1Laboratory for Atmospheric Chemistry, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
2School of Earth, Atmospheric and Environmental Sciences, University of Manchester, M60 1QD, UK
3Leibniz-Institute for Tropospheric Research, 04318 Leipzig, Germany
4Empa, Laboratory for Air Pollution/Environmental Technology, 8600 Dübendorf, Switzerland
5Federal Office of Meteorology and Climatology, MeteoSwiss, Aerological Station, 1530 Payerne, Switzerland
6Institute for Atmospheric Physics, German Aerospace Centre, 82234 Wessling, Germany
*now at: Energy research Centre of the Netherlands ECN, P.O. Box 1, 1755 ZG Petten, The Netherlands
Abstract. The chemical composition of submicron (fine mode) and supermicron (coarse mode) aerosol particles has been investigated since 1999 within the GAW aerosol monitoring program at the high alpine research station Jungfraujoch (3580 m a.s.l., Switzerland). Clear seasonality was observed for all major components in the last 9 years with low concentrations in winter (predominantly free tropospheric aerosol) and higher concentrations in summer (enhanced vertical transport of boundary layer pollutants). In addition, mass closure was attempted during intensive experiments in March 2004, February–March 2005 and August 2005. Ionic, carbonaceous and refractory components of the aerosol were quantified as well as the PM1 and coarse mode total aerosol mass concentrations. A relatively low conversion factor of 1.8 for organic carbon (OC) to particulate organic matter (OM) in winter (February–March 2005) was found. Organics, sulfate, ammonium, and nitrate were the major identified components of the fine aerosol fraction, while calcium and nitrate were the two major measured components in the coarse mode. The aerosol mass concentrations for fine and coarse mode aerosol during the intensive campaigns were not typical of the long term seasonality due largely to dynamical differences. Average fine and coarse mode concentrations during the intensive field campaigns were 1.7 μg m−3 and 2.4 μg m−3 in winter and 2.5 μg m−3 and 2.0 μg m−3 in summer, respectively. The mass balance of aerosols showed higher contributions of calcium and nitrate in the coarse mode during Saharan dust events (SDE) than without SDE.