北京市1993—2011年风速变化与下垫面粗糙特性关系研究

北京市近年来雾霾频发,大气污染物的扩散与风场环境及下垫面粗糙特性具有极大的相关性.本文首先利用1993—2011年的我国地面国际交换站气象观测资料对北京市地面风速风向年际变化特征进行了分析.结果表明,1993—2011年北京市平均风速呈现下降趋势,且自2006年来北京市风速下降尤为明显,北风出现频率明显下降.在此基础上,本文利用2007—2011年的ALOS PALSAR数据和夜晚灯光数据提取分析了北京市城镇用地扩展情况,进而结合下垫面粗糙特性的时空演变特征分析了北京市地区风速风向变化与下垫面粗糙特性的关系.分析结果表明,城市扩张造成的下垫面粗糙度的增加阻碍了北方来风,导致了北京市风场分布的变化及平均风速的减小.

The Relationship Research Between Wind Speed and the Underlying Surface Roughness in Beijing During 1993—2011

In recent years , Beijing has encountered serious air pollution problem .Atmospheric pollutants diffusion has a great correlation with the wind speed and the underlying surface roughness .Therefore,the 1993—2011 China ground international exchange station wind data are used to analyse the characteristics of the change of wind speed and direction in the ground .The results show that from 1993 to 2011 in Beijing,the average wind speed decreases .Since 2006 wind speed is significantly changed ,the analysis shows that the frequency of north wind decreased may be a mainly reason .On this basis,we use the 2007—2011 ALOS PALSAR and night light data to extract and analyse the land expansion of Beijing .To analyze the relationship between wind speed and direction change of Beijing with surface roughness .The results show that the city expansion causes the increase of roughness ,drags the north wind ,leeds to decreased of wind speed and changes the wind field in Beijing city .