The Effects of Snow Cover and Soil Moisture on Asian Dust: I. A Numerical Sensitivity Study

Abstract

Semi-arid regions of East Asian dust source areas are frequently covered by snow. We conducted a sensitivity study of East Asian dust storms to investigate the effects of snow cover and soil moisture with a global aerosol model (MASINGAR). The simulated dust concentration greatly underestimated the dust event in late March 2007 relative to the observed PM10 concentration. When the effect of soil moisture is not taken into consideration, the simulated total dust emission amount is almost doubled, and the simulated dust concentration is comparable or overestimated with regard to the PM10 observations. The result of the sensitivity study suggests that the underestimation of the dust event is due to excessive soil moisture, which suppresses the dust emission. In contrast, the simulated dust concentration of the control experiment is in agreement with the observed PM10 concentration in May, suggesting that the effects of snow cover and soil moisture on the dust event in May were very small. To improve our ability to forecast Asian dust events in March, the treatment of the hydrological cycles of snow in the land surface model and the soil moisture dependence of dust emission flux should be regarded as the key factors.