Phenomenology of high-ozone episodes in NE Spain

Research output: Contribution to journalArticlepeer-review

Authors

  • Xavier Querol
  • Gotzon Gangoiti
  • Enrique Mantilla
  • Andrés Alastuey
  • Maria Cruz Minguillón
  • Fulvio Amato
  • Cristina Reche
  • Mar Viana
  • Teresa Moreno
  • Angeliki Karanasiou
  • Ioar Rivas
  • Noemí Pérez
  • Anna Ripoll
  • Mariola Brines
  • Marina Ealo
  • Marco Pandolfi
  • Hong Ku Lee
  • Hee Ram Eun
  • Yong Hee Park
  • Miguel Escudero
  • Amelie Bertrand
  • Nicolas Marchand
  • Andrei Lyasota
  • Bernat Codina
  • Miriam Olid
  • Mireia Udina
  • Bernat Jiménez-Esteve
  • Bernat Bernat Jiménez-Esteve
  • Lucio Alonso
  • Millán Millán
  • Kang Ho Ahn

Colleges, School and Institutes

External organisations

  • Spanish Research Council (IDÆA-CSIC)
  • Universidad del País Vasco UPV/EHU
  • Parque Tecnológico
  • Hanyang University
  • Academia General Militar
  • King Abdulaziz University, Department of Environmental Sciences, Center of Excellence in Environmental Studies, Jeddah 21589, Saudi Arabia
  • LCE
  • Universitat Autònoma de Barcelona

Abstract

Ground-level and vertical measurements (performed using tethered and non-tethered balloons), coupled with modelling, of ozone (O3), other gaseous pollutants (NO, NO2, CO, SO2) and aerosols were carried out in the plains (Vic Plain) and valleys of the northern region of the Barcelona metropolitan area (BMA) in July 2015, an area typically recording the highest O3 episodes in Spain. Our results suggest that these very high O3 episodes were originated by three main contributions: (i) the surface fumigation from high O3 reservoir layers located at 1500-3000 mg-a.g.l. (according to modelling and non-tethered balloon measurements), and originated during the previous day(s) injections of polluted air masses at high altitude; (ii) local/regional photochemical production and transport (at lower heights) from the BMA and the surrounding coastal settlements, into the inland valleys; and (iii) external (to the study area) contributions of both O3 and precursors. These processes gave rise to maximal O3 levels in the inland plains and valleys northwards from the BMA when compared to the higher mountain sites. Thus, a maximum O3 concentration was observed within the lower tropospheric layer, characterised by an upward increase of O3 and black carbon (BC) up to around 100-200 m a.g.l. (reaching up to 300 μg mg-3 of O3 as a 10 s average), followed by a decrease of both pollutants at higher altitudes, where BC and O3 concentrations alternate in layers with parallel variations, probably as a consequence of the atmospheric transport from the BMA and the return flows (to the sea) of strata injected at certain heights the previous day(s). At the highest altitudes reached in this study with the tethered balloons (900-1000 m a.g.l.) during the campaign, BC and O3 were often anti-correlated or unrelated, possibly due to a prevailing regional or even hemispheric contribution of O3 at those altitudes. In the central hours of the days a homogeneous O3 distribution was evidenced for the lowest 1 km of the atmosphere, although probably important variations could be expected at higher levels, where the high O3 return strata are injected according to the modelling results and non-tethered balloon data. Relatively low concentrations of ultrafine particles (UFPs) were found during the study, and nucleation episodes were only detected in the boundary layer. Two types of O3 episodes were identified: type A with major exceedances of the O3 information threshold (180 μg mg-3 on an hourly basis) caused by a clear daily concatenation of local/regional production with accumulation (at upper levels), fumigation and direct transport from the BMA (closed circulation); and type B with regional O3 production without major recirculation (or fumigation) of the polluted BMA/regional air masses (open circulation), and relatively lower O3 levels, but still exceeding the 8 h averaged health target. To implement potential O3 control and abatement strategies two major key tasks are proposed: (i) meteorological forecasting, from June to August, to predict recirculation episodes so that NOx and VOC abatement measures can be applied before these episodes start; (ii) sensitivity analysis with high-resolution modelling to evaluate the effectiveness of these potential abatement measures of precursors for O3 reduction.

Details

Original languageEnglish
Pages (from-to)2817-2838
Number of pages22
JournalAtmospheric Chemistry and Physics
Volume17
Issue number4
Publication statusPublished - 23 Feb 2017

ASJC Scopus subject areas