Impact of Chinese anthropogenic emissions on submicrometer aerosol concentration at Mt. Tateyama, Japan

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 submicrometer (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 2400 to 0500 were used to analyze free-tropospheric aerosol concentration. Monthly average volume concentrations were calculated for months with >50% daily data coverage. Volume concentrations of submicrometer aerosols were high in spring to early summer and low in winter. Significant increasing trends at 95% confidence levels were found for volume concentrations in winter-spring. Simulated monthly anthropogenic aerosol concentrations at Mt. Tateyama from results of regional aerosol modeling with 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 anthropogenic aerosol concentrations derived from China was high during winter-spring (60-80% of total anthropogenic aerosols at Mt. Tateyama). This accords with the increasing trend observed for winter-spring. Because SO ₄^2− is the dominant component of total anthropogenic aerosols, these results suggest that increasing anthropogenic emissions, especially for SO₂, in China, engender enhancement of submicrometer-diameter aerosols over Japan during winter-spring.