Relationship between the development of a convective mixed layer and dust weather in arid and semi‐arid regions of East Asia

Abstract

Mineral dust affects global and regional climates through radiative forcing. Herein the relationship between convective mixed layers and dust weather over arid and semi‐arid regions in East Asia is statistically analysed using operational surface‐station observation data and the lifting condensation level (LCL) height as a substitute for the mixed layer height. We divided the East Asia area into five regions (west/east Taklamakan Desert, west/east Gobi Desert and northeast China) and classified dust weather into three categories (floating dust, blowing dust and dust storm). Floating dust is the most frequent in the west Taklamakan Desert. All dust weather types are observed in the Taklamakan Desert even at low wind speeds but are seldom observed if the daily maximum LCL height is less than about 1,000 m. The floating dust events observed inside the Tarim basin seem to spread widely. In the Gobi Desert, when the maximum LCL height reaches about 3,000 m, all the dust weather types spread within the region. In all regions, the daily maximum LCL heights are higher in dust weather categories than in the no‐dust weather category. When a severe dust weather is observed in the Taklamakan and Gobi Deserts, the daily maximum LCL height reaches around 4,000–5,000 m above the mean sea level under higher wind conditions, suggesting that dust particles are easily raised from the boundary layer into the free troposphere during dust events in well‐developed mixed layer conditions. In the Gobi region, the frequency and areal extent of the blowing dust and the dust storm are higher than those of the floating dust. Therefore, the role of the deep mixed layers in the Gobi Desert is more important than that in the Taklamakan Desert.