Physical and chemical features of Asian dust aerosol mixed with haze during 14–19 March 2009

The physical and chemical features of the Asian dust event that affected Mongolia, China, Korea and Japan in March 2009 were analyzed using shared PM 10 concentrations monitored by each of the affected countries. This dust event was generated by a strong pressure gradient force at the surface located behind a low-pressure system that had developed in Mongolia. Dust was then transported over a long distance as the low-pressure system moved eastward and stagnated for two days. The daily average of the PM 10 concentration could be interpreted as the evolution of dust from its emergence in the source region through to transport to downstream regions. The water-soluble ions in the samples collected in Seoul during the dust period 15–17 March 2009 revealed distinct features of Asian dust with haze, in terms of both fine and coarse particles. Furthermore, the size distribution of the chemical components revealed a double peak in coarse and fine mode. Reconstruction of the chemical forms was estimated. These reconstructions reveal that high concentrations of secondary transformation forms were present in fine mode as well as in coarse mode during this dust event mixed with haze.