Mineral dust layers in snow at Mount Tateyama, Central Japan: formation processes and characteristics

Deposition of water-insoluble dust was measured in winter snow deposited at Murododaira (2450 m) on the western flank of Mount Tateyama in central Japan. An analysis of temporal variation in atmospheric aerosol concentration, incremental snow height and concentration of dust in the snow cover suggests that wet deposition is the major process in forming thicker dust layers in the snow cover at Mount Tateyama. Dust layers in the snow cover contain Ca-rich materials typically found in Asian dust (Kosa) particles. Volume size distributions of dust particles in the snow showed single and bi-modal structures having volume median diameters from 6–21 μm. Dust profiles in snow cover over the last 6 yr reveal frequent sporadic high dust concentrations in spring and large year-to-year variations in the amount deposited. The average amount of dust deposition (7.7 g m−2) from winter to spring at the site was close to the long-term averages of annual flux obtained from sea sediment near Japan, implying that dusty precipitation in spring contributes to annual deposition of aeolian mineral dust.