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

2011 ◽  
Vol 11 (2) ◽  
pp. 675-688 ◽  
Author(s):  
K. Velchev ◽  
F. Cavalli ◽  
J. Hjorth ◽  
E. Marmer ◽  
E. Vignati ◽  
...  
Keyword(s):  
Surface Ozone ◽  
High Surface ◽  
Western Mediterranean ◽  
Back Trajectory ◽  
Cruise Ship ◽  
Ozone Pollution ◽  
Back Trajectories ◽  
Air Masses ◽  
Ozone Concentrations ◽  
Ozone Levels

Abstract. Ozone, along with other air pollutants, has been measured for two years from a monitoring station placed on a cruise ship that follows a regular track in the Western Mediterranean between April and October. Conditions favouring high ozone levels have been studied by analysis of weather maps and back trajectories. This analysis was focused on a transect over the open sea in the South Western Mediterranean between Tunis and Palma de Mallorca. High ozone levels were found in situations with an anticyclonic circulation over the Western Mediterranean when subsidence brings air masses down from altitudes between 1000 and 3500 m a.s.l. Analysis of composite meteorological maps suggests a relevant contribution of breeze circulation to subsidence during events with high surface ozone concentrations; this points to an important contribution from local ozone formation. A detailed back trajectory analysis of the origin of air masses with high ozone concentrations was carried out for two "hot spots" for ozone pollution, in the Gulf of Genoa and between Naples and Palermo, respectively. The main cause of high ozone levels in the Gulf of Genoa was found to be outflow from the Po Valley and the Genoa area while such episodes along the Naples-Palermo transect were most often associated with trajectories from the Rome or Naples areas. Analysis of the relationship between measured concentrations of Black Carbon and ozone allowed to evaluate the degree of photochemical "ageing" of the air masses encountered along the route of the cruise ship.

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

2010 ◽  
Vol 10 (3) ◽  
pp. 6129-6165 ◽  
Author(s):  
K. Velchev ◽  
F. Cavalli ◽  
J. Hjorth ◽  
E. Marmer ◽  
E. Vignati ◽  
...  
Keyword(s):  
Surface Ozone ◽  
High Surface ◽  
Western Mediterranean ◽  
Back Trajectory ◽  
Minor Importance ◽  
Ozone Pollution ◽  
Back Trajectories ◽  
Air Masses ◽  
Ozone Concentrations ◽  
Ozone Levels

Abstract. Ozone, along with other air pollutants, has been measured for two years from a monitoring station placed on a cruise ship that follows a regular track in the Western Mediterranean between April and October. Conditions favoring high ozone levels have been studied by analysis of weather maps and back trajectories. This analysis was focused on a transect over the open sea in the South Western Mediterranean between Tunis and Palma de Mallorca. High ozone levels were found in situations with an anticyclonic circulation over the Western Mediterranean when subsidence brings air masses down from altitudes between 1000 and 3500 m a.s.l. Analysis of composite meteorological maps suggest a relevant contribution of breeze circulation to subsidence during events with high surface ozone concentrations; this points to an important contribution from local ozone formation. A detailed back trajectory analysis of the origin of air masses with high ozone concentrations was carried out for two "hot spots" for ozone pollution, found along the coast south of Genova and between Napoli and Palermo, respectively. While it was found that the influence of plumes from areas with high pollutant levels might explain most episodes in the Northwestern transect, such "local" influences appeared to be of minor importance within the Napoli-Palermo transect.

scholarly journals Contributions of pollutants from North China Plain to surface ozone at the Shangdianzi GAW Station

2008 ◽  
Vol 8 (19) ◽  
pp. 5889-5898 ◽  
Author(s):  
W. Lin ◽  
X. Xu ◽  
X. Zhang ◽  
J. Tang
Keyword(s):  
North China Plain ◽  
North China ◽  
Surface Ozone ◽  
Surface Wind ◽  
Ozone Pollution ◽  
Ancillary Data ◽  
Ozone Concentrations ◽  
The North ◽  
The North China Plain ◽  
Autumn And Winter

Abstract. Regional ozone pollution has become one of the top environmental concerns in China, especially in those economically vibrant and densely populated regions, such as North China region including Beijing. To address this issue, surface ozone and ancillary data over the period 2004–2006 from the Shangdianzi Regional Background Station in north China were analyzed. Due to the suitable location and valley topography of the site, transport of pollutants from the North China Plain was easily observed and quantified according to surface wind directions. Regional (polluted) and background (clean) ozone concentrations were obtained by detailed statistic analysis. Contribution of pollutants from North China Plain to surface ozone at SDZ was estimated by comparing ozone concentrations observed under SW wind conditions and that under NE wind conditions. The average daily accumulated ozone contribution was estimated to be 240 ppb·hr. The average regional contributions to surface ozone at SDZ from the North China Plain were 21.8 ppb for the whole year, and 19.2, 28.9, 25.0, and 10.0 ppb for spring, summer, autumn, and winter, respectively. The strong ozone contribution in summer led to disappearance of the spring ozone maximum phenomenon at SDZ under winds other than from the NNW to E sectors. The emissions of nitrogen oxide in the North China plain cause a decrease in ozone concentrations in winter.

