AAAR 31st Annual Conference
October 8-12, 2012
Hyatt Regency Minneapolis
Minneapolis, Minnesota, USA
Abstract View
Wintertime Measurements of Scavenging Ratios of Sea-Salt Components for Snow and Rain in Niigata Prefecture, Japan
SHIN OHARA, Shin-ichi Fujita, Soichiro Sugimoto, Akira Takahashi, Central Research Institute of Electric Power Industry
Abstract Number: 676 Working Group: Aerosols, Clouds, and Climate
Abstract Scavenging ratios of Na$^+ for rain and snow were evaluated in order to examine the differences in scavenging process of sea-salt aerosol between snow and rain in Niigata Prefecture, Japan. Concentrations of chemical constituents in precipitation and aerosol were measured at a site in Niigata Plane, located along the Sea of Japan, during winter season of 2008 - 2010. The geometric mean of the scavenging ratio of Na$^+ for snow was greater than that for rain. As well as Na$^+, the geometric mean of the scavenging ratio of Cl$^- and Mg$^(2+) for snow was greater than that for rain, whereas the geometric mean of the scavenging ratio of non-sea-salt components including NH$_4$^+, nss-SO$_4$^(2-), NO$_3$^- for snow were almost equal to that for rain. The scavenging ratio of Na$^+ for snow remained constant with surface air temperature, while that for rain decreased with surface air temperature, falling to approximately one order smaller than that for snow. These results indicate that snow can be a more efficient scavenger of sea-salt aerosol than rain. Furthermore, the results suggest that the difference in scavenging ratio of sea-salt components between snow and rain would be attributed to relatively larger contribution of below-cloud scavenging to precipitation scavenging of sea-salt aerosol compared to non-sea-salt components, and the greater efficiency of below-cloud scavenging of sea-salt aerosol for snow than that for rain.