Abstract: Northern China is a region where dust storms occur frequently. Millions of tons of dust can be injected into atmosphere accompanying with the explosion of dust storms every year, especially in spring. Dust storms not only can cause huge damage to human lives and production activities, but also can influence the climate and environment due to physical and chemical effects of dust aerosols. However, available observations of the dust cycle are too limited to satisfy need of scientific research for indepth understanding dust activities in northern China. So climate models incorporating with dust schemes including the emission, transport and deposition are often used to explore processes of dust activities. Meanwhile, it is important to improve or develop a model which can be used to forecast a dust storm. Although some scientists used different models to investigate dust storms in northern China, previous results were discrepant based on different model kernels. The regional climate model version 3 (RegCM3), developed by the Abdus Salam International Centre for Theoretical Physics (ICTP), has been coupled with a desert dust module to investigate dust cycles and variations of dust aerosol optical depth (AOD). Although the RegCM3 has been widely used worldwide, there are few studies about its application in modeling dust storm events over northern China. Here the paper simulate a case of the severe dust storm of 9-11 April 2006 to evaluate the performance of this model. The paper mainly focus on two dust source regions of northern China. One is in the Taklimakan desert, the other is in the Gansu corridor. The simulated results show that the outbreak sites, synoptic situation and pattern of the corresponding AOD of this dust storm are successfully simulated, comparing with observation. This severe dust storm extensively exploded in the Tarim Basin and Turpan Basin at 6:00 a.m. on April 9 in 2006. 24 hours later, the sandstorm began to outbreak in central Gansu and the western Inner Mongolia under the effect of Mongolia Cyclone. The dust emission rate and column burden of those places were greater than 3 mg·m-2·s-1and 3 000 mg·m-2, respectively. The transportation of dust in lower and middle troposphere was eastward and its effect can reach the most provinces of east China. This dust storm caused the air quality decline of the cities in north China. In addition, distribution characteristics of AOD, which were well consistent with the distribution and values of TOMS AI, corresponded with those of dust emission rate and column burden. The AOD showed a decline trend from west to east with two maximums which was great than 2. One was located in the desert area of the Tarim Basin, Turpan Basin and Gurbantonggut. The other was close to the border between the Gansu corridor and western Inner Mongolia. Comparing with results from other models, the dust emission rate, transport and spatialtemporal distribution of AOD were reasonably simulated. The results show the validity of RegCM3 in simulating this severe dust storm event in northern China. However, more case studies and integrated analyses are needed before the model is practically used to forecast dust weather and air quality.

Key words: China, dust storm, air quality, regional climate model (RegCM3)