scholarly journals Influence of Stratospheric Intrusion on the Surface Ozone Levels in India

2012 ◽  
Vol 2012 ◽  
pp. 1-7 ◽  
Author(s):  
Nandita D. Ganguly
Keyword(s):  
Stratospheric Ozone ◽  
Surface Ozone ◽  
High Surface ◽  
Living System ◽  
Transport Processes ◽  
Stratospheric Intrusion ◽  
Life On Earth ◽  
Indian Cities ◽  
Enhanced Surface ◽  
Ozone Levels

The surface ozone levels in some Indian cities have increased significantly in the recent years. Ozone being toxic to the living system and an important contributor to anthropogenic global warming, enhanced surface ozone may have adverse effects on the air quality and climate. Transport of ozone from the stratosphere to the troposphere causes stratospheric ozone to decrease and tropospheric ozone to increase, which can in turn have serious consequences for life on earth. Since stratosphere-troposphere exchange (STE) is an important factor influencing the ozone concentration in the troposphere, this paper investigates probably for the first time the possible contribution of STE events to the observed enhanced surface ozone levels for cities covering from north to south of India. It is concluded that apart from transport processes and in situ photochemical production, STE also influences the observed high-surface ozone levels in Indian cities to a small extent (8%–16%). STE events producing high-surface ozone levels are found to be higher at high latitudes.

scholarly journals North Atlantic Oscillation and tropospheric ozone variability in Europe: model analysis and measurements intercomparison

2012 ◽  
Vol 12 (1) ◽  
pp. 3131-3167 ◽  
Author(s):  
F. S. R. Pausata ◽  
L. Pozzoli ◽  
E. Vignati ◽  
F. J. Dentener
Keyword(s):  
North Atlantic Oscillation ◽  
Atmospheric Circulation ◽  
North Atlantic ◽  
Surface Ozone ◽  
Principal Component ◽  
Northern Europe ◽  
Ozone Pollution ◽  
Ozone Concentrations ◽  
The North ◽  
The North Atlantic

Abstract. Ozone pollution represents a serious health and environmental problem. While ozone pollution is mostly produced by photochemistry in summer, elevated ozone concentrations can also be influenced by long range transport driven by the atmospheric circulation and stratospheric ozone intrusions. We analyze the role of large scale atmospheric circulation variability in the North Atlantic basin in determining surface ozone concentrations. Here, we show, using ground station measurements and a coupled atmosphere-chemistry model simulation for the period 1980–2005, that the North Atlantic Oscillation (NAO) does affect surface ozone concentrations – on average, over 10 ppbv on the monthly mean in southwestern, central and northern Europe – during all seasons except fall. The commonly used NAO index is able to capture the link existing between atmospheric dynamics and surface ozone concentrations in winter and spring but it fails in summer. We find that the first Principal Component, computed from the time variation of the sea level pressure (SLP) field, detects the atmosphere circulation/ozone relationship not only in winter and spring but also during summer, when the atmospheric circulation weakens and regional photochemical processes peak. The first Principal Component of the SLP field could be used as a tool to identify areas more exposed to forthcoming ozone pollution events. Finally, our results suggest that the increasing baseline ozone in western and northern Europe during the 1990s could be related to the prevailing phase of the NAO in that period.

scholarly journals Variability and budget of CO<sub>2</sub> in Europe: analysis of the CAATER airborne campaigns – Part 1: Observed variability

2011 ◽  
Vol 11 (12) ◽  
pp. 5655-5672 ◽  
Author(s):  
I. Xueref-Remy ◽  
C. Messager ◽  
D. Filippi ◽  
M. Pastel ◽  
P. Nedelec ◽  
...  
Keyword(s):  
Standard Deviation ◽  
Fossil Fuel ◽  
Back Trajectory ◽  
Free Troposphere ◽  
The West ◽  
Back Trajectories ◽  
Air Masses ◽  
Airborne Measurements ◽  
Fossil Fuel Emissions

