Vertical variations of sea‐salt modification in the boundary layer of spring Arctic during the ASTAR 2000 campaign

• Published in: Tellus. Series B, Chemical and physical meteorology Vol. 54; no. 4; pp. 361 - 376
• Main Authors: HARA, K., OSADA, K., NISHITA, C., YAMAGATA, S., YAMANOCUHI, T., HERBER, A., MATSUNAGA, K., IWASAKA, Y., NAGATANI, M., NAKATA, H.
• Format: Journal Article
• Language: English
• Published: PO Box 805, 108 Cowley Road , Oxford OX4 1FH , UK Munksgaard International Publishers 01.09.2002; Blackwell
• Subjects: Chemical composition and interactions. Ionic interactions and processes; Earth, ocean, space; Exact sciences and technology; External geophysics; Meteorology; Particles and aerosols; Svalbard; Arctic Region; Nitrogen oxide; Scanning electron microscopy; Haze; Troposphere; X ray spectrometry; Concentration; Sea level; Dispersive spectrometry; Sulfates; Sulfur dioxide; Vertical gradient; Sea salt; Fine particle; Atmospheric boundary layer; Spring(season); Aerosols
• ISSN: 0280-6509; 1600-0889
• DOI: 10.1034/j.1600-0889.2002.201253.x

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 SO42− 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.