Original Research Papers
Vertical variations of sea-salt modification in the boundary layer of spring Arctic during the ASTAR 2000 campaign
Authors:
- K. HaraEmail K. Hara
- K. Osada
- C. Nishita
- S. Yamagata
- T. Yamanocuhi
- A. Herber
- K. Matsunaga
- Y. Iwasaka
- M. Nagatani
- H. Nakata
Abstract
Airborne and ground-based aerosol/gas measurements were carried out in Svalbard between mid-March and mid-April 2000. From the viewpoint of vertical features of sea-salt modification in the lower troposphere (1500 m) of the Arctic spring, more than 1000 individual sea-salt particles were analyzed with scanning electron microscopy energy dispersive X-ray spectrometry (SEM-EDX) in the present study. Individual particle analysis suggested a vertical gradient of sea-salt modification in fine sea-salt particles with an altitude of 59–1485 m above sea level (asl), e.g. chlorine liberation rates of 33.0% (212 m asl) and 81.0% (1266 m asl) on 15 March, and 72.7% (100 m asl), 83.8% (495 m asl) and 95.8% (1411 m asl) on 26 March. Sea salts may be dominantly modified with SO2 and SO4 2− under Arctic haze conditions with higher SO2 concentration (≥2 nmol m−3), whereas they are dominantly modified with NO3 − and reactive nitrogen oxides under Arctic background conditions, with [HNO3] of 0.15–1.3 nmol m−3 and [SO2] of 0.04–2 nmol m−3. Vertical trends in sea-salt modification suggested that it makes a significant contribution to the formation of reactive halogen species in the upper boundary layer and the lower free troposphere of the spring Arctic.
- Year: 2002
- Volume: 54 Issue: 4
- Page/Article: 361–376
- DOI: 10.3402/tellusb.v54i4.16671
- Submitted on 28 Jan 2002
- Accepted on 6 May 2002
- Published on 1 Jan 2002
- Peer Reviewed