0000000000417222
AUTHOR
Stéphane J. Gallavardin
Penetration efficiency of nanometer-sized aerosol particles in tubes under turbulent flow conditions
Abstract In order to quantify losses of nanometer-sized particles in turbulent flows through tubes, their penetration efficiencies were measured as a function of the particle size, Stokes number and Reynolds number. The penetration efficiency of tungsten oxide and ammonium nitrate particles with diameters between 3 and 17 nm was investigated in turbulent flow conditions with Reynolds numbers (Re) extending from 4500 to 10,500. The measured penetration efficiencies in straight tubes were found to deviate from the empirical correlation of Lee and Gieseke (1994) . In contrast, the empirical equation of Fan and Ahmadi (1993) agrees better with our experimental results, also in comparison with t…
Inadvertent climate modification due to anthropogenic lead
Atmospheric particles are thought to initiate the majority of terrestrial precipitation. Field-based measurements of ice-crystal residues, together with controlled environment experiments on artificial clouds, suggest that anthropogenic lead-containing particles are among the most efficient ice-forming substances in the atmosphere.
The ion trap aerosol mass spectrometer: improved design, first field deployment, and the capability of differentiating organic compound classes via MS–MS
Abstract. Further development and optimisation of a previously described ion trap aerosol mass spectrometer (IT-AMS) are presented, which resulted in more reproducible and robust operation and allowed for the instrument’s first field deployment. Results from this 11-day long measurement indicate that the instrument is capable of providing quantitative information on organics, nitrate, and sulphate mass concentrations with reasonable detection limits (0.5–1.4 µg m−3 for 1 h averages), and that results obtained with the IT-AMS can directly be related to those from Aerodyne aerosol mass spectrometers. The capability of the IT-AMS to elucidate the structure of fragment ions is demonstrated via …
Deactivation of ice nuclei due to atmospherically relevant surface coatings
The ice nucleation characteristics of Arizona test dust (ATD) and illite clay, surrogates for atmospheric ice nuclei, have been determined at the Aerosol Interactions and Dynamics in the Atmosphere (AIDA) chamber located at the Research Center Karlsruhe in Germany. The objective of this research was to determine the effect of sulfuric acid and ammonium sulfate coatings on the ability of these mineral dust surrogates to nucleate ice in an environment where particles realistically compete for water vapor. Coated ATD particles required higher saturations at all temperatures considered, from −20 to −45 ◦ C, than did identical uncoated particles. Freezing of coated particles often required satur…