Seasonal features of ultrafine particle volatility in the coastal Antarctic troposphere

Abstract

The size distribution and volatility of ultrafine aerosol particles were measured using scanning mobility particle sizer and thermodenuder at Syowa Station during the 46–47 Japanese Antarctic Research Expeditions (2005–2007). The relative abundance of non-volatile particles in a 240 C scan was approximately 20 % during the summer, whereas the abundance of non-volatile particles increased by >90 % during winter–spring. During the summer, most ultrafine particles were NH<sub>4</sub><sup>+</sup>, SO<sub>4</sub><sup>2−</sup> and CH<sub>3</sub>SO<sub>3</sub><sup>−</sup>, while major constituents of ultrafine particles were sea-salts (Na<sup>+</sup> and Cl<sup>−</sup>) in winter–spring. Therefore, the seasonal feature of volatility of ultrafine particles at Syowa might result from seasonal variations of the major aerosol constituents. Although the relative abundance of non-volatile particles was usually higher during winter–spring, the abundance dropped occasionally to <30 %. The lower abundance of non-volatile ultrafine particles during winter–spring corresponded to the lower number concentration of ultrafine particles and transport from the free troposphere over Antarctica

Seasonal variation of fractionated sea‐salt particles on the Antarctic coast

“…We conducted an aerosol measurement program at Syowa Station, Antarctica from 2004–2007 to ascertain physicochemical aerosol properties and atmospheric cycle of aerosols [e.g., Hara et al , 2010, 2011a, 2011b]. Aerosol sampling was conducted at Syowa Station (39.58°E, 69.00°S, 29 m) from February 2004 through December 2006 using a two‐stage mid‐volume impactor (MVI) with a back‐up filter holder (cut‐off diameter, 2 and 0.2 μ m in flow rate of ca.…”

“…−8.6°C. Indeed, the presence of sulfate‐depleted sea‐salt particles was observed at coastal stations [ Wagenbach et al , 1998; Jourdain and Legrand , 2002; Osada et al , 2001; Hara et al , 2004] and at an inland station [ Hara et al , 2004; Jourdain et al , 2008], so that the fractionated sea‐salt particles were used often as tracers of sea‐ice origin sea‐salt particles [ Rankin et al , 2002; Wolff et al , 2003; Hara et al , 2010, 2011a]. Because recent work [ Udisti et al , 2012] has implied a minor contribution of the fractionated sea‐salt particles at continental stations, unclear matters must be resolved before discussion can be made of sea‐salt fractionation in coastal and continental regions.…”

Seasonal variations and vertical features of aerosol particles in the Antarctic troposphere

“…The seasonal variation in the tethered balloon measurements, however, showed a good agreement with the continuous aerosol measurement near the surface at Syowa Station in 2005 (Osada et al, 2010a) and past (e.g., Ito et al, 1989Ito et al, , 1993. Aerosol concentrations in the winter-spring increased clearly under the storm conditions resulting from the cyclone approach (e.g., Ito, 1989;Hara et al, 2004Hara et al, , 2010Hara et al, , 2011. Because aerosol particles were composed predominantly of sea-salts (e.g., Na + and Cl − ) during winter-spring (Hara et al, , 2011, the number concentrations in the Antarctic coast during winter-spring might be associated with emission and transport of sea-salt particles from the ocean and sea-ice areas.…”

“…In contrast, CN concentration measured from ground-base CN measurements (D p > 10 nm) in 2005 indicated range of 18-5766 cm −3 (mean, 403 cm −3 ; median 273 cm −3 ). Although the highest CN concentration in the ground-base measurements was larger than those in tethered balloon measurements, the difference might be caused by an increase of CN concentrations in the ground-base measurements during the storm conditions as shown in Hara et al (2010Hara et al ( , 2011 as well as variations of the number concentrations in fine and coarse modes (as mentioned above). The seasonal features, however, were similar to those of the CN variation at ground level of the Antarctic coasts (Ito et al, 1993;Gras et al, 1993).…”

“…Aerosol concentrations in the winter-spring increased clearly under the storm conditions resulting from the cyclone approach (e.g., Ito, 1989;Hara et al, 2004Hara et al, , 2010Hara et al, , 2011. Because aerosol particles were composed predominantly of sea-salts (e.g., Na + and Cl − ) during winter-spring (Hara et al, , 2011, the number concentrations in the Antarctic coast during winter-spring might be associated with emission and transport of sea-salt particles from the ocean and sea-ice areas. In contrast to the winter-spring, storm conditions attributable to a cyclone approach are not frequent in the summer (Sato and Hirasawa, 2007), so that insufficient sea-salt emission might result in a lower concentration in fine and coarse particles in the summer.…”