1GSES, Nagoya University, Nagoya, Japan
2NIES, Tsukuba, Japan
3RIAM, Kyusyu University, Fukuoka, Japan
4Toyama Prefectural Environmental Science Research Center, Imizu, Japan
5Tateyama Caldera SABO Museum, Tateyama, Japan
Abstract. Rapid Asian economic development might engender secondary impacts of atmospheric aerosol particles over the western Pacific after conversion of gaseous pollutants such as SO2. To elucidate changes in aerosol concentrations in leeward areas undergoing remarkable industrialization, the number-size distributions of submicron (0.3–1.0 μm) aerosols were measured at Murododaira (36.6° N, 137.6° E, 2450 m a.s.l.) on the western flank of Mount Tateyama in central Japan during January 1999–February 2009. Nighttime data obtained from 24:00 to 05:00 (local time) were used to analyze free-tropospheric aerosol concentration. Monthly average volume concentrations were calculated for months with >50% daily data coverage. Volume concentrations of submicron aerosols were high in spring to early summer and low in winter. Significant increasing trends at 5% level were found for volume concentrations during December–January and March–April. Simulated monthly SO42− concentrations at Mt. Tateyama from results of regional aerosol modeling with SO2 emission inventory up to 2005 showed seasonal variation and winter–spring increasing trends similar to those of observed aerosol concentration. According to the model analyses, the contribution of Chinese SO42− concentration was high in winter–spring (ca. 80% of total SO42− at Mt. Tateyama). This accords with the increasing trend observed in winter–spring, suggesting that increasing SO2 emission in China engender enhancement of submicron aerosols over Japan, especially during winter–spring.