Tethered balloon-borne aerosol measurements: seasonal and vertical variations of aerosol constituents over Syowa Station, Antarctica 1National Institute of Polar Research, Tokyo, Japan
10 Sep 2013
2Graduate School of Environmental Studies, Nagoya University, Nagoya, Japan
*now at: Department of Earth System Science, Faculty of Science, Fukuoka University, Fukuoka, Japan
Received: 15 January 2013 – Published in Atmos. Chem. Phys. Discuss.: 26 March 2013 Abstract. Tethered balloon-borne aerosol measurements were conducted at Syowa Station,
Antarctica, during the 46th Japanese Antarctic expedition (2005–2006).
Direct aerosol sampling was operated from near the surface to the lower free
troposphere (approximately 2500 m) using a balloon-borne aerosol impactor.
Individual aerosol particles were analyzed using a scanning electron
microscope equipped with an energy dispersive X-ray spectrometer. Seasonal
and vertical features of aerosol constituents and their mixing states were
investigated. Results show that sulfate particles were predominant in the
boundary layer and lower free troposphere in summer, whereas sea-salt
particles were predominant during winter through spring. Minerals, MgSO4, and
sulfate containing K were identified as minor aerosol constituents in both
boundary layer and free troposphere over Syowa Station. Although sea-salt
particles were predominant during winter through spring, the relative abundance of
sulfate particles increased in the boundary layer when air masses fell from
the free troposphere over the Antarctic coast and continent. Sea-salt
particles were modified considerably through heterogeneous reactions with
SO42− CH3SO3− and
their precursors during summer, and were modified slightly through
heterogeneous reactions with NO3− and its precursors.
During winter through spring, sea-salt modification was insignificant, particularly
in the cases of high relative abundance of sea-salt particles and higher
number concentrations. In August, NO3− and its precursors
contributed greatly to sea-salt modification over Syowa Station. Because of
the occurrence of sea-salt fractionation on sea ice, Mg-rich sea-salt
particles were identified during the months of April through November. In contrast, Mg-free
sea-salt particles and slightly Mg-rich sea-salt particles coexisted in the
lower troposphere during summer. Thereby, Mg separation can proceed by
sea-salt fractionation during summer in Antarctic regions.
Revised: 06 June 2013 – Accepted: 28 July 2013 – Published: 10 September 2013
Citation: Hara, K., Osada, K., and Yamanouchi, T.: Tethered balloon-borne aerosol measurements: seasonal and vertical variations of aerosol constituents over Syowa Station, Antarctica, Atmos. Chem. Phys., 13, 9119-9139, doi:10.5194/acp-13-9119-2013, 2013.