An aircraft-based case study of new particle formation and growth in the summertime Arctic

Monday, 14 December 2015
Poster Hall (Moscone South)
Jonathan Abbatt1, Megan D Willis2, Julia Burkart1, Heiko Bozem3, Franziska Koellner3, Johannes Schneider4, Peter Michael Hoor3, Andreas Bodo Herber5 and Warren Richard Leaitch6, (1)University of Toronto, Chemistry, Toronto, ON, Canada, (2)University of Toronto, Toronto, ON, Canada, (3)Johannes Gutenberg University of Mainz, Institute for Atmospheric Physics, Mainz, Germany, (4)Max Planck Institute for Chemistry, Particle Chemistry Department, Mainz, Germany, (5)Alfred Wegener Institute Helmholtz-Center for Polar and Marine Research Bremerhaven, Bremerhaven, Germany, (6)Environment Canada, Toronto, ON, Canada
Motivated by the changing climate of the Arctic and decreasing summer sea-ice extent, we aim to better understand how atmospheric composition will impact, or be impacted by, climate and environmental change in this region. Much attention has been paid to springtime Arctic aerosol owing to significant anthropogenic influence on this remote environment, but the cleaner, more locally influenced summertime Arctic is not well characterized.

We present results of vertically resolved, particle number, aerosol size distributions, submicron aerosol composition from an aerosol mass spectrometer (AMS), and cloud condensation nuclei (CCN) concentrations from the NETCARE 2014 Polar 6 aircraft campaign. The campaign was based in the high Arctic, at Resolute Bay, Nunavut, Canada (74°N, 94°W), allowing measurements from 60 to 2900 meters over ice, open water and near the ice-edge.

The focus of this case study is a new particle formation and growth event observed at the eastern end of Lancaster Sound (74°N, 81°W) on July 12, 2014 under clear sky conditions. During this flight Polar 6 travelled to the end of Lancaster Sound at 2900 m and subsequently descended to 60-70 m above the surface heading due west, with winds from the west. At the lowest altitude we observed a significant increase in particles > 4 nm, between 20 – 100 nm, and > 100 nm, indicating the presence of small particles between 4 – 20 nm and growth to larger sizes. In addition, CCN concentrations were enhanced up to ~ 200/cm3 from background levels of ≤ 100/cm3. Concurrently, the AMS indicated enhanced levels of methane sulfonic acid (MSA) and marine-like organic aerosol (OA) correlated in time with the presence of larger particles, as well as an iodide signal which correlated with the presence of small particles. These observations suggest that iodine oxides could be one contributor to particle formation, and that marine-like OA and MSA could contribute to particle growth in the summertime Arctic.