| 摘要: |
| 利用1987—2015年多个时相的Landsat卫星影像及同期气象和社会经济数据，结合多年建成区边界，利用单窗算法反演了地表温度，结合热场变异指数定量分析了西宁市城市建成区热岛强度时空演化特征，探讨了其与城市绿化程度、车辆数等要素的关系，提出了城市化进程中城市热岛效应的调控措施。研究结果显示：（1）西宁市夏季表现为“热岛”效应，冬季为“冷岛”效应；（2）西宁市热岛效应强度在时间序列有三个节点，2000年以前西宁市夏季和冬季白天各个热岛区面积变化不明显，2000年以后热岛区面积，尤其是较强热岛区面积和中热岛区面积都出现迅速增加的趋势，2003年热岛区面积达到最高，2003年以后热岛区面积渐渐回落，2011年以后又增强；（3）夏季“热岛”区面积变化趋势和冬季“冷岛”区面积变化趋势一致，且与建成区变化一致。 |
| 关键词: 城市热岛效应 单窗算法 地表温度反演 BCI 热场变异指数 西宁市 |
| DOI：10.7515/JEE182068 |
| CSTR：32259.14.JEE182068 |
| 分类号: |
| 基金项目:青海省科技厅自然科学基金项目（2016-ZJ-907） |
| 英文基金项目:Natural Science Fund Project of Qinghai Provincial Science & Technology Department (2016-ZJ-907) |
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| Spatio temporal change of urban heat island effect in Xining from Landsat image |
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LIU Xuemei, GAO Xiaohong, JIA Wei
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1. Key Laboratory of Physical Geography and Environmental Process in Qinghai Province, School of Life Science and Geography, Qinghai Normal University, Xining 810008, China
2. Qinghai Provincial Meteorological Bureau, Xining 810001, China
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| Abstract: |
| Background, aim, and scope With the implementation of the western development policy, Xining entered a rapid development stage at the end of twentieth century, and the scale of the city has been expanding, which has caused the urban heat island effect to become more and more prominent. Therefore, it is of great significance to study the spatial and temporal evolution characteristics and mitigation measures of urban heat island effect in Xining for the sustainable development of Xining. Compared with previous studies, the general urban heat island studies mostly take the urban administrative boundary as the suburb boundary. This paper takes the urban built-up area boundary as the urban and suburban boundary, and is relatively new. Materials and methods Using the Landsat satellite image from 1987 to 2015 and the same period of meteorological data and economic data, selected the single window algorithm to retrieve the surface temperature in Xining City from Landsat satellite image, combined with the thermal field variation and years of built-up area of the boundary, then the characteristics of temporal spatial evolution of Xining City urban heat island effect is analyzed in this paper. At the same time, the relationship between heat island intensity and vegetation, impervious surface, population and other factors was discussed. Finally, it puts forward the regulation measures of urban heat island effect in the process of urbanization. Results (1) Xining City shows “heat island” effect in summer and “cold island” effect in winter. (2) The intensity of heat island effect in Xining enhance slowly from 1987 to 2000, increase rapidly from 2000 to 2003, weaken gradually from 2003 to 2011, and enhanced after 2011. (3) The change trend of summer “heat island” area is consistent with that of winter “cold island” area, and is consistent with that of built-up area. Discussion The change of the heat island area in Xining shows that 2000 has become an important time node for the change of thermal environment. Before 2000, the area of heat island in Xining increased little, but there was a sharp increase after 2000. This is due to the implementation of the western development policy. Xining has expanded rapidly in the original built-up area, making the city development from a single center to a multi-center structure, and the increasing rate of greening can not catch up with the speed of development. Combined with the actual situation in Xining, this paper puts forward four relief measures for the heat island effect. (1) The artificial lakes should be dug near the industrial zone and the park. (2) Private cars should be controlled. (3) Green energy, such as abundant solar and wind energy in Qinghai Province should be developed. (4) Construction the counties around Huangzhong, Huangyuan and other Xining cities to attract and disperse the population. Conclusions (1) There was almost no change of heat island area in Xining before 2000. After 2000, the area of heat island area, especially the area of strong heat island area and medium heat island area, increased rapidly. In 2003, the area of heat island area reached the highest. From 2003 to 2011, the area of heat island gradually decreased, but increased again after 2011. (2) During the summer daytime, the intensity of urban heat island in Xining is positively correlated with the number of vehicles, built-up area, population and NDBI mean, and negatively correlated with urban greening rate, NDVI mean and BCI. (3) In winter daytime, the intensity of urban heat island in Xining is positively correlated with urban greening rate, NDVI, NDBI, BCI, and negatively correlated with the number of vehicles and built-up area. Recommendations and perspectives Due to the lack of remote sensing data and the poor quality of remote sensing data, the final screening image is not continuous in time, and the final result may lose some information. If there are more image data, better results should be obtained. In the study, it was found that during the winter, Xining was an obvious “cold island” in the daytime. Some studies have shown that the urban area in winter is “heat island” at night. However, due to the limitation of the imaging time of remote sensing data, the night thermal environment in the built area has not been studied in this paper. In future studies, we will focus on the heat island effect of winter nights in Xining. |
| Key words: urban heat island effect single window algorithm land surface temperature retrieval BCI thermal field variability index Xining City |
