Airborne characterization of subsaturated aerosol hygroscopicity and dry refractive index from the surface to 6.5km during the SEAC4RS campaign

Taylor Shingler, Ewan Crosbie, Amber Ortega, Manabu Shiraiwa, Andreas Zuend, Andreas Beyersdorf, Luke Ziemba, Bruce Anderson, Lee Thornhill, Anne E. Perring, Joshua P. Schwarz, Pedro Campazano-Jost, Douglas A. Day, Jose L. Jimenez, Johnathan W. Hair, Tomas Mikoviny, Armin Wisthaler, Armin Sorooshian

Research output: Contribution to journalArticlepeer-review

53 Scopus citations


In situ aerosol particle measurements were conducted during 21 NASA DC-8 flights in the Studies of Emissions and Atmospheric Composition, Clouds, and Climate Coupling by Regional Surveys field campaign over the United States, Canada, Pacific Ocean, and Gulf ofMexico. For the first time, this study reports rapid, size-resolved hygroscopic growth and real refractive index (RI at 532nm) data between the surface and upper troposphere in a variety of air masses including wildfires, agricultural fires, biogenic, marine, and urban outflow. The Differential Aerosol Sizing and Hygroscopicity Spectrometer Probe (DASH-SP) quantified size-resolved diameter growth factors (GF =Dp,wet/Dp,dry) that are used to infer the hygroscopicity parameter κ. Thermokinetic simulations were conducted to estimate the impact of partial particle volatilization within the DASH-SP across a range of sampling conditions. Analyses of GF and RI data as a function of air mass origin, dry size, and altitude are reported, in addition to κ values for the inorganic and organic fractions of aerosol. Average RI values are found to be fairly constant (1.52–1.54) for all air mass categories. An algorithm is used to compare size-resolved DASH-SP GF with bulk scattering f(RH= 80%) data obtained froma pair of nephelometers, and the results show that the two can only be reconciled if GF is assumed to decrease with increasing dry size above 400nm (i.e., beyond the upper bound of DASH-SP measurements). Individual case studies illustrate variations of hygroscopicity as a function of dry size, environmental conditions, altitude, and composition.

Original languageEnglish (US)
Pages (from-to)4188-4210
Number of pages23
JournalJournal of geophysical research
Issue number8
StatePublished - 2016

ASJC Scopus subject areas

  • Geophysics
  • Oceanography
  • Forestry
  • Aquatic Science
  • Ecology
  • Water Science and Technology
  • Soil Science
  • Geochemistry and Petrology
  • Earth-Surface Processes
  • Atmospheric Science
  • Space and Planetary Science
  • Earth and Planetary Sciences (miscellaneous)
  • Palaeontology


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