【作者】 赵玉广；

【导师】 沈桐立；

【作者基本信息】 南京气象学院 ， 气象学， 2003， 硕士

【摘要】 利用PSU／NCAR MM5模式，对华北地区“2002．3．20”强沙尘暴天气过程进行了数值模拟，并利用模式输出的各物理量对沙尘暴进行诊断分析，得出了华北地区沙尘暴的形成、发展机制。结果表明：沙尘暴是在干旱少雨的有利的气候背景下产生的。斜压槽和蒙古气旋是触发这次强沙尘暴天气过程的重要的天气系统，高空斜压槽和强锋区促使了地面蒙古气旋的发展和冷锋的加强，诱发沙尘暴天气。高空急流及其下方的Ferrel环流起到了高层动量下传和加强低层锋区的重要作用。沙尘暴期间，对流层高层大值位涡下传现象十分明显。500hPaPV2负值中心与地面强沙尘暴中心基本一致，它对沙尘暴的落区和爆发时间能起到一定的预示作用。另外，本次强沙尘暴天气出现在基本稳定的大气层结之中。地形对比试验结果表明，蒙古高原的地形有利于高空低涡和地面气旋的发展，涡旋强度越强其影响越明显。所以，蒙古高原的存在利于华北地区沙尘暴的发生发展。更多还原

【Abstract】 By using the PSU/NCAR MM5 model , we made a Numerical simulation aboutthe severe sand-dust storm that occured in the North China on 20March in 2002. We diagnosed and analysed the physical variation output field of the sand-dust storm, and we can get some concludes that how sand-dust storm occur and develop.The result shows that:the sand-dust storm occured in favorable climate background that is drought and rainless, the tilted trough and Mongolia cyclone are the important weather systems that caused the severe sand-dust storm, tilted trough and strong frontal zone caused the Mongolia cyclone developed and the clod front strengthened at surface, high jet and Ferrel circulation are the main reason that momentum spreaded downward from higher level and frontal zone strengthened on lower level. During the sand-dust storm, the high PV spreads evidently downward from the upper troposphere. The negative PV2 center on the level of 500hPa is corresponding with the center of severe sand-dust storm, and it is an important index for forecasting the sand-dust storm. Otherwise, the stratified atmosphere is stable when the severe sand-dust storm happened.The result of the terrain contrast test show:the Mongolia highland is of benefit to the development of cyclones of upper air and ground. The cyclone is stronger,the effect is evident. Therefore, the Mongolia highland is of benefit to the occurrence and development of the sand-dust storm at the North China.更多还原