日本上空に飛来したダストの起源とその輸送構造についての解析

概要

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This study used a regional scale aerosol transport model (CFORS) to analyze the origin of dust layers over Japan and their 3-dimensional transport structures. CFORS dust fields were compared with NCAR-C130 airborne measurements, and captures many of the important observed features. Back trajectories of observed high dust levels reveal that dense dust layers within the boundary layer are transported mainly from the Gobi Desert and Loess Plateau, whereas those at the upper level (3-6 km) originate in the Taklimakan Desert. Transport altitudes of Gobi and Taklimakan dusts differed markedly. Further examination of dust transport using results of sensitivity simulation with controlled dust emission showed that Taklimakan dust has a higher transport altitude than Gobi dust because it is trapped in a higher potential temperature range when it is uplifted. We found that Gobi dust is transported mainly within the boundary layer between 45°N－50°N, whereas Taklimakan dust tends to be transported at altitudes between 4 km and 6 km centered at 40°N. Finally, we evaluated relative dust concentrations from sensitivity studies of total dust concentration for each research flight. Model results show that Gobi dust has the strongest fraction, which is mainly the contribution within the boundary layer.
九州大学の論文