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Atmospheric Particles Size range: 0.003 to 50  m, 0.003  m particle contains ~1000 molecules

Atmospheric Particles Size range: 0.003 to 50  m, 0.003  m particle contains ~1000 molecules Concentration ranges: 10 -5 - 10 5 cm -3 = 10 - 10 11 m -3 Sources: combustion, organic emissions, volcanoes, earth’s surface, gas to particle conversions, …

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Atmospheric Particles Size range: 0.003 to 50  m, 0.003  m particle contains ~1000 molecules

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  1. Atmospheric Particles • Size range: 0.003 to 50 m, 0.003 m particle contains ~1000 molecules • Concentration ranges: 10-5 - 105 cm-3 = 10 - 1011 m-3 • Sources: combustion, organic emissions, volcanoes, earth’s surface, gas to particle conversions, … • Mass concentrations: 1 - 100 g m-3 (density of air 1 kg m-3) ppbm • Composition: sulfates, nitrates, ammonium, organics, carbon, crustal material, silicates, water, … • Removal: sedimentation, cloud processes, evaporation.

  2. Complete characterization of atmospheric aerosol requires time and space resolved measurements of aerosol: • number • size (geometric, optical, aerodynamic) • surface area • volume • mass • composition • optical properties (scattering + absorption = extinction) • shape (droplets to chain aggregates) • phase • charge • nucleating characteristics (nucleation of water, ice, nitric acid hydrates)

  3. PCASP -Passive Cavity Aerosol Spectrometer, r > 0.05 - 1.5 m

  4. FSSP - Forward Scattering Spectrometer Probe, r > 0.2 - 15.0 m

  5. MASP - Multi-angle Aerosol Scattering Probe, r > 0.2 - 10.0 m

  6. Nephelometer - aerosol scattering, hemispheric backscatter

  7. Aethalometer - aerosol absorption

  8. Aerosol Composition Mass Spectrometer (ACMS) Christoph Weisser, Max-Planck-Institut für Kernphysik, Heidelberg Magnetic Electron 50C

  9. Aerodyne Aerosol Mass Spectrometer

  10. The Facts • Atmospheric aerosol have a global impact on the atmosphere far exceeding their mass concentration. These impacts include pivotal roles in the hydrologic, radiative, and chemical balance of the atmosphere. • Atmospheric aerosol are difficult to measure, and instrument selection depends heavily on measurement goals and ranges of interest. • Measurement errors/variations are inherently large due to small sample sizes and large geophysical variations. • Measurement quality depends heavily on frequent and careful instrument calibration and characterization. • A complete characterization of atmospheric aerosol populations is only addressable with a suite of instruments. • Atmospheric aerosol ranges: • size: 1 - 10,000 nm • concentrations: 10-4 - 104 cm-3 • shape droplets to chain aggregates • compositions - large fraction of the periodic table

  11. The Challenges • Provide a climatology of tropospheric aerosol which reduces uncertainties in our understanding of earth’s radiation budget, particularly over continents. • Address questions related to the variation of single scatter albedo from hemisphere to hemisphere, maritime - continental, urban - rural • Refine our understanding of the processes of water, ice, and hydrate nucleation, and characterize the populations of cloud condensation nuclei, ice nuclei, and hydrate nuclei. • Establish proper extrapolations: • from surface aerosol measurements to atmospheric aerosol profiles • from local to global measurements • from global satellite measurements to global geophysical parameters

  12. Acknowledging some of the material sources TSI Inc web site http://www.iac.ethz.ch/staff/krieger/pdf/SpektroskopischeMethoden2.pdf

  13. Aerodynamic Lens - Focussing Principle thin plate orifices aerosols aerosol beam exit inlet Christoph Weisser, Max-Planck-Institut für Kernphysik, Heidelberg • optimized to focus particles between 0.1 and 2 µm • transmission better than 90% at 40 – 70 mbar, decreases towards larger paricles • transition time 30 ms, composition changes negligible

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