Observation of Aerosol Scavenging by Falling Snow Crystals at Two Sites of Different Heights

[摘要] The aerosol concentration in the atmosphere and the number of aerosol particles attached to falling snow crystals were simultaneously observed in Sapporo and at the summit of Mt.Teine (1, 024m) in March 1978. As a result, it was found that the number of aerosol particles attached to snow crystals in Sapporo was about one order greater than at the summit of Mt. Teine. This shows that the snow crystals collected the airborne aerosol particles over Sapporo during their fall.The collection efficiency of aerosol particles by snow crystals was calculated on the basis of the observational data obtained in Sapporo.The collection efficiency by rimed snow crystals was about one order greater than that by the unrimed snow crystals. The aerodynamic effect and rain-out effect may be attributed to this large difference.As for larger aerosol particles from 0.4 to 10μm in diameter, it was found that the collection efficiency by the unrimed snow crystals increased with the increasing aerosol size, and ranged from 1×10-3 to 6×10-2. These values are almost in agreement with those experimentally obtained by other workers. As for aerosol particles smaller than 0.1μm in diameter, the collection efficiency was roughly estimated to be 1×10-2.

[学科分类] 大气科学