热岛效应是城市气候最显著的特征之一。土地利用方式及土地覆盖的改变，如城市化和道路建设是导致热岛现象的重要原因之一。然而目前针对道路属性（道路密度及类型）对城市热岛效应的影响研究还较缺乏。本研究运用2012年成都市不同时次（冬夏季）的遥感数据及城市道路交通专题图，运用3S技术探讨道路密度对城市热岛效应的影响以及不同类型道路对城市热岛效应的热贡献。研究表明：（1）成都市热岛效应明显，市区地表平均温度显著高于郊区且热岛强度呈现夏强（3~4℃）冬弱（2.5~3℃）、夜强昼弱的特征。日间城市热岛效应呈现多热中心的分布模式，但冬夏季热岛中心位置不同。夏季日间热中心位于城市的西南部和中东北部，最高可达32.66℃，而冬季日间城市的西南部地表温度较高且热中心主要分布于城市边界地区，地表温度超过16℃。无论冬夏，夜间城市热岛效应均呈现环状分布特征，即从城市边缘到中心，地表温度逐渐升高，夏季城乡地表温差高达4.37℃而冬季达到2.82℃。（2）成都市区道路呈现“圈层型+辐射型”分布模式，道路密度与道路的分布有关，城市南部及西南部的道路密度高于北部区域。（3）无论冬夏，道路密度与地表温度正相关，但两者相关性呈现昼弱夜强的特征，其中夜间相关系数达到0.5左右。对热效应贡献度指数、热单元权重指数、区域热单元权重指数3个指标的分析都表明无论冬夏、无论昼夜，市区分布面积最广的三级道路对城市热岛效应的热贡献最大，其热效应贡献度指数均在95%以上，其次是二级道路，各项热效应贡献度指数为45%~80%。本研究结果将有助于未来城市建设和道路规划，并为缓解城市热岛效应提供理论支持。%The heat island effect is often one of the most evident characteristics of urban climates. Land use/cover changes such as urbanization and road building, are some of the most important factors that induce heat islands. Road properties, including road density and road type, may determine the magnitude of urban heat islands, but such effects have not previously been explored. In this study, we evaluated the effect of road density and the contribution of different road types on urban heat islands using multi-time (winter and summer) Modis data and city transportation maps with 3S technology. The results showed that: (1) The urban heat island effect in Chengdu was very apparent and of high intensity in summer (3~4℃) but weak in winter (2.5~3℃). During daytime, there was a polycentric pattern of heat island, and the central of heat island varied between summer and winter. In summer, the areas with the highest land surface temperature (32.66℃) was in the southwest and the central northeast part of the city. In winter, the land surface temperature in the southwest section of the city and at the city boundary was higher, oftern over 16℃. At night, there was a ring distribution pattern of the urban heat island both in summer and winter, and the land surface temperature decreased from the central of the city to the suburbs. The difference of the land surface temperature between the city and suburbs was 4.37℃ in summer and 2.82℃ in winter;(2)The road system in Chengdu showed a “ring and radiative” distribution pattern, and road density was closely related to the road distribution. The road density in the south and southwest part of the city was higher than that in the northern part;(3)Both in winter and summer, the land surface temperature was significantly correlated with road density, and the coefficient correlation was higher at night (r=0.5) than that in daytime. Thermal contribution index, thermal unit weight index and thermal unit weight index indicated that the third-class roads contributed the most to the urban heat island effect (>95%), much greater than secondary road (45%~80%). These results are expected to provide critical information for decision makers and land managers for management of urbanization and road building, which may mitigate the urban heat island effect.
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