Comparisons of aerosol properties measured by impactors and light scattering from individual particles: Refractive index, number and volume concentrations, and size distributions

Jennifer L. Hand, Sonia M. Kreidenweis, Nathan Kreisberg, Susanne Hering, Mark Stolzenburg, William Dick, Peter H. McMurry

Research output: Contribution to journalArticlepeer-review

22 Scopus citations

Abstract

The southeastern aerosol and visibility study (SEAVS) was conducted in Great Smoky Mountains National Park in summer 1995 to investigate variations in ambient aerosol size distributions and their effect on visibility. In this paper, we compare dry aerosol size distribution parameters from a MOUDI impactor and two different optical particle counters (OPCs). Size distributions from the various instruments are expressed in a common measure of size, specifically, optical and aerodynamic diameters are converted to a dry, geometric diameter basis. Comparisons of the real part of particle refractive index obtained directly from light scattering measurements and inferred from aerosol composition measurements are also shown. Real refractive indices from direct measurements and those computed from measured fine aerosol chemical composition were generally within ±0.02. Maximum differences in estimated accumulation mode integrated volume concentrations from all instruments were within ∼22%. Accumulation mode integrated number concentrations and geometric standard deviations from the two OPCs agreed within ∼30% and ∼3%, respectively. Differences between MOUDI- and OPC-derived accumulation mode number concentrations and geometric standard deviations were ∼20% and ∼8%, respectively. The average geometric volume mean diameters derived from the three instruments agreed within 15% or less. The volume median diameters obtained by fitting the CSU number concentration data to a lognormal function were typically the smallest. We show that these discrepancies can be related to the differences and biases in the measurement and data analysis techniques.

Original languageEnglish (US)
Pages (from-to)1853-1861
Number of pages9
JournalAtmospheric Environment
Volume36
Issue number11
DOIs
StatePublished - Apr 17 2002

Keywords

  • Aerosol monitoring
  • Intercomparison
  • Particle size distributions
  • Refractive index
  • Southeastern US

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