Submicron Organic Aerosol Types in the Summertime Arctic:Mixing State, Geographic Distribution, and Drivers

• Published in: Journal of Geophysical Research: Atmospheres
• Main Authors: Su, Bojiang, Zhang, Guohua, Song, Congbo, Liang, Yue, Wang, Longqun, Li, Lei, Zhou, Zhen, Yan, Jinpei, Wang, Xinming, Bi, Xinhui
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2024
• Subjects: driver; geographic distribution; individual organic aerosol particles; machine learning; mixing state; summertime high Arctic; Arctic; Chukchi Sea; Svalbard; Chukchi; Iceland; Sea ice
• Online Access: https://research.manchester.ac.uk/en/publications/63ff215e-1788-4959-b940-93ee0d1a1b1b; https://doi.org/10.1029/2024JD041061; http://www.scopus.com/inward/record.url?scp=85203401451&partnerID=8YFLogxK

During the 2017 summertime Arctic cruise observation campaigns, we measured over 290,000 individual submicron particles and clustered them into two inorganic classes (dominated by sea salt, accounting for 38.6% by number fraction) and five organic classes (dominated by natural and anthropogenic organics, 61.4%), presenting a distinct difference in geographic distribution. In the high Arctic and marginal ice zone (81.1–84.6°N) compared with the low Arctic (Chukchi Sea, Svalbard, and Iceland, <80°N), ocean-derived organic aerosols were more prevalent (73.6% vs. 37.1%). Specifically, we found sharp contrasts in the geographic distributions of OC-Ca (organics internally mixed with calcium, 29.0% vs. 9.4%) and OC-S (organics internally mixed with sulfate, 3.2% vs. 21.4%). Utilizing an explainable machine learning technique, we inferred that OC-Ca was driven by wind-blown sea ice and/or sea ice floes and/or bubble bursting within sea ice leads under low wind speed conditions in the high Arctic, while OC-S tended to associate with elemental carbon, sulfate, and higher temperatures, potentially originating from combustion emissions at low latitude regions.