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

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)

PCASP - Passive Cavity Aerosol Spectrometer, r >  m

FSSP - Forward Scattering Spectrometer Probe, r >  m

MASP - Multi-angle Aerosol Scattering Probe, r >  m

Nephelometer - aerosol scattering, hemispheric backscatter

Aethalometer - aerosol absorption

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

Aerodyne Aerosol Mass Spectrometer

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: ,000 nm –concentrations: cm -3 –shape droplets to chain aggregates –compositions - large fraction of the periodic table

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

Methoden2.pdf Acknowledging some of the material sources TSI Inc web site

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 Christoph Weisser, Max-Planck-Institut für Kernphysik, Heidelberg Aerodynamic Lens - Focussing Principle