Arctic ship-based evidence of new particle formation events in the Chukchi and East Siberian Seas

11 pages, 7 figures.-- Supplementary data to this article can be found online at https://doi.org/10.1016/j.atmosenv.2019.11723.-- Data will be made available on requestArctic aerosol-climate interactions are controlled by multiple factors including sources, processes and removal mechanisms of particles. The Arctic is mostly ocean, surrounded by mostly land, and our understanding of Arctic aerosol processes is incomplete due to scarce measurements carried out in sea ice regions. In particular, it is currently not known if these particular regions are sources of aerosols of primary or secondary origin. We present new results from ship-based measurements illustrating that marine new particle production and growth events occur in open ocean and melting sea ice regions in the Chukchi and East Siberian Seas. We report two new particle formation events during which a recently formed nucleation mode (