蒙古气旋爆发性发展导致的强沙尘暴个例研究

对2001年4月6～7日发生在中国北方的一次强沙尘暴过程,从沙尘源、干旱气候背景、天气系统及起沙和扬沙的动力机制进行了初步研究,揭示了强沙尘暴与蒙古气旋和高空急流活动的关系.得出:位于内蒙古西部的巴丹吉林沙漠和中部的浑善达克沙地,是沙尘暴的主要沙尘源区;持续两年的干旱是强沙尘暴形成的气候背景;蒙古气旋的爆发性发展和冷锋后大风是起沙的主要动力;湍流输送和高空急流出口区左侧气流辐散强迫形成的干对流上升气流是沙尘向高空输送的动力机制等结论.作者认为强沙尘暴是挟带大量沙尘的强干对流风暴.

A Case Study of a Severe Dust Storm Resulted from a Explosive Mongolia Cyclone

On April 6 to 7 of 2001, a severe dust storm occurred in North China.A preliminary study was conducted on the sand\|dust source, the formation of arid environment, the physical cause of Mongolia cyclone explosive development and the process that sand\|dust were blown and raised. The study uncovered the close relationship between the dust storm,Mongolia cyclogenesis and the upper level jet. Results showed:the primary sand\|dust sources came from Badain Jaran desert and Hunshandake desert in western and mid Inner Mongolia respectively; the weather without precipitation lasting a long period caused a dry climatic background of the severe dust storm; the explosive development of Mongolia cyclone and the strong surface wind caused by the cold front passage induced the dust storm; the physical cause of the upward transportation of large amount of sand\|dust lay in factors as follows: the turbulent mixing resulted from both the dynamic and thermal instability in the planetary boundary layer, and the strong/ dry/ ascending motion formed by coupling the cold frontal lifting in the low atmosphere with the divergence forcing which located at the left side of the upper\|level jet exit region in the upper atmosphere. The authors think that the severe dust storm is a strong/ dry /convective storm carrying a large amount of sand\|dust.