European surface ozone in the extreme summer 2003

Abstract

1] Measurements of ozone and other trace species in the European EMEP network in 2003 are presented. The European summer of 2003 was exceptionally warm, and the surface ozone data for central Europe show the highest values since the end of the 1980s. The 95th percentiles of daily maximum hourly ozone concentrations in 2003 were higher than the corresponding parameter measured in any previous year at many sites in France, Germany, Switzerland and Austria. In this paper we argue that a number of positive feedbacks between the weather conditions and ozone contributed to the elevated surface ozone. First, we calculated an extended residence time of air parcels in the atmospheric boundary layer for several sites in central Europe. Second, we show that it is likely that extensive forest fires on the Iberian Peninsula, resulting from the drought and heat, contributed to the peak ozone values in north Europe in August. Third, regional-scale model calculations indicate that enhanced levels of biogenic isoprene could have contributed up to 20% of the peak ozone concentrations. Measurements indicate elevated concentrations of isoprene compared to previous years. Sensitivity runs with a global chemical transport model showed that a reduction in the surface dry deposition due to drought and the elevated air temperature both could have contributed significantly to the enhanced ozone concentrations. Because of climate change, such heat waves may occur more frequently in the future and may gradually overshadow the effect of reduced emissions from anthropogenic sources of VOC and NO x in controlling surface ozone.

Introduction: European Integrated Project on Aerosol Cloud Climate and Air Quality interactions (EUCAARI) – integrating aerosol research from nano to global scales

“…In a EUCAARI-related study Solberg et al (2008), argued based on atmospheric trace species measurements in the boundary layer over Europe during the exceptionally warm summer of 2003, that a number of positive feedbacks between the weather conditions and atmospheric composition contributed to the elevated surface ozone observed. The findings are also relevant for the PM concentrations.…”

Global model simulations of air pollution during the 2003 European heat wave

“…Another simulation with standard dry deposition and anthropogenic VOC emissions increased by 30%, in order to account for the extra evaporation of anthropogenic VOCs by the exceptional temperatures, produced nearly identical results. A set of sensitivity model runs with the Oslo CTM2 at spectral resolution T42 (2.8 • ×2.8 • ) also proved that dry deposition was a critical parameter for surface ozone during that period (Solberg et al, 2008). They turned off dry deposition over a large fraction of Europe yielding an increase in peak ozone levels of more than 20%.…”

“…They emphasised that the entrainment of air from the residual layer aloft, polluted on a regional scale, controlled the abundance of anthropogenic volatile organic compounds (VOCs) and photochemical products. In addition, increased temperatures and solar radiation favoured biogenic emissions of isoprene as observed in Southeast England (Lee et al, 2006) and South Eastern France (Solberg et al, 2008), with a potential for enhanced ozone chemistry in the boundary layer. The high levels of atmospheric pollutants had important consequences for human health.…”

“…Vautard et al, 2005;Guerova and Jones, 2007;Solberg et al, 2008). This study presents global model simulations for that period carried out within the Global Reactive Gases (GRG) subproject of GEMS (Global Earth-system Monitoring using Space and in-situ data) and comparisons with MOZAIC vertical profiles over three European airports.…”

“…Smaller anomalies were found for the periods before (16-31 July 2003) and after (16-31 August 2003) the heat wave. The analysis of simulations carried out with the Lagrangian particle dispersion model FLEX-PART indicate extended residence time of air parcels in the European boundary layer (Solberg et al, 2008), suppressed long-range transport in the mid-to lower troposphere and enhanced southern origin of air masses for all tropospheric levels during the heat wave period (Tressol et al, 2008). The unprecedented 2003 heat wave and in particular the first half of August had a major impact on excessive mortality rates throughout Europe.…”