Abstract
Abstract One year of aerosol particle observations from Alert, Nunavut shows that new particle formation (NPF) is common during clean periods of the summertime Arctic associated with attendant low condensation sinks and with the presence of methane sulfonic acid (MSA), a product of the atmospheric oxidation of dimethyl sulfide (DMS). The clean aerosol time periods, defined using the distribution of refractory black carbon number concentrations, increase in frequency from June through August as the anthropogenic influence dwindles. During the clean periods, the number concentrations of particles that can act as cloud condensation nuclei (CCN) increase from June through August suggesting that DMS, and possibly other oceanic organic precursors, exert significant control on the Arctic summertime submicron aerosol, a proposition supported by simulations from the GEOS-Chem-TOMAS global chemical transport model with particle microphysics. The CCN increase for the clean periods across the summer is estimated to be able to increase cloud droplet number concentrations (CDNC) by 23–44 cm-3, comparable to the mean CDNC increase needed to yield the current global cloud albedo forcing from industrial aerosols. These results suggest that DMS may contribute significantly to modification of the Arctic summer shortwave cloud albedo, and they offer a reference for future changes in the Arctic summer aerosol.
Highlights
The Arctic is warming more rapidly than other regions of the world (ACIA, 2005), and a significant increase in anthropogenic activities in the Arctic is expected by mid-century if not before (Smith and Stephenson, 2013) that will further contribute to the changing Arctic climate
One year of aerosol particle observations from Alert, Nunavut shows that new particle formation (NPF) is common during clean periods of the summertime Arctic associated with attendant low condensation sinks and with the presence of methane sulfonic acid (MSA), a product of the atmospheric oxidation of dimethyl sulfide (DMS)
The number concentrations of particles that can act as cloud condensation nuclei (CCN) increase from June through August suggesting that DMS, and possibly other oceanic organic precursors, exert significant control on the Arctic summertime submicron aerosol, a proposition supported by simulations from the GEOS-Chem-TwO-Moment Aerosol Sectional (TOMAS) global chemical transport model with particle microphysics
Summary
The Arctic is warming more rapidly than other regions of the world (ACIA, 2005), and a significant increase in anthropogenic activities in the Arctic is expected by mid-century if not before (Smith and Stephenson, 2013) that will further contribute to the changing Arctic climate. DMS is oxidized primarily to methane sulfonic acid (MSA) and sulfur dioxide (SO2), and the SO2 can be further oxidized to H2SO4 that can form new particles. MSA has some possibility of contributing to new particle formation (NPF), but its ability to nucleate is much lower than that of H2SO4 due to a higher saturation vapor pressure.
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