2017 Volume 32 Issue 1 Pages 44-51
In order to obtain a seasonal variation of Asian dust (Kosa) transport frequency over Japan, the number–size distribution of atmospheric aerosol particles was measured using an optical particle counter (OPC) at Mt. Tateyama during 2004–2014. The OPC data were used to calculate the volume concentration of coarse particles (> 1 μm). Data of light detection and ranging (LIDAR) systems at Toyama near the mountain site were also used to assist dust event detection at Mt. Tateyama during the daytime.
The dust event days per month at Mt. Tateyama were frequently detected in spring but not found in September, showing a similar seasonality of Kosa events based on the visibility reduction at meteorological observatories. In July and August, a few dust events were detected at Mt. Tateyama. Analysis of average winds and backward air trajectories suggested that the dust events would be observed at Mt. Tateyama even in summer because of frequent influence of westerly winds during summer.