Journal cover Journal topic
Atmospheric Chemistry and Physics An interactive open-access journal of the European Geosciences Union
Atmos. Chem. Phys., 17, 5515-5535, 2017
http://www.atmos-chem-phys.net/17/5515/2017/
doi:10.5194/acp-17-5515-2017
© Author(s) 2017. This work is distributed
under the Creative Commons Attribution 3.0 License.
Research article
02 May 2017
Summertime observations of elevated levels of ultrafine particles in the high Arctic marine boundary layer
Julia Burkart1, Megan D. Willis1, Heiko Bozem2, Jennie L. Thomas3, Kathy Law3, Peter Hoor2, Amir A. Aliabadi4, Franziska Köllner5, Johannes Schneider5, Andreas Herber6, Jonathan P. D. Abbatt1, and W. Richard Leaitch7 1Department of Chemistry, University of Toronto, Toronto, Canada
2Institute of Atmospheric Physics, Johannes Gutenberg-University, Mainz, Germany
3LATMOS/IPSL, UPMC Univ. Paris 06 Sorbonne Universités, UVSQ, CNRS, Paris, France
4Environmental Engineering Program, University of Guelph, Guelph, Canada
5Particle Chemistry Department, Max Planck Institute for Chemistry, Mainz, Germany
6Alfred Wegener Institute, Helmholtz Center for Polar and Marine Research, Bremerhaven, Germany
7Environment and Climate Change Canada, Toronto, Ontario, Canada
Abstract. Motivated by increasing levels of open ocean in the Arctic summer and the lack of prior altitude-resolved studies, extensive aerosol measurements were made during 11 flights of the NETCARE July 2014 airborne campaign from Resolute Bay, Nunavut. Flights included vertical profiles (60 to 3000 m above ground level) over open ocean, fast ice, and boundary layer clouds and fogs. A general conclusion, from observations of particle numbers between 5 and 20 nm in diameter (N5 − 20), is that ultrafine particle formation occurs readily in the Canadian high Arctic marine boundary layer, especially just above ocean and clouds, reaching values of a few thousand particles cm−3. By contrast, ultrafine particle concentrations are much lower in the free troposphere. Elevated levels of larger particles (for example, from 20 to 40 nm in size, N20 − 40) are sometimes associated with high N5 − 20, especially over low clouds, suggestive of aerosol growth. The number densities of particles greater than 40 nm in diameter (N >  40) are relatively depleted at the lowest altitudes, indicative of depositional processes that will lower the condensation sink and promote new particle formation. The number of cloud condensation nuclei (CCN; measured at 0.6 % supersaturation) are positively correlated with the numbers of small particles (down to roughly 30 nm), indicating that some fraction of these newly formed particles are capable of being involved in cloud activation. Given that the summertime marine Arctic is a biologically active region, it is important to better establish the links between emissions from the ocean and the formation and growth of ultrafine particles within this rapidly changing environment.

Citation: Burkart, J., Willis, M. D., Bozem, H., Thomas, J. L., Law, K., Hoor, P., Aliabadi, A. A., Köllner, F., Schneider, J., Herber, A., Abbatt, J. P. D., and Leaitch, W. R.: Summertime observations of elevated levels of ultrafine particles in the high Arctic marine boundary layer, Atmos. Chem. Phys., 17, 5515-5535, doi:10.5194/acp-17-5515-2017, 2017.
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Short summary
Our aircraft study for the first time systematically investigates aerosol size distributions, including ultrafine particles (5–20 nm in diameter), in the Arctic summertime atmosphere. We find that ultrafine particles occur very frequently in the boundary layer and not aloft, suggesting a surface source of these particles. Understanding aerosol properties and sources is crucial to predict climate and especially important in the Arctic as this region responds extremely fast to climate change.
Our aircraft study for the first time systematically investigates aerosol size distributions,...
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