Influence of Arctic Oscillation on dust activity over northeast Asia

The northeast Asian dust process during the spring seasons in the years 1982-2006 was simulated by the Integrated Wind Erosion Modeling System (IWEMS). The influence of Arctic Oscillation (AO) on dust activities was investigated by analyzing surface observations and model simulations. There is a significant relationship between AO and dust activity; a positive AO phase is associated with decreased (increased) dust storm frequency in Mongolia (Taklimakan Desert) and enhanced anticyclonic (southeastward) dust transport over northwestern China (North China). The AO-dust relation is mainly due to changes in the westerly jet and geopotential height in the middle troposphere; a positive AO phase induces a northward shift of the polar jet, an intensified westerly jet over northern Tibetan Plateau, and a positive geopotential height anomaly over Mongolia. The northern shift of the polar jet reduces the frequency of intense cyclones in Mongolia, thereby causing a decrease in the dust storm frequency. The intensified westerly jet stream over the northern Tibetan Plateau increases the dust storm frequency in the Taklimakan Desert. The positive geopotential height anomaly over Mongolia initiates an anticyclonic dust transport anomaly in the middle troposphere over northwestern China. It also induces a southeastward dust transport anomaly over North China. The reverse situations are true for a negative AO phase.