Abstract. Atmospheric airborne measurements of CO2 are very well suited for estimating the time-varying distribution of carbon sources and sinks at the regional scale due to the large geographical area covered over a short time. We present here an analysis of two cross-European airborne campaigns carried out on 23–26 May 2001 (CAATER-1) and 2–3 October 2002 (CAATER-2) over Western Europe. The area covered during CAATER-1 and CAATER-2 was 4° W to 14° E long; 44° N to 52° N lat and 1° E to 17° E long; 46° N to 52° N lat respectively. High precision in situ CO2, CO and Radon 222 measurements were recorded. Flask samples were collected during both campaigns to cross-validate the in situ data. During CAATER-1 and CAATER-2, the mean CO2 concentration was 370.1 ± 4.0 (1-σ standard deviation) ppm and 371.7 ± 5.0 (1-σ) ppm respectively. A HYSPLIT back-trajectories analysis shows that during CAATER 1, northwesterly winds prevailed. In the planetary boundary layer (PBL) air masses became contaminated over Benelux and Western Germany by emissions from these highly urbanized areas, reaching about 380 ppm. Air masses passing over rural areas were depleted in CO2 because of the photosynthesis activity of the vegetation, with observations as low as 355 ppm. During CAATER-2, the back-trajectory analysis showed that air masses were distributed among the 4 sectors. Air masses were enriched in CO2 and CO over anthropogenic emission spots in Germany but also in Poland, as these countries have part of the most CO2-emitting coal-based plants in Europe. Simultaneous measurements of in situ CO2 and CO combined with back-trajectories helped us to distinguish between fossil fuel emissions and other CO2 sources. The ΔCO/ΔCO2 ratios (R2 = 0.33 to 0.88, slopes = 2.42 to 10.37), calculated for anthropogenic-influenced air masses over different countries/regions matched national inventories quite well, showing that airborne measurements can help to identify the origin of fossil fuel emissions in the PBL even when distanced by several days/hundreds of kms from their sources. We have compared airborne CO2 observations to nearby ground station measurements and thereby, confirmed that measurements taken in the lower few meters of the PBL (low-level ground stations) are representative of the local scale, while those located in the free troposphere (FT) (moutain stations) are representative of atmospheric CO2 regionally on a scale of a few hundred kilometers. Stations located several 100 km away from each other differ from a few ppm in their measurements indicating the existence of a gradient within the free troposphere. Observations at stations located on top of small mountains may match the airborne data if the sampled air comes from the FT rather than coming up from the valley. Finally, the analysis of the CO2 vertical variability conducted on the 14 profiles recorded in each campaign shows a variability at least 5 to 8 times higher in the PBL (the 1-σ standard deviation associated to the CO2 mean of all profiles within the PBL is 4.0 ppm and 5.7 ppm for CAATER-1 and CAATER-2, respectively) than in the FT (within the FT, 1-σ is 0.5 ppm and 1.1 ppm for CAATER-1 and CAATER-2, respectively). The CO2 jump between the PBL and the FT equals 3.7 ppm for the first campaign and −0.3 ppm for the second campaign. A very striking zonal CO2 gradient of about 11 ppm was observed in the mid-PBL during CAATER-2, with higher concentrations in the west than in the east. This gradient may originate from differences in atmospheric mixing, ground emission rates or Autumn's earlier start in the west. More airborne campaigns are currently under analysis in the framework of the CARBOEUROPE-IP project to better assess the likelihood of these different hypotheses. In a companion paper (Xueref-Remy et al., 2011, Part 2), a comparison of vertical profiles from observations and several modeling frameworks was conducted for both campaigns.

scholarly journals An investigation on the origin of regional spring time ozone episodes in the Western Mediterranean and Central Europe

2016 ◽  
Author(s):  
Pavlos Kalabokas ◽  
Jens Hjorth ◽  
Gilles Foret ◽  
Gaëlle Dufour ◽  
Maxim Eremenko ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Central Europe ◽  
Wind Velocity ◽  
Geopotential Height ◽  
Surface Ozone ◽  
Western Mediterranean ◽  
Specific Humidity ◽  
Ozone Concentrations ◽  
Ozone Episodes ◽  
Vertical Wind Velocity

