基于气象站观测数据的京津冀城市扩展对气温变化的影响研究

城市扩展引起的区域增温效应一直都是城市热环境研究中的热门领域。本研究首先基于1980-2015年7期城市扩展遥感监测数据,通过熵值法构建了京津冀地区58个气象站周边2 km半径范围内城市扩展程度指数;然后使用四分位法对该指数进行分级,将站点划分为低度城市扩展（C1）、中度城市扩展（C2）和高度城市扩展站点（C3）;最后通过3类站点年和季节平均气温变化趋势对比分析,揭示了城市扩展对气温变化的影响程度及其贡献率。结果表明：① 1980-2015年京津冀地区几乎所有站点周边都有城市扩展现象,58个气象站周边城市扩展程度指数平均为0.377,C3类站点周边城市扩展程度指数为0.650;② 3类站点年和季节平均气温增温速率均表现为C1 < C2 < C3,C3类站点年平均气温的增温速率为0.536 ℃/10a;在季节平均气温上,C1、C2和C3站点春季的增温速率均最高,其中C3类站点的为0.637 ℃/10a,而夏季或秋季最低;③ 城市扩展对C3类站点年和季节平均气温增温影响和贡献率均高于C2类站点,对C3类站点年平均气温的增温影响和贡献率分别为0.342 ℃/10a和63.81%;在季节平均气温上,城市扩展对C2和C3类站点的增温影响均在冬季最高,分别为0.229 ℃/10a和 0.410 ℃/10a,而在春季或夏季最低;城市扩展对C2和C3类站点的增温贡献率均在秋季最高,分别为73.24%和82.96%,而在春季最低。

Effects of Urban Expansion on Air Temperature Change based on Meteorological Stations Data in the Beijing-Tianjin-Hebei Region

The warming effects caused by urban expansion have always been a hot topic in climate thermal research. Firstly, this study obtains the average proportion and expansion rate of urban-land area of 58 meteorological stations in Beijing-Tianjin-Hebei region within the radius of 2 km based on the 7 periods of remote sensing monitoring data of urban expansion from 1980 to 2015; builds expansion degree index of each meteorological station by entropy method. Then divide these meteorological stations into three types (these are lowly urban-expanded meteorological stations, moderately urban-expanded meteorological stations and highly urban-expanded meteorological stations) by quartering the expansion degree index of all stations. Finally, this study reveals the effects and its contributions of urban expansion through the comparative analysis of the annual and seasonal average temperature change trend of three types of meteorological stations. The results show that: (1) the surrounding of almost all meteorological stations has experienced urban expansion in Beijing-Tianjin-Hebei region during 1980-2015, the average of urban expansion degree index of 58 meteorological stations is 0.377, and the average of urban expansion degree index of C3 meteorological stations is 0.650; (2) the annual and seasonal average warming rates of three types of meteorological stations show as C1 < C2 < C3, and the annual average warming rate of C3 meteorological stations is 0.536℃/10a; the seasonal average warming rate of C1, C2 and C3 meteorological stations are the highest in spring, and the seasonal average warming rate of C3 meteorological stations is 0.637 ℃/10a, while the three types of meteorological stations have the lowest warming rate in summer or autumn; (3) The effects and its contribution rate of urban expansion on annual and seasonal mean warming rate of C3 meteorological stations are higher than that of C2 meteorological stations, the effects and its contribution rate of urban expansion on annual mean warming rate of C3 meteorological stations are 0.342 ℃/10a and 63.81% respectively; the effects of urban expansion on the seasonal average warming rate of C2 and C3 meteorological stations are the highest in winter, these are 0.229 ℃/10a and 0.410 ℃/10a respectively, while that of C2 and C3 meteorological stations are the lowest in spring or summer; the contribution rate of urban expansion on the seasonal average warming rate of C2 and C3 meteorological stations are the highest in autumn, these are 73.24% and 82.96% respectively, while that of C2 and C3 meteorological stations are the lowest in spring.