Preprints
https://doi.org/10.5194/acp-2021-24
https://doi.org/10.5194/acp-2021-24

  26 Jan 2021

26 Jan 2021

Review status: this preprint is currently under review for the journal ACP.

Characterization of aerosol number size distributions and their effect on cloud properties at Syowa Station, Antarctica

Keiichiro Hara1, Chiharu Nishita-Hara2, Kazuo Osada3, Masanori Yabuki4, and Takashi Yamanouchi5 Keiichiro Hara et al.
  • 1Department of Earth System Science, Faculty of Science, Fukuoka University, Fukuoka, 814-0180, Japan
  • 2Fukuoka Institute for Atmospheric Environment and Health, Fukuoka University, Fukuoka, 814-0180, Japan
  • 3Graduate School of Environmental Studies, Nagoya University, Nagoya, 464-8601, Japan
  • 4Research Institute for Sustainable Humanosphere, Kyoto University, Kyoto, 611-0011, Japan
  • 5National Institute of Polar Research, Tokyo, 190-0014, Japan

Abstract. We took aerosol measurements at Syowa Station, Antarctica to characterize the aerosol number–size distribution and other aerosol physicochemical properties. Four modal structures (i.e., mono-, bi-, tri-, and quad-modal) were identified in aerosol size distributions during measurements. Particularly, quad-modal structures were associated closely with new particle formation (NPF). To elucidate where NPF proceeds in the Antarctic, we compared the aerosol size distributions and modal structure to air mass origins computed using backward trajectory analysis. Results of this comparison imply that NPF occurred in free troposphere during spring and autumn, and in the free troposphere and boundary layer during summer. Photochemical gaseous products, coupled with UV radiation, play an important role in NPF, even in the Antarctic troposphere. With the appearance of the ozone hole in the Antarctic stratosphere, more UV radiation can enhance atmospheric chemistry, even near the surface in the Antarctic. However, linkage among tropospheric aerosols in the Antarctic, ozone hole, and UV enhancement is unknown. Results demonstrated that NPF started in the Antarctic free troposphere already in the end-August – early September by UV enhancement resulting from the ozone hole. Then, aerosol particles supplied from NPF during spring grow gradually by vapor condensation, suggesting modification of aerosol properties such as number concentrations and size distributions in the Antarctic troposphere during summer. Here, we assess the hypothesis that UV enhancement in the upper troposphere by the Antarctic ozone hole modifies the aerosol population, aerosol size distribution, cloud condensation nuclei capabilities, and cloud properties in Antarctic regions during summer.

Keiichiro Hara et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Reviewer comment on acp-2021-24', Anonymous Referee #1, 02 Feb 2021
  • RC2: 'Comment on acp-2021-24', Anonymous Referee #2, 12 Apr 2021

Keiichiro Hara et al.

Keiichiro Hara et al.

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Short summary
New particle formation (NPF) occurred in the Antarctic free troposphere during spring and autumn, and in the free troposphere and boundary layer during summer. With the appearance of the ozone hole, more UV radiation can enhance formation of aerosol precursors and NPF in the free troposphere during spring. Here, we assess the hypothesis that UV enhancement in the upper troposphere by the Antarctic ozone hole modifies the aerosol and cloud properties in Antarctic regions during summer.
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