近30年北京夏季降水演变的城郊对比

利用1975～2004年北京13个站的夏季降水资料，对30年来北京城区与郊区降水的时空变化趋势进行了对比分析，得出以下主要结论： 1）无论是城区站还是郊区站，北京的夏季降水量均呈明显下降趋势，且城区站的夏季降水量总体上要小于郊区站。2）从大兴、海淀和昌平3站夏季降水量的时间变化特征来看，位于城区盛行风向下风向的昌平下降趋势最不明显，在一定程度上表征了城市化对北京夏季降水的影响。3）地形仍然是决定北京地区降水分布的主导因素，但降水高值区存在向西南城区方向延伸或移动的趋势，而城市化可能是造成这种变化的一个原因。

Comparison of Summer Precipitation Evolution over the Last 30 Years between Urban and Rural Region of Beijing

Based on the analysis of summer precipitation data from 13 weather stations in Beijing area, a comparison of the summer precipitation evolution tendencies between the urban and rural region of Beijing is performed over a period of 30 years (1975 to 2004). Some conclusions are drawn in the light of the analysis: 1) The summer precipitations in both rural and urban area had a descending tendency, and the precipitations in urban area were generally less than those in rural area over the 30 years.2) The compari...