Rapid, size-resolved aerosol hygroscopic growth measurements: Differential aerosol sizing and hygroscopicity spectrometer probe (DASH-SP)

Armin Sorooshian, Scott Hersey, Fred J. Brechtel, Andrew Corless, Richard C. Flagan, John H. Seinfeld

Research output: Contribution to journalArticle

46 Scopus citations

Abstract

We report on a new instrument developed to perform rapid, size-resolved aerosol hygroscopicity measurements. The differential aerosol sizing and hygroscopicity spectrometer probe (DASH-SP) employs differential mobility analysis in-concert with multiple humidification and optical sizing steps to determine dry optical size and hygroscopic growth factors for size-selected aerosols simultaneously at three elevated relative humidities. The DASH-SP has been designed especially for aircraft-based measurements, with time resolution as short as a few seconds. The minimum particle diameter detected with 50% efficiency in the optical particle counters (OPCs) is 135 ± 8 nm, while the maximum detectable particle diameter is in excess of 1 μm. An iterative data processing algorithm quantifies growth factors and "effective" refractive indices for humidified particles using an empirically derived three-dimensional surface (OPC pulse height-refractive index-particle size), based on a calculated value of the "effective" dry particle refractive index. Excellent agreement is obtained between DASH-SP laboratory data and thermodynamic model predictions for growth factor dependence on relative humidity for various inorganic salts. Growth factor data are also presented for several organic acids. Oxalic, malonic, glutaric, and glyoxylic acids grow gradually with increasing relative humidity up to 94%, while succinic and adipic acids show no growth. Airborne measurements of hygroscopic growth factors of ship exhaust aerosol during the 2007 Marine Stratus/Stratocumulus Experiment (MASE II) field campaign off the central coast of California are presented as the first report of the aircraft integration of the DASH-SP.

Original languageEnglish (US)
Pages (from-to)445-464
Number of pages20
JournalAerosol Science and Technology
Volume42
Issue number6
DOIs
StatePublished - Jun 1 2008
Externally publishedYes

ASJC Scopus subject areas

  • Environmental Chemistry
  • Materials Science(all)
  • Pollution

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