北京地区两次沙尘(暴)天气过程对比分析

通过对 2 0 0 0年 4月 6日和 4月 9日北京地区两次沙尘 (暴 )天气过程的对比分析认为 :蒙古气旋型和不伴有气旋的西北槽型所造成的北京沙尘天气的严重程度不同 ;沙源地区中低层较强上升运动的主要作用是将当地沙尘垂直输送到空中 ,然后在70 0hPa较强西北气流的引导下将卷起的沙尘水平输送到下游地区 ;不稳定层结又加强了沙尘天气 ;沙尘暴区上空z 螺旋度分布的特征是高层为负值 ,低层为正值 ,对流层中低层螺旋度正的大值区与卫星云图显示的沙尘暴区具有较好的一致性 ,对沙尘暴的预报有一定的指示意义

Comparison Analysis of Two Dust Devil Events in Beijing Area

Two dust devil events in Beijing area on 6 and 9 April 2000 are analyzed. The result shows that the two events caused by the Mongolia cyclone and the northwest trough without cyclone are different. In the area of sand source, the strong ascending movement at the middle and low level lift the sand and dust to sky vertically, then the strong northwest airstreams at 700hPa transport them to the downriver area flatly; the instable atmospheric structure could strengthen the dust devil; the distribution feature of z-helicity of the dust devil area is negative at the high level and positive at the lower, and the positive area is coincident with the satellite image.