【作者】 屠妮妮；

【导师】 朱伟军； 矫梅燕；

【作者基本信息】 南京信息工程大学 ， 气象学， 2006， 硕士

【摘要】 本文对2002年4月5～9日发生在我国华北、东北和蒙古国的强沙尘暴天气过程中蒙古气旋的发生、发展和强沙尘暴成因分别进行了诊断分析和数值模拟分析。首先对蒙古气旋的环流背景进行诊断分析;然后利用沙尘天气数值预测系统对这次过程进行数值模拟,在此基础上,利用模式输出的资料研究地形条件、环境场特征以及下垫面属性对蒙古气旋的发生发展、沙尘天气强度的影响作用;最后将本次过程与2003年4月13～15日由蒙古气旋引发的扬沙天气进行了对比分析,得出以下几点结论: (1) 这次气旋发展发生在斜压区中,气旋的发展阶段以温度平流的作用为主,大气斜压性的作用不可忽视。沙尘暴过程主要是由气旋冷锋及锋后地面大风触发的,地面大风的形成与气旋发展、锋后冷平流以及高空急流动量下传有关。 (2) 通过降低地形高度的试验表明,地形对蒙古气旋的走向与强度存在显著的影响,降低地形高度造成气旋位置偏北,低空急流减弱,最后造成沙尘天气强度减弱;减弱高层风场,高低空急流减小,气旋发展偏慢强度偏弱,沙尘浓度减弱;增加低层温度即减弱冷空气强度,加快气旋发展速度;扩大土壤含水量增强临界摩擦速度,使得瞬时起沙量减少,减弱沙尘浓度。 (3) 将由蒙古气旋引发的两次不同强度的沙尘天气过程进行对比分析结果表明,相同的影响系统会造成不同强度的沙尘天气,由于冷空气的强度、高空环流形势、蒙古气旋的移动路径等性质有所差异,造成这两次不同强度的沙尘天气,反应蒙古气旋的强度与沙尘天气的强度不成正比。更多还原

【Abstract】 In this dissertation, the genesis and development of Mongolia cyclone related to a severe dust storm, which occurred during 5-9 April, 2002 in the area of north-east china, north china and Mongolia and the cause of severe dust storm are diagnostically analyzed and simulated respectively. In the first part, we analyze circulation background of the Mongolia cyclone, and then simulate it with the integrated dust numerical prediction system, furthermore we discuss the effect of terrain condition, ambient fields, the property of underlying surface on the genesis and development of Mongolia cyclone and the intensity of dust-storm, finally, we compared it with blowing dust on 13-15 April, 2003 resulted from Mongolia cyclone, getting some conclusions as follows:(1) The development of the cyclone commences in baroclinicity region at the occurrence of the cyclone, the main contribution to the intensification of cyclone comes from the thermal advection, it is must not be overlook the function of the atmospheric baroclinicity. This dust weather case was mainly caused by cyclone cold front and surface high wind behind the cold front. The formation of the surface strong wind is caused by the cyclogenesis, clod advection behind the cold front and the downwardly transmission of the upper level jet momentum.(2) The experiment of reducing the height of the terrain shows that the terrain has a notable influence on the orientation and intensity of the Mongolia cyclone, because the reducing of the height would lead the more North of cyclone, the weaker of the low jet, at last resulting in the weaker of dust storm;the upper level and low level jet decreases by reducing the upper level wind field, the more slowly and weaker of the development of cyclone, and thinness of dust storm;increasing the low level temperature viz weaking the intensity of cold air, improving the development of cyclone;expanding the containing water of soil to boost up the speed of critical friction, at the same time, weak the amount of instantaneous blowing sand and the concentration of dust storm.(3) The results of comparative analyse of different intensive dust stormresulting from Mongolia cyclone show that the same influence system may cause the different intensive dust, because it is not direct ratio for the intendity of dust weather, because of the different cold air, the upper level circulation, and the moving road of Mongolia cyclone causing different dust storm.更多还原