北京地区风沙活动的变化趋势

10年来北京地区风沙活动大幅度减少。与1980年以前的多年平均值比较1991-1992年北京地区10站平均大风日数只有34%,风沙日数为21.9%。风沙日下降的原因主要是地面绿化后就地起沙迅速减少。但如果上风地区绿化工作不跟上,还会影响北京的风沙活动。

THE CHANGING TREND OF SAND AND WIND ACTIVITIES IN BEIJING

There was a ohvious decrease of sand and wind activities during the last tne years in beijing.The average windy days and the sand-driving wind days from 1991 to 1992 were 34% and 21.9% respectively as compared with the multi-year average values before 1980.The reason of decrease of sand-driving wind days was that the sand producted in Beijing area itself decreased because of a better-green-layer above land.But if the greening-work in the upper-reach of wind area delays, it will have aimpact on the sand and wind activities in Beijing.