2014 年 29 巻 S1 号 p. s117-s124
Aerial observations were conducted over the East China Sea in October 2009 (autumn), December 2010(winter) and March 2012 (spring). The base airport was Goto Fukue Airport in Fukue Island, Nagasaki, Japan. The flights were performed between Fukue Island and the southern offing of Jeju Island and the flight altitudes were 500, 1000, 2000 and 3000 metres. The concentration ratios of particulate nitrate(NO3-(p)) to inorganic total nitrate (T.NO3) were less than 0.5 in most of the flights except under high concentrations of dust particles (Kosa) or trans-boundary air pollutants. Most of the NO3-(p) would be comprised of NaNO3 formed by the reaction of gaseous nitric acid (HNO3(g)) with sea salt aerosols during the observations in autumn and winter, with the exceptions of October 17 and December 11, when high concentrations of Kosa were transported. In the spring observation, the fraction of NaNO3 in NO3-(p) was low and a large part of NO3-(p) would be originated from reactions of HNO3(g) with gas phase ammonia and soil dust particles.
