokas and Bartzis, 1998;Kalabokas et al, 2000Kalabokas et al, , 2007Kouvarakis et al, 2000Kouvarakis et al, , 2002Lelieveld and Dentener, 2000;Kourtidis et al, 2002;Lelieveld et al, 2002; Published by Copernicus Publications on behalf of the European Geosciences Union.…”

Section: Introductionmentioning

confidence: 99%

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The Mediterranean summertime ozone maximum: global emission sensitivities and radiative impacts

et al. 2013

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The Mediterranean troposphere exhibits a marked and localised summertime ozone maximum, which has the potential to strongly impact regional air quality and radiative forcing. The Mediterranean region can be perturbed by long-range pollution import from Northern Europe, North America and Asia, in addition to local emissions, which may all contribute to regional ozone enhancements. We exploit ozone profile observations from the Tropospheric Emission Spectrometer (TES) and the Global Ozone Monitoring Experiment-2 (GOME-2) satellite instruments, and an offline 3-D global chemical transport model (TOMCAT) to investigate the geographical and vertical structure of the summertime tropospheric ozone maximum over the Mediterranean region. We show that both TES and GOME-2 are able to detect enhanced levels of ozone in the lower troposphere over the region during the summer. These observations, together with surface measurements, are used to evaluate the TOMCAT model's ability to capture the observed ozone enhancement. The model is used to quantify sensitivities of the ozone maximum to anthropogenic and natural volatile organic compound (VOC) emissions, anthropogenic NO_x emissions, wildfire emissions and long-range import of ozone and precursors. Our results show a dominant sensitivity to natural VOC emissions in the Mediterranean basin over anthropogenic VOC emissions. However, local anthropogenic NO_x emissions are result in the overall largest sensitivity in near-surface ozone. We also show that in the lower troposphere, global VOC emissions account for 40% of the ozone sensitivity to VOC emissions in the region, whereas, for NO_x the ozone sensitivity to local sources is 9 times greater than that for global emissions at these altitudes. However, in the mid and upper troposphere ozone is most sensitive to non-local emission sources. In terms of radiative effects on regional climate, ozone contributions from non-local emission sources are more important, as these have a larger impact on ozone in the upper troposphere where its radiative effects are larger, with Asian monsoon outflow having the greatest impact. Our results allow improved understanding of the large-scale processes controlling air quality and climate in the region of the Mediterranean basin

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Section: Introductionmentioning

confidence: 94%

Section: Introductionmentioning

confidence: 99%

The Mediterranean summertime ozone maximum: global emission sensitivities and radiative impacts

et al. 2013

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“…These plumes are generally VOC-sensitive, in contrast to the likely NO x -sensitive conditions over the rest of the Mediterranean. Velchev et al (2011) report instances of decreased O 3 coincident with high aerosols found during ship-based measurements in the western Mediterranean, which they attribute to removal of O 3 by NO x in high-emission regions near harbours. The observed instances were found immediately downwind of Marseilles and Barcelona, but relatively close to the urban centres.…”

Section: Voc and No X Sensitivitymentioning

confidence: 99%

Implementation and evaluation of online gas-phase chemistry within a regional climate model (RegCM-CHEM4)

et al. 2012

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Abstract. The RegCM-CHEM4 is a new online climatechemistry model based on the International Centre for Theoretical Physics (ICTP) regional climate model (RegCM4). Tropospheric gas-phase chemistry is integrated into the climate model using the condensed version of the Carbon Bond Mechanism (CBM-Z; Zaveri and Peters, 1999) with a fast solver based on radical balances. We evaluate the model over continental Europe for two different time scales: (1) an event-based analysis of the ozone episode associated with the heat wave of August 2003 and (2) a climatological analysis of a six-year simulation (2000)(2001)(2002)(2003)(2004)(2005). For the episode analysis, model simulations show good agreement with European Monitoring and Evaluation Programme (EMEP) observations of hourly ozone over different regions in Europe and capture ozone concentrations during and after the summer 2003 heat wave event. For long-term climate simulations, the model captures the seasonal cycle of ozone concentrations with some over prediction of ozone concentrations in non-heat wave summers. Overall, the ozone and ozone precursor evaluation shows the feasibility of using RegCM-CHEM4 for decadal-length simulations of chemistry-climate interactions.

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“…However, at the present time we lack an extensive representation of the mean load, distribution, and physico-chemical and optical properties of the atmospheric aerosols, and the trace gases distribution, in the whole region, in particular over the remote sea. In addition, there is a significant lack of observations over some key areas, as for example the Gulf of Genoa, directly under the influence of the outflow from the highly polluted Po Valley (Velchev et al, 2011).…”

Section: DI Biagio Et Al: Continental Pollution In the Western Mementioning

confidence: 99%

“…In particular, the interaction between synoptic circulation and local dynamics, such as orography and sea breezes, has been shown to strongly impact the vertical distribution, layering, and aging of particles along coastal regions (e.g. Millan et al, 1997;Gangoiti et al, 2001;Pérez et al, 2004;Velchev et al, 2011).…”

Section: DI Biagio Et Al: Continental Pollution In the Western Mementioning

confidence: 99%

Continental pollution in the western Mediterranean basin: vertical profiles of aerosol and trace gases measured over the sea during TRAQA 2012 and SAFMED 2013

et al. 2015

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Abstract. In this study we present airborne observations of aerosol and trace gases obtained over the sea in the western Mediterranean basin during the TRAQA (TRansport and Air QuAlity) and SAFMED (Secondary Aerosol Formation in the MEDiterranean) campaigns in summer 2012 and 2013. A total of 23 vertical profiles were measured up to 5000 m above sea level over an extended area (40-45 • N and 2 • W-12 • E) including the Gulf of Genoa, southern France, the Gulf of Lion, and the Spanish coast. During TRAQA and SAFMED the study area experienced a wide range of meteorological conditions which favoured pollution export from different sources located around the basin. Also, several events of dust outflows were measured during the campaigns. Observations from the present study show that continental pollution largely affects the western Mediterranean both close to coastal regions and in the open sea as far as ∼ 250 km from the coastline. The measured aerosol scattering coefficient varies between ∼ 20 and 120 Mm −1 , while carbon monoxide (CO) and ozone (O 3 ) mixing ratios are in the range of 60-165 and 30-85 ppbv, respectively. Pollution reaches 3000-4000 m in altitude and presents a very complex and highly stratified structure characterized by fresh and aged layers both in the boundary layer and in the free troposphere. Within pollution plumes the measured particle concentration in the Aitken (0.004-0.1 µm) and accumulation (0.1-1.0 µm) modes is between ∼ 30 and 5000-6000 scm −3 (standard cm −3 ), which is comparable to the aerosol concentration measured in continental areas under pollution conditions. Additionally, our measurements indicate the presence of highly concentrated Aitken layers (10 000-15 000 scm −3 ) observed both close to the surface and in the free troposphere, possibly linked to the influence of new particle formation (NPF) episodes over the basin.

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Ozone over the Western Mediterranean Sea – results from two years of shipborne measurements

Abstract: Abstract. Ozone, along with other air

Cited by 54 publications

References 25 publications

The Mediterranean summertime ozone maximum: global emission sensitivities and radiative impacts

The Mediterranean summertime ozone maximum: global emission sensitivities and radiative impacts

Implementation and evaluation of online gas-phase chemistry within a regional climate model (RegCM-CHEM4)

Continental pollution in the western Mediterranean basin: vertical profiles of aerosol and trace gases measured over the sea during TRAQA 2012 and SAFMED 2013

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