京津冀城市群低碳经济联系强度分形特征分析

应用分形理论与方法, 从低碳经济视角分析京津冀城市群特征, 考量京津冀一体化进程的发展现状。首先, 建立“全碳排”核算模型, 测算京津冀城市群中单个城市在社会经济发展过程中的资源消耗与污染排放。然后, 以单位CO₂ 排放人口支撑、GDP产出和道路面积承载为主要因素, 建立低碳经济联系强度引力模型和分维值测度模型, 计算 2006—2016年分别以北京和天津作为辐射中心源的低碳经济联系强度, 并采用源强叠加原理计算“京–津”双中心源辐射的叠加效应, 进而分析比较单源辐射与双源辐射叠加的差异。再后,选取代表性年份进行基于ArcGIS的低碳经济联系强度空间分析, 旨在找出单源辐射联系强度空间分布的差异对双源辐射叠加分维值的影响规律。最后, 以雄安新区作为第3个辐射中心源, 计算并分析三源辐射叠加的情况。分维值计算和分析结果显示: 2006—2016年京津冀城市群双源叠加的低碳经济联系强度分维值呈倒U型分布, 峰值出现在2012年, 说明2012年京、津双源对城市群内其他城市的低碳经济联合辐射效果最佳; 2007和2014两个年份, 分别以北京和天津作为中心源的低碳经济联系强度分维值差异较大, 导致双源叠加后的分维值出现倒挂现象, 即双源叠加后的分维值低于单源辐射能力较强者, 说明双源联合辐射效果较差。基于ArcGIS的低碳经济联系强度空间分析结果显示: 2012年“京–津”双中心源辐射的低碳经济联系强度源叠加结果呈现合理的空间分布——梯度有序且圈层分明, 是分维值达峰的主要原因。雄安新区作为第3个中心源加入后, 京津冀城市群低碳经济联系强度分维值明显提高。

Analysis of Fractal Characteristics of Low Carbon EconomicConnectivity in Jing-Jin-Ji Urban Agglomeration

Fractal theory and method is applied to analyze the characteristics of low carbon economy connectivityof Jing-Jin-Ji urban agglomeration. Firstly, a “full carbon emission” accounting model is established to calculatethe resource consumption and pollution emissions of a single city in Jing-Jin-Ji urban agglomeration in the processof social and economic development. Secondly, the low carbon economic connectivity gravity model and thefractal dimension measurement model are set up to calculate and evaluate the low carbon economic connectivitywhich centered on Beijing and Tianjin in 2006–2016. There are three main factors in the connectivity gravitymodel: the population support, GDP output and the road bear of every unit CO₂ emission. Furthermore, in order tocompare and analyze the difference between the single-point radiation source and the double-point sourceradiation, the superposition effect of the “Jing-Jin” twin-city radiation is calculated according the principle ofsource superposition. Thirdly, in order to find out the law of the influence of the spatial distribution of single-pointradiation connection intensity on the fractal dimension of the source superposition, the representative years areselected to carry out spatial analysis of low carbon economic connectivity based on the tool of ArcGIS. Finally,Xiong’an New Area is treated as the the third radiation center point to calculate and analyze the three-point sourceradiation superposition. The fractal dimension calculation and analysis results show that in 2006—2016, the lowcarbon economic connectivity of the Jing-Jin-Ji urban agglomeration have an inverted U-shaped distribution andthe peak appears in 2012, which reflect that Beijing and Tianjin had the best combination of low-carbon economyradiation in the urban agglomeration in 2012. The differences of the fractal dimension of low-carbon economicconnectivity are very large between Beijing as the central radiation source and Tianjin as the central radiationsource in 2007 and 2014, and the inversion of the fractal dimension appears after the dual source superposition, thatis the fractal dimension after superposition is lower than the one with higher radiation capacity in a single source,which means that the twin-city linkage is in low effect. The spatial analysis results of low carbon economicconnectivity based on ArcGIS show that in 2012, the results of the “Jing-Jin” twin-city radiation low-carboneconomic connectivity source superposition shows a reasonable spatial distribution—gradient order and distinctlayers, which is the main reason for the peak value of fractal dimension. When Xiong’an New Area is added as thethird central radiation source, the fractal dimension of the low carbon economic connectivity of the Jing-Jin-Jiurban agglomeration can be significantly improved.