A climatology of Northeast Asian dust events

In this paper, the synoptic features of Northeast Asian dust events in spring are studied. Using surface meteorological records for March, April and May of 2000, 2001 and 2002, the distribution of dust-event frequencies, possible dust-source regions and the synoptic conditions responsible for dust activities are examined. Four regions of frequent dust events are found in the domain of analysis. These are the Tarim Basin, the southern Mongolia and the Inner Mongolia Autonomous Region of China, the Hexi (Yellow River West) Corridor and the northern part of the Indian Subcontinent. The Tarim Basin has the highest dust-event frequency, with most of the events being weak ones (classified as dust-in-suspension). Dust events occur less frequently in the Gobi Desert, but they are often severe and widespread. Dust concentrations in the Tarim and the Gobi regions are found to be of similar order of magnitude with (averaged) maximum values reaching 1 mg m^-3. In different regions, dust events are generated by different synoptic systems. Over the Gobi, almost all dust events arise from the strong northwesterly winds associated with low-pressure systems. In the Tarim Basin, dust events are mostly associated with light winds. Strong northeasterly winds may affect the eastern and southeastern parts of the basin, generating dust storms. It is shown that topography plays a significant role in the transport of dust particles. A preferred route of dust transport is found to exist along the northeastern boundary, and another along the southern boundary, of the Tibetan Plateau. It is suggested that the mechanisms for dust emission in the Tarim Basin requires further investigation. © Gebrüder Borntraeger, Berlin, Stuttgart 2003.