1916—2020年北京城市变迁及其与区域气候演化的关系

Spatio-temporal evolution of urbanization and its relationship with regional climate change in Beijing over the past century

剖析百年尺度的城市变迁与气候要素变化对提升区域气候演变机理的认知具有重要意义。本文基于卫星遥感图像、社会经济数据和气象站点实测等数据,采用人机交互解译方法,刻画了1916—2020年北京城市扩展过程。利用滑动平均法和Mann-Kendall趋势检验方法,分析了关键气象要素的变化特征,从而揭示了百年尺度城市土地利用变化和社会经济发展与区域气候变化之间的关系。研究表明:1916—2020年北京城市土地面积增长了64.48倍,围绕中心地域呈圈层式蔓延扩展,呈现“缓慢—加速—减速”的扩展模式,城市扩展速度在2000—2010年达到峰值,为70.12 km^(2)/a。1916—2020年北京的5 a滑动平均气温和年降水量分别为12.25℃和588.6 mm。随着城市发展,1916—2020年北京市5 a滑动平均气温以0.22℃/10a波动上升,1978年以来升温显著。年降水量则呈现波动下降趋势,速率为9.37 mm/10a。城市不透水面的加速扩张可能造成地表能量收支的改变,从而引发城市变暖。城市化率与气温升高具有协同关系,不同时段差异显著,1916—2020年北京城市化对区域升温的贡献为20.83%。另一方面,地表能量收支改变与空气污染物排放增加可能导致北京城市地区降水减少。本文结果可为提升北京城市变迁对区域气候演变影响过程和机制的认知提供科学参考。

Understanding the mechanisms of regional climate evolution requires extensive research on long-term urbanization and meteorological elements.The various data sources and an interactive interpretation method were utilized to reproduce the urban expansion in Beijing over the past century.The relationship between urban development and regional climate change was then determined by using the moving average method and the Mann-Kendall trend test.We found that the area of urban land in Beijing increased 64.48 times from 1916 to 2020,expanding in a circle around the central region.The rate of urban expansion peaked at 70.12km^(2)/a between 2000 and 2010.The average annual temperature and precipitation from 1916 to2020 in Beijing were 12.25℃and 588.6 mm,respectively.The 5-year moving average temperature fluctuated upward by 0.22℃/10a over the past century,with a notable warming trend since 1978.Precipitation trended downward at a rate of 9.37 mm/10a.The accelerated expansion of the impervious surface area in the city might lead to urban warming by altering the surface energy balance.The rate of urbanization and the regional temperature rise were positively correlated,with urbanization accounting for 20.83%of the regional warming in Beijing.Changes in the surface energy balance and an increase in air pollution emissions might result in a decline in precipitation.The results provide scientific resources for advancing knowledge of the processes and mechanisms by which urban development influences the regional climate change.