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Atmospheric Chemistry and Physics An interactive open-access journal of the European Geosciences Union
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.
Research article
08 May 2018
Review status
This discussion paper is a preprint. It is a manuscript under review for the journal Atmospheric Chemistry and Physics (ACP).
Characterization of aerosol growth events over Ellesmere Island during the summers of 2015 and 2016
Samantha Tremblay1, Jean-Christophe Picard1, Jill O. Bachelder1, Erik Lutsch2, Kimberly Strong2, Pierre Fogal2, W. Richard Leaitch3, Sangeeta Sharma3, Felicia Kolonjari3, Christopher J. Cox4,5, Rachel Y.-W. Chang6, and Patrick L. Hayes1 1Department of Chemistry, Université de Montréal, Montréal, Québec, Canada
2Department of Physics, University of Toronto, Toronto, Ontario, Canada
3Climate Research Division, Environment and Climate Change Canada, Toronto, Ontario, Canada
4Cooperative Institute for Research in Environmental Sciences (CIRES), Boulder, CO, USA
5NOAA Physical Sciences Division, Boulder, CO, USA
6Department of Physics and Atmospheric Science, Dalhousie University, Halifax, Nova Scotia, Canada
Abstract. The occurrence of frequent aerosol nucleation and growth events in the Arctic during summertime may impact the region’s climate through increasing the number of cloud condensation nuclei in the Arctic atmosphere. Measurements of aerosol size distributions and aerosol composition were taken during the summers of 2015 and 2016 at Eureka and Alert on Ellesmere Island in Nunavut, Canada. The corresponding results provide a better understanding of the frequency and spatial extent of these nucleation and growth events as well as of the composition and sources of aerosol mass during particle growth. These events are observed beginning in June with the melting of the sea ice rather than with polar sunrise, which strongly suggests emissions from marine sources are the primary cause of the events. Frequent particle nucleation followed by growth occurs throughout the summer. Correlated particle growths events at the two sites, separated by 480 km, indicate conditions existing over such large scales play a key role in determining the timing and the characteristics of the events.

In addition, aerosol mass spectrometry measurements are used to analyze the size-resolved chemical composition of aerosols during two selected growth events. It is found that particles with diameters smaller than 100 nm are predominately organic with only a small sulphate contribution. The oxidation of the organic fraction also changes with particle size with larger particles containing a greater fraction of organic acids relative to other non-acid oxygenates (e.g. alcohols or aldehydes). It is also observed that the relative amount of m / z 44 in the measured mass spectra increases during the growth events suggesting increases in organic acid concentrations in the particle phase.

The nucleation and growth events at Eureka are observed most often when the temperature inversion between the sea and the measurement site (at 610 m a.s.l.) is non-existent or weak allowing presumably fresh marine emissions to be mixed upward to the observatory altitude. While the nature of the gaseous precursors responsible for the growth events are poorly understood, oxidation of dimethyl sulphide alone to produce particle phase sulphate or methanesulphonic acid is not consistent with the measured aerosol composition, suggesting the importance of condensation of other gas phase organic compounds for particle growth.

Citation: Tremblay, S., Picard, J.-C., Bachelder, J. O., Lutsch, E., Strong, K., Fogal, P., Leaitch, W. R., Sharma, S., Kolonjari, F., Cox, C. J., Chang, R. Y.-W., and Hayes, P. L.: Characterization of aerosol growth events over Ellesmere Island during the summers of 2015 and 2016, Atmos. Chem. Phys. Discuss.,, in review, 2018.
Samantha Tremblay et al.
Samantha Tremblay et al.
Samantha Tremblay et al.


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Short summary
Atmospheric aerosols, tiny airborne particles, have an important impact on climate. However, a lack of understanding of the chemistry of aerosols is one of the largest contributors to uncertainty in predictions of climate change. Measurements of aerosols were carried out in Eureka, Canada in the Arctic to better understand what role aerosols play in this fragile environment. It is found that organic aerosols, possibly originating from marine emissions, are ubiquitous during summertime.
Atmospheric aerosols, tiny airborne particles, have an important impact on climate. However, a...