2006年4月11～12日平顶山市沙尘天气中尺度动力机制分析

A Mesoscale Dust Weather Dynamic Mechanism Analysis in Pingdingshan on April 11-12,2006

利用NCEP再分析资料(水平分辨率1°×1°)和同时间的探空、地面资料,分析了2006年4月在平顶山市出现的沙尘天气过程的天气气候背景、影响系统及这次过程的演变和动力机制,结果发现:这次天气过程的主要影响系统是强冷空气和蒙古气旋,强冷平流一方面使低槽、冷锋东移南压,另一方面与暖平流共同作用促进蒙古气旋的发展,造成平顶山市这次沙尘天气过程;沙尘上空螺旋度垂直分布及演变与沙尘天气的出现有一定的对应关系;高低空急流的稳定维持产生两个独立的次级环流,在直接环流北分支的下沉运动有利于高空急流动量下传,促进对流层中低层风力加大,冷锋南压,触发不稳定层结大气,驱动这次天气过程的发生、发展。

A dust weather process occurred in Pingdingshan on April 11 - 12, 2006. It was rare in corresponding historical period on its severe intensity and large extension. Based upon NCEP re - analysis data （horizontal resolution 1 °× 1 °） and the simultaneous sounding, surface air observational records, the weather background and influent system of this process were investigated, its evolutional regularity and dynamic mechanism were diagnosed as well. The result suggested that the main influent system on this process was strong cold air and Mongolia cyclone. The strong cold advection induced trough of low pressure and cold front eastward and southward moving. On the other hand, the co - action between strong cold and warm advection accelerated cyclone developed and produced this dust weather process;there was certain corresponding relation between the vertical distribution change of helicity above dust and the appearance of dust weather;The stable maintenance of high and low level jet gave birth to two independent second circulation. The north filiation of direct circulation was advantageous to high jet momentum descend down, it promoted wind speed in mid and low level of troposphere, pushed down cold front southward, triggered instable stratified atmosphere, drove the occurrence and development of dust weather.