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Title: Ice cloud formation potential by free tropospheric particles from long-range transport over the Northern Atlantic Ocean

Long-range transported free tropospheric particles can play a significant role on heterogeneous ice nucleation. Using optical and electron microscopy we examine the physicochemical characteristics of ice nucleating particles (INPs). Particles were collected on substrates from the free troposphere at the remote Pico Mountain Observatory in the Azores Islands, after long-range transport and aging over the Atlantic Ocean. We investigate four specific events to study the ice formation potential by the collected particles with different ages and transport patterns. We use single-particle analysis, as well as bulk analysis to characterize particle populations. Both analyses show substantial differences in particle composition between samples from the four events; in addition, single-particle microscopy analysis indicates that most particles are coated by organic material. The identified INPs contained mixtures of dust, aged sea salt and soot, and organic material acquired either at the source or during transport. The temperature and relative humidity ( RH) at which ice formed, varied only by 5% between samples, despite differences in particle composition, sources, and transport patterns. We hypothesize that this small variation in the onset RH may be due to the coating material on the particles. Finally, this study underscores and motivates the need to further investigate howmore » long-range transported and atmospherically aged free tropospheric particles impact ice cloud formation.« less
ORCiD logo [1] ; ORCiD logo [2] ; ORCiD logo [3] ; ORCiD logo [3] ; ORCiD logo [4] ;  [3] ;  [5] ; ORCiD logo [6] ; ORCiD logo [3] ; ORCiD logo [3] ; ORCiD logo [7]
  1. Michigan Technological Univ., Houghton, MI (United States); Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
  2. Stony Brook Univ., Stony Brook, NY (United States); Paul Scherrer Inst. (PSI), Villigen (Switzerland)
  3. Michigan Technological Univ., Houghton, MI (United States)
  4. Michigan Technological Univ., Houghton, MI (United States); Univ. of Rijeka, Rijeka (Croatia)
  5. Michigan Technological Univ., Houghton, MI (United States); U.S. Environmental Protection Agency, RTP, NC (United States)
  6. Instituto de Investigacao em Vulcanologia e Avaliacao de Riscos da Univ. dos Acores, Acores (Portugal)
  7. Stony Brook Univ., Stony Brook, NY (United States)
Publication Date:
Grant/Contract Number:
SC0016370; SC0008613; SC0006941
Accepted Manuscript
Journal Name:
Journal of Geophysical Research: Atmospheres
Additional Journal Information:
Journal Volume: 122; Journal Issue: 5; Journal ID: ISSN 2169-897X
American Geophysical Union
Research Org:
Stony Brook Univ., Stony Brook, NY (United States)
Sponsoring Org:
USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC-23)
Country of Publication:
United States
OSTI Identifier:
Alternate Identifier(s):
OSTI ID: 1377929