Abstract. For the identification of regional spring time ozone episodes, rural EMEP ozone measurements from countries surrounding the Western Mediterranean (Spain, France, Switzerland, Italy, Malta) have been examined with emphasis on periods of high ozone concentrations, according to the daily variation of the afternoon (12:00–18:00) ozone values. For two selected high ozone episodes in April and May 2008, composite NCEP/NCAR reanalysis maps of various meteorological parameters and/or their anomalies (geopotential height, specific humidity, vertical wind velocity omega, vector wind speed and temperature) at various tropospheric pressure levels have been examined together with the corresponding satellite IASI ozone measurements (at 3 and 10 km), CHIMERE simulations, vertical ozone soundings and HYSPLIT back trajectories. The results show that high ozone values are detected in several countries simultaneously over several days. Also, the examined spring ozone episodes over the Western Mediterranean and in Central Europe are linked to synoptic meteorological conditions very similar to those recently observed in summertime ozone episodes over the Eastern Mediterranean (Kalabokas et al., ACP, 2013; Doche et al., ACP, 2014; Kalabokas et al., TellusB, 2015), where the transport of tropospheric ozone-rich air masses through atmospheric subsidence influences significantly the boundary layer and surface ozone concentrations. In particular, the geographic areas with observed tropospheric subsidence seem to be the transition regions between high pressure and low pressure systems. Over these areas, strong gradients of geopotential height and temperature are observed, together with high positive omega vertical wind velocity (downward transport) and low specific humidity (dry conditions), at all examined pressure levels below the altitude of 500 hPa pressure level. During the surface ozone episodes IASI satellite measurements show extended areas of high ozone in the lower and upper troposphere over the low pressure system areas, adjacent to the anticyclones, which influence significantly the boundary layer and surface ozone concentrations within the anticyclones by subsidence and advection in addition to the photochemically produced ozone there, resulting in exceedances of the 60 ppb standard.

scholarly journals North Atlantic Oscillation and tropospheric ozone variability in Europe: model analysis and measurements intercomparison

2012 ◽  
Vol 12 (14) ◽  
pp. 6357-6376 ◽  
Author(s):  
F. S. R. Pausata ◽  
L. Pozzoli ◽  
E. Vignati ◽  
F. J. Dentener
Keyword(s):  
North Atlantic Oscillation ◽  
Atmospheric Circulation ◽  
North Atlantic ◽  
Surface Ozone ◽  
Principal Component ◽  
Northern Europe ◽  
Ozone Pollution ◽  
Ozone Concentrations ◽  
The North ◽  
The North Atlantic

Abstract. Ozone pollution represents a serious health and environmental problem. While ozone pollution is mostly produced by photochemistry in summer, elevated ozone concentrations can also be influenced by long range transport driven by the atmospheric circulation and stratospheric ozone intrusions. We analyze the role of large scale atmospheric circulation variability in the North Atlantic basin in determining surface ozone concentrations over Europe. Here, we show, using ground station measurements and a coupled atmosphere-chemistry model simulation for the period 1980–2005, that the North Atlantic Oscillation (NAO) does affect surface ozone concentrations – on a monthly timescale, over 10 ppbv in southwestern, central and northern Europe – during all seasons except fall. The commonly used NAO index is able to capture the link existing between atmospheric dynamics and surface ozone concentrations in winter and spring but it fails in summer. We find that the first Principal Component, computed from the time variation of the sea level pressure (SLP) field, detects the atmosphere circulation/ozone relationship not only in winter and spring but also during summer, when the atmospheric circulation weakens and regional photochemical processes peak. Given the NAO forecasting skill at intraseasonal time scale, the first Principal Component of the SLP field could be used as an indicator to identify areas more exposed to forthcoming ozone pollution events. Finally, our results suggest that the increasing baseline ozone in western and northern Europe during the 1990s could be related to the prevailing positive phase of the NAO in that period.

scholarly journals Contributions of pollutants from North China Plain to surface ozone at the Shangdianzi GAW station

2008 ◽  
Vol 8 (3) ◽  
pp. 9139-9165 ◽  
Author(s):  
W. Lin ◽  
X. Xu ◽  
X. Zhang ◽  
J. Tang
Keyword(s):  
North China Plain ◽  
North China ◽  
Surface Ozone ◽  
Surface Wind ◽  
Ozone Pollution ◽  
Ancillary Data ◽  
Ozone Concentrations ◽  
The North ◽  
The North China Plain ◽  
Autumn And Winter

Abstract. Regional ozone pollution has become one of the top environmental concerns in China, especially in those economically vibrant and densely populated regions, such as North China region including Beijing. To address this issue, surface ozone and ancillary data over the period 2004–2006 from the Shangdianzi Regional Background Station in north China were analyzed. Due to the suitable location and valley topography of the site, transport of pollutants from the North China Plain was easily observed and quantified according to surface wind directions. Regional (polluted) and natural (clean) background ozone concentrations were obtained by detailed statistic analysis. Contribution of pollutants from North China Plain to surface ozone at SDZ was estimated by comparing ozone concentrations observed under SW wind conditions and that under NE wind conditions. The average daily accumulated ozone contribution was estimated to be 240 ppb·hr. The average regional contributions to surface ozone at SDZ from the North China Plain were 21.8 ppb for the whole year, and 19.2, 28.9, 25.0, and 10.0 ppb for spring, summer, autumn, and winter, respectively. The strong ozone contribution in summer led to disappearance of the spring ozone maximum phenomenon at SDZ under winds other than from the WNN to E sectors. High winter NOx concentrations in the North China Plain caused negative ozone contribution in winter.

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