北京沙尘天气与源地气象条件的关系

本介绍了影响北京地区沙尘天气的沙尘源地,沙尘暴发生的条件和传输路径,分析了沙尘暴源地的气候要素特征及其对北京地区沙尘天气的影响,说明了北京沙尘天气发生和加剧的原因,影响北京地区沙尘天气的境外源地主要位于哈萨克斯坦,俄罗斯以及蒙古国境内,境内源地主要位于内蒙古和新疆,以及甘肃和青海的部分地区,沙尘天气发生必须具备三个条件：沙源,大风,气流辐合（垂直对流）,有沙源不一定起沙,但无沙源一定不起沙,沙尘暴源地的气候特征主要表现为冬季寒冷,夏季炎热,全年降水稀水,影响北京的沙尘传输路径,最主要的有两条,即西路传输和北路传输,北京沙尘天气与沙尘暴源地的春季降水比较结果表明,北京地区沙尘暴和浮尘天气发生次数与沙尘源区春季大气降水量有比较显的负相关关系,北京扬沙天气的发生与沙源区冬春季降水量相关关系不显,说明北京扬沙天气起因与源区降水没有明显的关系,北京扬沙天气主要受本地的自然条件和人为活动的影响。

THE RELATION BETWEEN SAND-DUST WEATHER IN BEIJING AND METEOROLOGICAL CONDITIONS OF DUST SOURCE AREAS

The present paper aims at introducing its investigation and analysis of the sandstorm disaster in Beijing and its relation with the sand-storm source areas. According to our research, the sandstorm source areas influencing Beijing's weather are not confined within China's own territories, they are chiefly coming from its three neighboring countries: Mongolia, Russia and Kazakhstan. At home, such areas are mainly the two autonomous regions in the north and northwest of China: Inner Mongolia and Xinjiang. Based on our investigation, the characteristic features of the climate in these areas are full of sand-dust due to the vast desert landscape. Our analysis has found the following three reasons in these home and international areas that contribute to the formation of the sand-dust weather in Beijing. The three reasons or conditions are respectively sand source, strong wind and violent vertical air current in the different periods of seasons in a year. Of course, it does not mean that the sand-storms are inevitable simply due to the existence of the sand dust surface ground in these original areas. Further analysis of ours shows that the climate in the source areas is characterized by the extreme coldness in winter and great heat in summer with scarce rainfall all the year around. Such a dominant reason has been further worsened by the two chief cold- and hot-air transmitting routes that contribute to causing the sandstorm weather in Beijing, one route is from the northwest, the other is from the north. It is also concluded through our investigation that the amounts of sand-dust storm and weather suffering from sandstorm in Beijing are in inversely proportional relation to the average rainfall in Spring in the source areas. However, it is not closely related to the rainfall in Spring in the source areas. Rather, it can be attributed to the dry natural conditions and the consequences of human activities in Beijing area itself.