No abstract

To study the climatic contribution to dust storm increases in Inner Mongolia in recent years, an analysis has been conducted of such factors in the last 40 years as annual and spring (March-May) precipitation, temperature, cold waves and strong gusty winds. In addition, such factors have been studied statistically regarding their impact upon atmospheric circulation with regard to the zonal circulation of Asia, the deep trough over East Asia and the geopotential height of Qinghai-Xizang Plateau. This study shows that the increased occurrences of dust storms likely result from a decrease in annual precipitation during 1999-2001; the precipitation recorded proved to be constantly below average, especially in spring. In addition, warmer temperatures with frequent cold-air outbreaks created unstable atmospheric stratification, thus leading to more gales and subsequently, more dust storms. In the springs of 2000 and 2001, large-scale atmospheric circulations provided the conditions for increased occurrences of dust storms due to stronger zonal circulation and a more westerly positioned trough over East Asia that became more intense in the winters. Furthermore, geopotential height over the Qinghai-Xizang Plateau seems to have an opposite trend as against dust storm frequency tendency. El Niño-southern oscillation activity might be an indirect factor.