Aerosol optical properties in the southeastern United States in summer - Part 1: Hygroscopic growth

Details

• Journal Title:
  Atmospheric Chemistry and Physics
• Personal Author:
  Brock, Charles A. ; Wagner, Nicholas L. ; Anderson, Bruce E. ; Attwood, Alexis R. ; Beyersdorf, Andreas ; Campuzano-Jost, Pedro ; Carlton, Annmarie G. ; Day, Douglas A. ; Diskin, Glenn S. ; Gordon, Timothy D. ; Jimenez, Jose L. ; Lack, Daniel A. ; Liao, Jin ; Markovic, Milos Z. ; Middlebrook, Ann M. ; Ng, Nga L. ; Perring, Anne E. ; Richardson, Matthews S. ; Schwarz, Joshua P. ; Washenfelder, Rebecca A. ; Welti, Andre ; Xu, Lu ; Ziemba, Luke D. ; Murphy, Daniel M.
• NOAA Program & Office:
  OAR (Oceanic and Atmospheric Research) ; ESRL (Earth System Research Laboratory) ; CIRES (Cooperative Institute for Research in Environmental Sciences) ; CSL (Chemical Sciences Laboratory)
• Description:
  Aircraft observations of meteorological, trace gas, and aerosol properties were made during May-September 2013 in the southeastern United States (US) under fair-weather, afternoon conditions with well-defined planetary boundary layer structure. Optical extinction at 532aEuro-nm was directly measured at relative humidities (RHs) of aEuro-15, aEuro-70, and aEuro-90aEuro-% and compared with extinction calculated from measurements of aerosol composition and size distribution using the kappa-Kohler approximation for hygroscopic growth. The calculated enhancement in hydrated aerosol extinction with relative humidity, f(RH), calculated by this method agreed well with the observed f(RH) at aEuro-90aEuro-% RH. The dominance of organic aerosol, which comprised 65aEuro-+/- aEuro-10aEuro-% of particulate matter with aerodynamic diameter < aEuro-1aEuro-A mu m in the planetary boundary layer, resulted in relatively low f(RH) values of 1.43aEuro-+/- aEuro-0.67 at 70aEuro-% RH and 2.28aEuro-+/- aEuro-1.05 at 90aEuro-% RH. The subsaturated kappa-Kohler hygroscopicity parameter kappa for the organic fraction of the aerosol must have been < aEuro-0.10 to be consistent with 75aEuro-% of the observations within uncertainties, with a best estimate of kappa aEuro- = aEuro-0.05. This subsaturated kappa value for the organic aerosol in the southeastern US is broadly consistent with field studies in rural environments. A new, physically based, single-parameter representation was developed that better described f(RH) than did the widely used gamma power-law approximation.
• Source:
  Atmospheric Chemistry and Physics, 16(8), 4987-5007.
• DOI:
  https://doi.org/10.5194/acp-16-4987-2016
• Document Type:
  Journal Article
• Rights Information:
  CC BY
• Compliance:
  Submitted
• Main Document Checksum:
  urn:sha-512:1f2bcfad717010989ce89c85421b210601d8f891b736bf7bbbdd503a15d29cbdc16e8420d0ff7ebf95b57b29084879293519c3304481d5b009ae5ef0ab3eeff1
• Download URL:
  https://repository.library.noaa.gov/view/noaa/22103/noaa_22103_DS1.pdf
• File Type:
  [PDF - 10.08 MB ]