Atmospheric Chemistry and Physics Discussions www.atmos-chem-phys-discuss.net 1680-7367 1680-7375 3 1 2003 10.5194/acpd-3-107-2003 http://www.atmos-chem-phys-discuss.net/3/107/2003/ http://www.atmos-chem-phys-discuss.net/3/107/2003/acpd-3-107-2003.html http://www.atmos-chem-phys-discuss.net/3/107/2003/acpd-3-107-2003.pdf 107 134 2003-01-10 Chemical characteristics assigned to trajectory clusters during the MINOS campaign M. Traub H. Fischer M. de Reus R. Kormann J. Heland H. Ziereis H. Schlager R. Holzinger J. Williams C. Warneke J. de Gouw J. Lelieveld Max-Planck-Institute for Chemistry, Mainz, Germany Institute for Atmospheric Physics, DLR, Oberpfaffenhofen, Germany NOAA Aeronomy Laboratory, Boulder, Colorado, USA During the Mediterranean Intensive Oxidant Study (MINOS) in August 2001 a total of 14 measurement flights were performed with the DLR Falcon aircraft from Heraklion, Crete. One objective of this campaign was to investigate the role of long-range transport of pollutants into the Mediterranean area. An analysis of 5-day back trajectories indicates that in the lower troposphere (0–4 km) air masses originated from eastern and western Europe, in the mid-troposphere (4–8 km) from the Atlantic Ocean region and in the upper troposphere (8–14 km) from North Artlantic Ocean/North America  (NAONA) as well as South Asia. We allocated all back trajectories to clusters based on their ending height and source region. The mixing ratios of ozone, nitrogen oxide, total reactive oxidized nitrogen (NO_y), formaldehyde, methanol, acetonitrile, acetone, peroxyacetyl nitrate (PAN), carbon dioxide, carbon monoxide and methane measured along the flight tracks are examined in relation to the different cluster trajectories. In the lower troposphere the mean gas mixing ratios of the eastern Europe cluster trajectories were significantly higher than that from western Europe. Considering 2-day instead of 5-day trajectories the relative differences between the concentrations of these two clusters increased. In the upper troposphere relatively high concentrations of  O₃ and NO_y, combined with low CO of the NAONA trajectories indicate mixing with stratospheric air masses.