通过对北京市沙尘天气的变化特征、出现沙尘天气的天气形势、移动路径、关键区域和地表特征的分析,以及与降水量的相关分析,研究了北京市沙尘天气的变化趋势及其沙尘源地的基本特征。结果表明,近56年来,北京市浮尘、扬沙和沙尘暴等天气现象均呈现出不规则的波动减少的变化态势;进入北京的冷空气和沙尘主要有偏西、西北和偏北三条移动路径;蒙古气旋加冷锋是北京产生沙尘天气的最主要天气系统;影响北京的沙尘质点主要来源于我国内蒙古以及中蒙边境地区;从地表特征来看,北京市周边地区存在着大片的沙尘来源地。沙尘天气与降水量的相关分析表明,沙尘源区的春季降水对当年北京市三种沙尘天气的影响突出,而本地的降水更多的是仅仅影响当年的沙尘暴天气。要缓解北京市的沙尘天气灾害,除了在北京市及其周边地区植树造林、建立生态屏障外,还要加强对沙尘源地的监测与管理,坚持以草定畜、适度放牧,严防植被破坏,同时要及时预报沙尘天气的影响范围和持续时间,把危害降到最低程度。

Using the meteorological method,remote sensing method,geographical method,statistical method and HYSPLIT-4 model,the changing trend of dust weather,basic characteristics of sand-dust source areas and the correlation between the frequency of dust weather and the precipitation in Beijing and the sand-dust source areas are studied.The results showed that floating dust,raising dust and sandstorm weathers have an irregular fluctuant decreasing tendency in past 55 years.The cold air and dust entered into Beijing city have mainly three types routes from west,northwest and north routes.Mongolian cyclone along with cold front was the main weather situation that brings the dust weather of Beijing.The sand and dust particles mainly came from Inner Mongolia and the border between China and Mongolia.Besides,there are extensive sand-dust source areas surrounding the central districts and suburbs of Beijing.The correlative analysis showed that precipitation of the sand-dust source areas related closely to the frequency of dust weather of Beijing in spring,and local precipitation exerts an influence on the sandstorm weather mostly.In order to alleviate the calamity of dust weather of Beijing,people should plant trees to set up an outside ecological protective screen in the surrounding areas,strengthen the supervision on sand-dust source areas and predict the coverage and duration of possible dust weathers well in advance time.