| Title: | High concentration of ultrafine particles in the Amazon free troposphere produced by organic new particle formation |
| Author(s): | Zhao B; Shrivastava M; Donahue NM; Gordon H; Schervish M; Shilling JE; Zaveri RA; Wang J; Andreae MO; Zhao C; Gaudet B; Liu Y; Fan J; Fast JD; |
| Address: | "Atmospheric Sciences and Global Change Division, Pacific Northwest National Laboratory, Richland, WA 99352; bin.zhao@pnnl.gov Jerome.Fast@pnnl.gov. Atmospheric Sciences and Global Change Division, Pacific Northwest National Laboratory, Richland, WA 99352. Center for Atmospheric Particle Studies, Carnegie Mellon University, Pittsburgh, PA 15213. Department of Chemistry, Carnegie Mellon University, Pittsburgh, PA 15213. Department of Engineering and Public Policy, Carnegie Mellon University, Pittsburgh, PA 15213. Department of Chemical Engineering, Carnegie Mellon University, Pittsburgh, PA 15213. School of Earth and Environment, University of Leeds, Leeds LS2 9JT, United Kingdom. Center for Aerosol Science and Engineering, Department of Energy, Environmental and Chemical Engineering, Washington University in St. Louis, St. Louis, MO 63130. Multiphase Chemistry Department, Max Planck Institute for Chemistry, Mainz 55128, Germany. Scripps Institution of Oceanography, University of California San Diego, La Jolla, CA 92093. Department of Geology and Geophysics, King Saud University, Riyadh 11451, Saudi Arabia. School of Earth and Space Sciences, University of Science and Technology of China, 230026 Hefei, China. Chinese Academy of Sciences Center for Excellence in Comparative Planetology, University of Science and Technology of China, 230026 Hefei, China" |
| ISSN/ISBN: | 1091-6490 (Electronic) 0027-8424 (Print) 0027-8424 (Linking) |
| Abstract: | "The large concentrations of ultrafine particles consistently observed at high altitudes over the tropics represent one of the world's largest aerosol reservoirs, which may be providing a globally important source of cloud condensation nuclei. However, the sources and chemical processes contributing to the formation of these particles remain unclear. Here we investigate new particle formation (NPF) mechanisms in the Amazon free troposphere by integrating insights from laboratory measurements, chemical transport modeling, and field measurements. To account for organic NPF, we develop a comprehensive model representation of the temperature-dependent formation chemistry and thermodynamics of extremely low volatility organic compounds as well as their roles in NPF processes. We find that pure-organic NPF driven by natural biogenic emissions dominates in the uppermost troposphere above 13 km and accounts for 65 to 83% of the column total NPF rate under relatively pristine conditions, while ternary NPF involving organics and sulfuric acid dominates between 8 and 13 km. The large organic NPF rates at high altitudes mainly result from decreased volatility of organics and increased NPF efficiency at low temperatures, somewhat counterbalanced by a reduced chemical formation rate of extremely low volatility organic compounds. These findings imply a key role of naturally occurring organic NPF in high-altitude preindustrial environments and will help better quantify anthropogenic aerosol forcing from preindustrial times to the present day" |
| Keywords: | Amazon aerosol extremely low volatility organic compounds new particle formation troposphere; |
| Notes: | "PubMed-not-MEDLINEZhao, Bin Shrivastava, Manish Donahue, Neil M Gordon, Hamish Schervish, Meredith Shilling, John E Zaveri, Rahul A Wang, Jian Andreae, Meinrat O Zhao, Chun Gaudet, Brian Liu, Ying Fan, Jiwen Fast, Jerome D eng 80NSSC19K0949/ImNASA/Intramural NASA/ Research Support, Non-U.S. Gov't Research Support, U.S. Gov't, Non-P.H.S. 2020/09/30 Proc Natl Acad Sci U S A. 2020 Oct 13; 117(41):25344-25351. doi: 10.1073/pnas.2006716117. Epub 2020 Sep 28" |
