Abstract
A joint monitoring on dust-storms that occurred in East Asia from March until May 2003 has been carried out in this study. Our discussions include dust-storm observations in the source areas of China and Mongolia and measurements with satellites and ground monitors in central Korea. Differences were found in the definition and measurement of dust-storms. Over the source area of Mongolia there were 6 dusty days in March, 18 days in April, and 10 dusty days in May. In Inner Mongolia of northern China there were 4 dust-storms with 14 dusty days being observed over the three months. In central Korea, a sink area, there were 4 cases of weak dust-storms and 17 dusty days in the spring of 2003. The highest PM10 value was 607 $\mu$g$m^-^3$ and PM2.5 was 149 $\mu$g$m^-^3$, respectively. These observations identify the growing need for further universal observation practices and dust-storms reporting in the future. Observations indicated that snow covered the central part of the Gobi Desert, near the boundary of China and Mongolia, from December until mid March. Also, there were abundant rainfall amounts in the source region from March to May. This is in contrast to other years when the Gobi was relatively wet, producing unfavourable conditions for the formation of intense dust-storms. In addition, the very strong winds associated with intense cyclones and anticyclones were not apparent and the systems shifted northward during the spring. As a result, the frequency and intensity of observed dust-storms in 2003 in this region were very low. This confirms that there is variability in the frequency of dust-storm formation due to the current process of desertification and climate change.