Characterization of aerosol growth events over Ellesmere Island during the summers of 2015 and 2016
<p>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 t...
| Main Authors: | , , , , , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2019-04-01
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| Series: | Atmospheric Chemistry and Physics |
| Online Access: | https://www.atmos-chem-phys.net/19/5589/2019/acp-19-5589-2019.pdf |
| Summary: | <p>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. These results provide a better understanding of the frequency and
spatial extent of elevated Aitken mode aerosol concentrations as well as of
the composition and sources of aerosol mass during particle growth. Frequent
appearances of small particles followed by growth occurred throughout the
summer. These particle growth events were observed beginning in June with the
melting of the sea ice rather than with the polar sunrise, which strongly
suggests that influence from the marine boundary layer was the primary cause
of the events. Correlated particle growth events at the two sites, separated
by 480 km, indicate conditions existing over large scales play a key role in
determining the timing and the characteristics of the events.</p>
<p>In addition, aerosol mass spectrometry measurements were used to analyze the
size-resolved chemical composition of aerosols during two selected growth
events. It was found that particles with diameters between 50 and 80 nm
(physical diameter) during these growth events were predominately organic
with only a small sulfate contribution. The oxidation of the organics also
changed with particle size, with the fraction of organic acids increasing
with diameter from 80 to 400 nm.</p>
<p>The growth events at Eureka were observed most often when the temperature
inversion between the sea and the measurement site (at 610 m a.s.l.) was
non-existent or weak, presumably creating conditions with low aerosol
condensation sink and allowing fresh marine emissions to be mixed upward to
the observatory's altitude. While the nature of the gaseous precursors
responsible for the growth events is still poorly understood, oxidation of
dimethyl sulfide alone to produce particle-phase sulfate or
methanesulfonic acid was inconsistent with the measured aerosol composition,
suggesting the importance of other gas-phase organic compounds condensing for
particle growth.</p> |
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| ISSN: | 1680-7316 1680-7324 |