Suchergebnisse

Surface ozone (O3) is a secondary air pollutant, harmful to human health and vegetation. To provide a long-term study of O3 concentrations in Portugal (study period: 2009–2019), a statistical analysis of ozone trends in rural stations (where the highest concentrations can be found) was first performed. Additionally, the effect of nitrogen oxides (NOx) and meteorological variables on O3 concentrations were evaluated in different environments in northern Portugal. A decreasing trend of O3 concentrations was observed in almost all monitoring stations. However, several exceedances to the standard values legislated for human health and vegetation protection were recorded. Daily and seasonal O3 profiles showed high concentrations in the afternoon and summer (for all inland rural stations) or spring (for Portuguese islands). The high number of groups obtained from the cluster analysis showed the difference of ozone behaviour amongst the existent rural stations, highlighting the effectiveness of the current geographical distribution of monitoring stations. Stronger correlations between O3, NO, and NO2 were detected at the urban site, indicating that the O3 concentration was more NOx-sensitive in urban environments. Solar radiation showed a higher correlation with O3 concentration regarding the meteorological influence. The wind and pollutants transport must also be considered in air quality studies. The presented results enable the definition of air quality policies to prevent and/or mitigate unfavourable outcomes from O3 pollution.

none ; 1 ; Authors: Sicard P., De Marco A., Troussier F., Renou C., Vas N., Paoletti E. ; Analyzing hourly ozone data from 214 European background sites over the time period 2000-2010, we demonstrated for the first time that the ozone control measures are effective at rural sites, while ozone concentrations are still increasing in the cities. The Western European Mediterranean basin is expected to be more strongly affected by climate change, including ozone pollution, than most of the other regions of the world. At 58% of the rural sites significant decreases were found resulting in an average - 0.43% per year while an increase was recorded in urban and suburban stations (+0.64%year-1 and+0.46%year-1, respectively). At cities ozone average levels increased, but the peak ozone concentrations decreased. In all station types, a significant reduction in the amplitude of peak ozone concentrations was found at more than 75% of stations (98th percentile,-0.77%year-1; hourly peak,-1.14%year-1 and daily average peak,-0.76%year-1). The peak reduction may largely be attributed to the reduction in NOx and VOC emissions within the European Union which started in the early 1990s. The results suggested a convergence of ozone pollution at remote and urban sites all around the Western European Mediterranean basin. © 2013 Elsevier Ltd. ; none ; 10840/5102 ; De Marco, A. ; De Marco, A.

International audience ; Multi-scale models were applied to assess the surface ozone changes in 2030. Several emission scenarios are considered, ranging from (a) a pessimistic anthropogenic emission increase to (b) an optimistic decrease of emissions, and including (c) a realistic scenario that assumes the implementation of control legislations [CLE]. The two extreme scenarios lead respectively to homogeneous global increase and decrease of surface ozone, whereas low and inhomogeneous changes associated with a slight global increase of ozone are found for the CLE scenario. Over western Europe, for the CLE scenario, the benefit of European emission reduction is significantly counterbalanced by increasing global ozone levels. Considering warmer conditions over Europe and future emission modifications, the human health exposure to surface ozone is found to be significantly worsened. To cite this article: S.

International audience ; Multi-scale models were applied to assess the surface ozone changes in 2030. Several emission scenarios are considered, ranging from (a) a pessimistic anthropogenic emission increase to (b) an optimistic decrease of emissions, and including (c) a realistic scenario that assumes the implementation of control legislations [CLE]. The two extreme scenarios lead respectively to homogeneous global increase and decrease of surface ozone, whereas low and inhomogeneous changes associated with a slight global increase of ozone are found for the CLE scenario. Over western Europe, for the CLE scenario, the benefit of European emission reduction is significantly counterbalanced by increasing global ozone levels. Considering warmer conditions over Europe and future emission modifications, the human health exposure to surface ozone is found to be significantly worsened. To cite this article: S.

International audience ; Multi-scale models were applied to assess the surface ozone changes in 2030. Several emission scenarios are considered, ranging from (a) a pessimistic anthropogenic emission increase to (b) an optimistic decrease of emissions, and including (c) a realistic scenario that assumes the implementation of control legislations [CLE]. The two extreme scenarios lead respectively to homogeneous global increase and decrease of surface ozone, whereas low and inhomogeneous changes associated with a slight global increase of ozone are found for the CLE scenario. Over western Europe, for the CLE scenario, the benefit of European emission reduction is significantly counterbalanced by increasing global ozone levels. Considering warmer conditions over Europe and future emission modifications, the human health exposure to surface ozone is found to be significantly worsened. To cite this article: S.

Four distinct nocturnal surface ozone (NSO) enhancement events were observed, with NSO concentration exceeding 80μg/m3, at multiple ozone (O3) monitoring stations (32 sites) in January, November and December between year 2000–2010, in Portugal. The reasonable explanation for the observed bimodal pattern of surface ozone with enhanced NSO concentration during nighttime has to be transport processes, as the surface ozone production ceases at nighttime. Simultaneous measurements of O3 at multiple stations during the study period in Portugal suggest that horizontal advection alone cannot explain the observed NSO enhancement. Thus, detailed analysis of the atmospheric conditions, simulated with the Weather Research and Forecasting (WRF) model, were performed to evaluate the atmospheric mechanisms responsible for NSO enhancement in the region. Simulations revealed that each event occurred as a result of one or the combination of different atmospheric processes such as, passage of a cold front followed by a subsidence zone; passage of a moving surface trough, with associated strong horizontal wind speed and vertical shear; combination of vertical and horizontal transport at the synoptic scale; formation of a low level jet with associated vertical mixing below the jet stream. The study confirmed that large-scale flow pattern resulting in enhanced vertical mixing in the nocturnal boundary layer, plays a key role in the NSO enhancement events, which frequently occur over Portugal during winter months. © 2016 Elsevier Ltd ; The first author (Pavan S Kulkarni) is thankful to Fundação para a Ciência e a Tecnologia for the grant SFRH/BPD/82033/2011. The paper was partially funded through FEDER (ProgramaOperacionalFactores de Competitividade – COMPETE) and National funding through FCT – Fundação para a Ciência e a Tecnologia in the framework of project FCOMP-01-0124-FEDER-014024 (Refa. FCT PTDC/AAC-CLI/114031/2009).The work is co-funded by the European Union through the European Regional Development Fund, included in the COMPETE 2020 (Operational Program Competitiveness and Internationalization) through the ICT project (UID/GEO/04683/2013) with the reference POCI-01-0145-FEDER-007690. Ashish Sharma was supported by National Science Foundation (NSF) grant number: AGS 0934592, the Notre Dame Environmental Change Initiative and the Center for Sustainable Energy. Authors are thankful to APA (http://qualar.apambiente.pt/) for ozone data, IPMA for meteorological data and NCEP, USA for NNRP/FNL reanalysis data.