Transport and evolution of a winter-time Yellow sand observed in Korea

Long-range transport of mineral dust such as Yellow sand (YS) is not restricted to the springtime periods in Northeast Asia. A YS phenomenon was observed during 25-27 January 1999, which was a remarkably distinctive episode in the occurrence time and intensity that had ever observed in the wintertime in Korea. This YS event was traced to be originated from the arid region of central and eastern Asia; the Gobi desert and Loess plateau. The traveling speed of the dust storm was found to be about 70 km h(-1) with it's horizontal size of larger than the whole Korean peninsula during this episode. Aerosol mass loadings changed by an order of magnitude within a few hours. The dominant ion components were SO42-, NO3-, Ca2+ and Na+ during the passage of YS. The mode diameter of these compounds of YS was around 4 mum, compared to 0.4-0.9 mum after the passage of YS. SO42- and NO3- concentrations were found to be well correlated with Ca2+ concentration in the coarse mode during the YS event, whereas they were well correlated with NH4+ concentration during the non-YS period, indicating a significant amount of SO42- and NO3- formations on the Ca2+-rich coarse aerosol during the long-range transport of YS. (C) 2001 Elsevier Science Ltd. All rights reserved.