【摘要】 对黄土高原地区沙尘暴日数与年降水量关系的分析表明,在黄土高原地区存在着一个原生沙尘暴带和一个次生沙尘暴带,后者是人类破坏植被、改变土地覆盖状况的结果。发现原生沙尘暴带与次生沙尘暴带之间存在着跃变现象,这一现象发生在年降水量为300mm左右的地区。这表明,对于沙尘暴带的演化而言,年降水量为300mm左右的地区是一个超常不稳定带。更多还原

【Abstract】 Based on the data of sandstorms and precipitation,a study of sandstorms in the Loess Plateau and the neighboring areas has been made.Through analysis of relationship between mean annual number of sandstorms and mean annual precipitation,an original sandstorm zone and a secondary high-frequency zone of sandstorms have been found.The latter was formed as a result of human activities such as vegetation destruction and waste-land cultivation.The secondary sandstorm zone is 350 km to 500 km away from the original sandstorm zone,reflecting that the sandstorm zone in the Loess Plateau area has been shifted 350 km to 500 km to the southeast,as response to human impacts.Some abrupt change has been found around the belt of mean annual precipitation of 300 mm,where the original sandstorm zone suddenly shifts to the secondary high-frequency zone of sandstorms.Hence,this transition area can be regarded as an abnormally unstable area.更多还原