HR: 0800h
AN: A41C-03    [Abstracts]
TI: Transmission Electron Microscopy Analysis of Submicronic Aerosol Particles Sampled at Jungfraujoch, Switzerland (CLACE-4)
AU: * Grobéty, B
EM: bernard.grobety@unifr.ch
AF: Dep. of Geosciences, Univ. of Fribourg, Perolles, Fribourg, 1700, Switzerland
AU: * Grobéty, B
EM: bernard.grobety@unifr.ch
AF: FRIMAT Center of Nanomaterials, Perolles, Fribourg, 1700, Switzerland
AU: Lorenzo, R
EM: Ronny.Lorenzo@empa.ch
AF: EMPA, Material Science and Technology, Ueberlandstrasse 129, Dübendorf, 8600, Switzerland
AB: Submicronic aerosol particles were collected in two sampling campaigns during CLACE-4 and -5 ("the Cloud and Aerosol Characterisation Experiment in the Free Troposphere") at the high alpine research station on top of Jungfraujoch (altitude: 3580 m.a.s.l.). The particles were deposited directly on transmission electron microscopy (TEM) grids placed in a home-made, calibrated thermophoretic sampling device. The samples were taken during periods of clear skies and temperatures below 0°C. Average sampling time was two days. The primary state of the particles was either solid, mixed solid-liquid or completely liquid. EDS spectra of solid particles without visible traces of a liquid coating contain only carbon and oxygen peaks. Mixed solid-fluid particles, however, have either carbon (C), mixed carbon-silicate (CS) or silicate (S) (probably SiO2) nuclei. The condensates remaining after evaporation of the liquid components contain sulfate (sulfur and oxygen peaks in EDS spectra), but no nitrate was found. The fraction > 500 nm is dominated by C and CS particles, the silicate particles have a narrow size distribution around 100 nm and contain, if at all, only faint sulfur peaks in their EDS spectra. The results are qualitatively consistent with analyses of samples collected during the same campaign (Weinbruch et al., 2005), but during mixed cloud events. There seem to be, however a differrence in the amount of particles with sulfate coatings, which is higher for samples taken under clear sky conditions. Weinbruch, S., Ebert, S., Worringen, A., and Brenker (2005), Identification of the ice forming fraction of the atmospheric aerosol in mixed-phase clouds by environmental scanning electron microscopy. Activity report 2005, International Foundation HFSJG.
DE: 0300 ATMOSPHERIC COMPOSITION AND STRUCTURE
DE: 0305 Aerosols and particles (0345, 4801, 4906)
DE: 0394 Instruments and techniques
SC: Atmospheric Sciences [A]
MN: 2007 Joint Assembly