Influence of transport and ocean ice extent on biogenic aerosol sulfur in the Arctic atmosphere

Abstract

[1] The recent decline in sea ice cover in the Arctic Ocean could affect the regional radiative forcing via changes in sea ice-atmosphere exchange of dimethyl sulfide (DMS) and biogenic aerosols formed from its atmospheric oxidation, such as methanesulfonic acid (MSA). This study examines relationships between changes in total sea ice extent north of 70 N and atmospheric MSA measurement at Alert, Nunavut, during 1980Nunavut, during -2009 at Barrow, Alaska, during 1997 and at Ny-Ålesund, Svalbard, for 1991. During the 1980-1989 and 1990 periods, summer (July-August) and June MSA concentrations at Alert decreased. In general, MSA concentrations increased at all locations since 2000 with respect to 1990 values, specifically during June and summer at Alert and in summer at Barrow and Ny-Ålesund. Our results show variability in MSA at all sites is related to changes in the source strengths of DMS, possibly linked to changes in sea ice extent as well as to changes in atmospheric transport patterns. Since 2000, a late spring increase in atmospheric MSA at the three sites coincides with the northward migration of the marginal ice edge zone where high DMS emissions from ocean to atmosphere have previously been reported. Significant negative correlations are found between sea ice extent and MSA concentrations at the three sites during the spring and June. These results suggest that a decrease in seasonal ice cover influencing other mechanisms of DMS production could lead to higher atmospheric MSA concentrations.

Organic functional groups in the submicron aerosol at 82.5° N, 62.5° W from 2012 to 2014

“…There have been no significant trends in either sulfate or BC at the observatory in Barrow, Alaska (Hirdman et al, 2010). Although measurements of methane sulfonic acid (MSA) from 1980 to 2009 show no net change in MSA at Alert (Sharma et al, 2012), MSA did increase from 2000 to 2009 associated with the northward migration of the marginal ice zone Sharma et al, 2012;Laing et al, 2013). Of the four northernmost observatories, the highest MSA concentrations are measured at Mount Zeppelin, likely due to its proximity to the waters between Greenland and northern Europe, that are a significant source of DMS from May to August (e.g., Lana et al, 2011).…”

Arctic aerosol life cycle: linking aerosol size distributions observed between 2000 and 2010 with air mass transport and precipitation at Zeppelin station, Ny-Ålesund, Svalbard

“…This is of course dependent on a nucleating gas and its precursors, which could be either locally emitted, e.g. DMS from the ocean (Sharma et al, 2012), or, perhaps less likely, transported into the Arctic during certain transport conditions. Single particle analysis (Behrenfeldt et al, 2008) further indicates that samples taken before the rapid transition mainly consisted of spherical "organic-like" particles originating from Eurasia, while particles sampled after the transition are associated with an enhanced abundance of particles associated with both marine sources within the Arctic (e.g.…”

Evidence for marine biogenic influence on summertime Arctic aerosol

“…In the Arctic, interactions between aerosol, clouds, and climate are complicated by a combination of high surface albedo; the dependence of cloud emissivity on droplet size and aerosol properties [e.g., Curry, 1995;Lubin and Vogelmann, 2006;Kay and Gettelman, 2009]; and the seasonal cycle in aerosol concentration, size, and composition [e.g., Shaw, 1995;Quinn et al, 2007;Sharma et al, 2012;Breider et al, 2014;Croft et al, 2016a]. Aerosol can exert a strong influence on Arctic climate, and changes in anthropogenic aerosol concentrations likely contributed to the magnitude of Arctic warming and impacted sea ice concentrations in recent decades [Najafi et al, 2015;Acosta Navarro et al, 2016;Gagné et al, 2017].…”