Air pollution during the 2003 European heat wave as seen by MOZAIC airliners

M. Tressol, C. Ordonez, R. Zbinden, V. Thouret, C. Mari, P. Nedelec, J.-P. Cammas, H. Smit, H.-W. Patz, A. Volz-Thomas
2007 Atmospheric Chemistry and Physics Discussions  
This study presents an analysis of both MOZAIC profiles above Frankfurt and Lagrangian dispersion model simulations for the 2003 European heat wave. The comparison of MOZAIC measurements in summer 2003 with the 11-year MOZAIC climatology reflects strong temperature anomalies (exceeding 4 • C) throughout the lower tro-5 posphere. Higher positive anomalies of temperature and negative anomalies of both wind speed and relative humidity are found for the period defined here as the heat wave (2-14
more » ... ust 2003), compared to the periods before (16-31 July 2003) and after (16-31 August 2003) the heat wave. In addition, Lagrangian model simulations in backward mode indicate the suppressed long-range transport in the mid-to lower tro-10 posphere and the enhanced southern origin of air masses for all tropospheric levels during the heat wave. Ozone and carbon monoxide also present strong anomalies (both ∼ +40 ppbv) during the heat wave, with a maximum vertical extension reaching 6 km altitude around 11 August 2003. Pollution in the planetary boundary layer (PBL) is enhanced during the day, with ozone mixing ratios two times higher than climatological 15 values. This is due to a combination of factors, such as high temperature and radiation, stagnation of air masses and weak dry deposition, which favour the accumulation of ozone precursors and the build-up of ozone. A negligible role of a stratosphericorigin ozone tracer has been found for the lower troposphere in this study. From 29 July to 15 August 2003 forest fires burned around 0.3×10 6 ha) in Portugal and added 20 to atmospheric pollution in Europe. Layers with enhanced CO and NO y mixing ratios, probably advected from Portugal, were crossed by the MOZAIC aircraft in the free troposphere over Frankfurt. A series of forward and backward Lagrangian model simulations have been performed to investigate the origin of these anomalies. During the whole heat wave, European anthropogenic emissions present the strongest contribu-25 tion to the measured CO levels in the lower troposphere (near 30%). This source is followed by Portuguese forest fires which affect the lower troposphere after Abstract Introduction Conclusions References Tables Figures Back Close Full Screen / Esc Printer-friendly Version Interactive Discussion EGU bution reaches 35% during the affected period. Anthropogenic CO of North American origin only marginally influences CO levels over Europe during that period. 20
doi:10.5194/acpd-7-15911-2007 fatcat:akrcrlt2pzb6fb4553f4cbjkvy