%0 Journal Article
%T Seasonal variations and vertical features of aerosol particles in the Antarctic troposphere
%A K. Hara
%A K. Osada
%A C. Nishita-Hara
%A T. Yamanouchi
%J Atmospheric Chemistry and Physics (ACP) & Discussions (ACPD)
%D 2011
%I Copernicus Publications
%X Tethered balloon-borne aerosol measurements were conducted at Syowa Station, Antarctica during the 46th Japanese Antarctic expedition (2005每2006). The CN concentration reached a maximum in the summer, although the number concentrations of fine particles (Dp>0.3 米m) and coarse particles (Dp>2.0 米m) increased during the winter每spring. The CN concentration was 30每2200 cm 3 near the surface (surface 每 500 m) and 7每7250 cm 3 in the lower free troposphere (>1500 m). During the austral summer, higher CN concentration was often observed in the lower free troposphere, where the number concentrations in fine and coarse modes were remarkably lower. The frequent appearance of higher CN concentrations in the free troposphere relative to continuous aerosol measurements at the ground strongly suggests that new particle formation is more likely to occur in the lower free troposphere in Antarctic regions. Seasonal variations of size distribution of fine-coarse particles show that the contribution of the coarse mode was greater in the winter每spring than in summer because of the dominance of sea-salt particles in the winter每spring. The number concentrations of fine and coarse particles were high in air masses from the ocean and mid-latitudes. Particularly, aerosol enhancement was observed not only in the boundary layer, but also in the lower free troposphere during and immediately after Antarctic haze events occurring in May, July and September.
%U http://www.atmos-chem-phys.net/11/5471/2011/acp-11-5471-2011.html