Journal of Geo-information Science >
Spatial-temporal Morphology Simulation of Beijing-Tianjin-Hebei Urban Agglomeration Thermal Environment based on Support Vector Machine
Received date: 2018-06-04
Request revised date: 2018-12-03
Online published: 2019-01-30
Supported by
National Social Science Foundation of China, No.18CGL048
Key Program of National Natural Science Foundation of China, No.41731286
China Postdoctoral Science Foundation Funded Project, No.2018M631383
Beijing Academy of Social Sciences Youth Research Project, No.2018B5186
Copyright
As an important part of regional ecology, the thermal environment of urban agglomeration has become a research hot topic in recent years. How to choose the thermal environment quantification mehod for the complex geomorphological features of urban agglomeration has been a difficult technical problem to be solved. Based on this, This study proposes a solution to multi-sample, nonlinear, non-stationary and high-dimensional function fitting. The calculation method is established, and the thermal environment surface model of Beijing-Tianjin-Hebei urban agglomeration based on support vector machine (SVM) is established to reveal the temporal and spatial morphological changes of the thermal environment of urban agglomeration. The results show: ①that the SVM model has theoretical and practical feasibility in describing the spatial distribution of the thermal environment of urban agglomerations with multi-core and multi-land-use types. It can optimize the differences locally through the Gaussian Kernel Function according to the overall spatial distribution of the thermal environment, and minimize the impact of default values on the fitting results of the model. Comparing with the control method, the spatial distribution pattern of heat island in urban agglomerations with complex geomorphologic features can be simulated with higher accuracy. ② In the process of fitting the surface of SVM model, accuracy and the time of fitting are important indexes to measure the results, and original image resolution is the decisive influencing factor. ③ In 2003-2013, the most obviously change regions of urban heat island effect are Beijing and Tianjin. The heat island area of the two cities increased by 7091 km square and 4196 km square, respectively. The spatial trend was developing continually year by year, and the trajectory of gravity center of the heat island had obvious spatial and temporal variations. Beijing's urban heat island is characterized by uneven growth in the southeast and slow growth in the west, while Tianjin's urban heat island is characterized by the expansion of city center to the surrounding areas. This study further enriches the quantitative methods of urban thermal environment assessment, and can provide quantitative and visual decision supports for urban agglomeration planning, urban construction, environmental protection and regional sustainable development practically.
YANG Hao , MENG Na , WANG Jing , ZHENG Yan , ZHAO Li . Spatial-temporal Morphology Simulation of Beijing-Tianjin-Hebei Urban Agglomeration Thermal Environment based on Support Vector Machine[J]. Journal of Geo-information Science, 2019 , 21(2) : 190 -200 . DOI: 10.12082/dqxxkx.2019.180271
Fig. 1 Study area after grid setting图1 网格化设置后的研究区域位置 |
Tab. 1 Criteria for dividing the level of surface temperature表1 地表温度等级区间划分标准 |
地表温度等级 | 温度范围 |
---|---|
低温 | Tni<Tmean-1.5s |
次低温 | Tmean-1.5s≤Tni<Tmean–0.5s |
中温 | Tmean-0.5s≤Tni<Tmean+0.5s |
次高温 | Tmean+0.5s≤Tni<Tmean+1.5s |
高温 | Tni≥Tmean+1.5s |
注:Tni为正规化后的像元值;Tmean为正规化后所有像元平均值。 |
Fig. 2 Verification of simulation results图2 模型模拟验证结果 |
Fig. 3 Two dimensional simulation results图3 模型模拟的二维结果 |
Fig. 4 Three dimensional simulation results图4 模型模拟的三维结果 |
Fig. 5 Support vector machine parameter optimization图5 支持向量机参数优化 |
Tab. 2 The moving distance and azimuth of the center of gravity of urban heat island in Beijing and Tianjin from 2003 to 2013表2 2003-2013年北京市和天津市城市热岛重心移动距离和移动方位角 |
时段 | 北京市 | 天津市 | ||
---|---|---|---|---|
移动距离/km | 移动方位角/° | 移动距离/km | 移动方位角/° | |
2003-2004 | 0.36 | 302.72 | 0.46 | 287.07 |
2004-2003 | 0.74 | 17.84 | 0.26 | 270.35 |
2003-2006 | 0.78 | 200.71 | 0.16 | 226.91 |
2006-2007 | 0.57 | 29.83 | 1.44 | 350.37 |
2007-2008 | 0.87 | 328.22 | 0.38 | 351.31 |
2008-2009 | 1.36 | 0.86 | 0.73 | 228.19 |
2009-2010 | 2.26 | 333.89 | 0.95 | 227.89 |
2010-2011 | 0.85 | 333.66 | 0.31 | 339.49 |
2011-2012 | 2.39 | 332.72 | 0.45 | 74.08 |
2012-2013 | 3.13 | 345.89 | 0.59 | 255.50 |
The authors have declared that no competing interests exist.
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