New particle formation characteristics in the Arctic (Zeppelin, Svalbard)

Continuous measurement of atmospheric nanoparticles down to 3 nm was conducted in the Arctic (Zeppelin) from Oct 2016 to Dec 2018. The measured size distributions of particles from 3 nm to 60 nm were classified into distinct clusters with mode diameters of 10 nm (cluster 1), 20 nm (cluster 2), 30 nm (cluster 3), and 50 nm (cluster 4). Cluster 1 includes newly formed particles with high population which was often observed in summer season. A significant amount of nanoparticles down to 3 nm often appeared during new particle formation (NPF), suggesting that the NPF happened near the site rather than being transported from other regions after growth. The average NPF occurrence frequency per year was found to be 28%. The particle formation rate (J_3-7) for particles in 3 nm to 7 nm was 0.044 cm^-3 s^-1 on average, ranging from 0.001 to 0.714 cm^-3 s^-1. The average growth rate (GR_3-25) was around 2.62 nm h^-1. Even though the NPF occurrence frequency in the Arctic was comparable to other areas (highly or moderately polluted areas), the intensity of NPF events (e.g. J_3-7 and GR_3-25) was much smaller than other continental areas. The increase of nanoparticles occurred more frequently when the air mass passed over the south and southwest ocean region, and concentration of NH₃ increased in the NPF event days compared to non-event days, suggesting that that the marine biogenic and animal sources played important roles in the NPF. The NPF occurrence criteria previously developed was also applicable for the NPF in the Arctic.