Biogenic sulfur aerosol in the Arctic troposphere: 2. Trends and seasonal variations

Abstract

An 11-year record of tropospheric aerosol methanesulfonate (MSA) in the Canadian high Arctic at Alert, Northwest Territories, from 1980 to 1991 shows marked seasonal and long-term variations. By using spectral-analysis techniques, the seasonal cycles and long-term variations have been quantified. There are two distinctly different seasonal peaks with levels of 12-23 ng m '3 in early May and 6-18 ng m '3 in July-August. Over the 11.3 years, the amplitudes of the MSA seasonal cycles and therefore the annual means of MSA concentrations decreased significantly by 33% (3% annually). So far there is no evidence of experimental artifact in this trend, but such a possibility will be further examined. Analysis of MSA monthly anomalies suggests that in spring they are weakly but significantly related to sea surface temperature anomalies (SSTA) in the North Atlantic west of the coast of continental Europe. In summer, MSA monthly anomalies are significantly correlated with SSTA in oceanic regions further north in the North Atlantic off the coast of Norway and in the northeast North Pacific. and summer [Turner and Liss, 1985; Bates et al., 1987; Burgermeister et al., 1990; Erickson et al., 1990; Leck and Rodhe, 1991; Tarfason, 1991]. What evidence existed on northern polar spatial and temporal variation of MSA prior to 1991 was presented by Li et al . [1993] and Li and Winchester [1989]. In a companion paper of the present study [Li and Battle, this issue] (hereafter referred to as paper 1), a detailed description of measurement methodology and other implications of the data is given. In addition, the contribution of marine biogenic aerosols to total sulfate is assessed using simultaneous observations of major aerosol ions, trace elements, and sulfur isotopes. The biogenic ratio of MSA to sulfate in air reaching northern regions is also examined. This paper augments the previously limited observations and analyses with an 11-year record of aerosol MSA measurements at ground level at Alert, Northwest Territories (82.5øN, 62.3øW), between July 1980 and August 1991. We present a

Measurements of aerosol and CCN properties in the Mackenzie River delta (Canadian Arctic) during spring–summer transition in May 2014

“…The later maximum occurs in July and August and is due to the local productivity of phytoplankton while the surface water is free of ice. The earlier maximum, which occurs around the time of our measurements, can be associated with long-range transport from marine source regions from the North Pacific (Li et al, 1993). This fits well with the source region we found for the air mass of PNSD c3 and can explain the presence of the Aitken-mode particles.…”

“…In summary, there is a number of reasons that can add to the observed bimodality of the size distribution, but small, comparably newly formed particles will make up the observed Aitken mode in all cases. Sources of the precursor gases forming these particles will differ from spring to summer, as mentioned above (Li et al, 1993).…”

Decadal trends in aerosol chemical composition at Barrow, Alaska: 1976–2008

“…Concentrations of MSA − , which is derived solely from the oxidation of biogenically produced DMS, begin to increase in April, peak in May through September, and decrease dramatically in October. The elevated concentrations of MSA − in late spring may be due to long range transport from source regions in the North Pacific (Li et al, 1993). By late June, local biogenic production of MSA − and nss SO = 4 becomes important as the ice melt begins and phytoplankton productivity in surface waters increases.…”

“…Concentrations of MSA − due to local production peak from May to September as the ice recedes and phytoplankton productivity in surface waters begins (e.g. Li et al, 1993;Quinn et al, 2002). In addition, there is a rapid release of DMS from the ice into surface waters and from under the ice into the atmosphere following the ice break up (Levasseur et al, 1994;Ferek et al, 1995).…”

Cloud and boundary layer interactions over the Arctic sea ice in late summer

“…For example, it is unclear if the aerosol particles that are required for both cloud liquid droplets and ice particles to form are advected into the central Arctic from lower-latitude marginal ice zone or ice-free regions (e.g., Li et al, 1993;Leck and Persson 1996;Chang et al, 2011) or if local sources play a critical role (e.g., Levasseur et al, 1994;Leck et al, 2002;Leck and Bigg, 2005;Orellana et al, 2011). Additionally, the importance of surface sources of heat and moisture in promoting cloud processes relative to in-cloud or advective sources is uncertain (e.g., Curry and Herman, 1985;Jiang et al, 2000;Morrison et al, 2012).…”