© Author(s) 2008. This work is licensed under a Creative Commons License. Atmospheric Chemistry and Physics

Abstract. This study presents an analysis of both MOZAIC profiles above Frankfurt and Lagrangian dispersion model simulations for the 2003 European heat wave. The com-parison of MOZAIC measurements in summer 2003 with the 11-year MOZAIC climatology reflects strong tempera-ture anomalies (exceeding 4◦C) throughout the lower tropo-sphere. Higher positive anomalies of temperature and nega-tive anomalies of both wind speed and relative humidity are found for the period defined here as the heat wave (2–14 August 2003), compared to the periods before (16–31 July 2003) and after (16–31 August 2003) the heat wave. In addi-tion, Lagrangian model simulations in backward mode indi-cate the suppressed long-range transport in the mid- to lower troposphere 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 verti-cal 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 values. This is due to a combination of factors, such as high temperature and radiation, stagna-tion 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 stratospheric-origin ozone tracer has been found for the lower troposphere in this study