论文部分内容阅读
城市热岛效应作为城市范围的一种典型气候特征,在近年来受到了广泛的关注。了解城市热岛时空演变及形成原因对缓解城市热环境和提高人居舒适性有着重要意义。以北京市中心城区为例,首先,基于Landsat卫星2005、2010、2016年的热红外影像数据反演得到地表温度,采用均值标准差方法对地表温度进行划分得到多等级的热岛强度,分析城市热岛的空间格局和随时间的演变规律;其次,提取不透水层、植被、裸土和水体4种典型地物类型,统计不同年份下各热岛强度之间的转移信息并计算相关的热力景观格局指数;接着,依据离市中心的距离将中心城区分为30级缓冲区,统计分析每一级缓冲区内各地物类型的面积比例与热岛强度信息。最后,以各地物类型的统计数据,结合离市中心的距离,建立各影响因子与热岛强度之间的多元关系模型,综合分析地物类型和市中心的距离变化对城市热岛的影响。结果表明:北京中心城区整体热岛强度呈逐年增长的趋势,高等级热岛强度的热力斑块面积逐步扩张,热力景观类型的多样性随时间推移呈下降态势。不透水层对热岛强度的影响较大,具体表现为不透水层盖度越高,热岛强度越大;热岛强度随离市中心距离的增大逐渐降低。
Urban heat island effect, as a typical climatic feature of urban areas, has received widespread attention in recent years. Understanding the spatial and temporal evolution of the urban heat island and the reasons for its formation is of great significance to alleviating the urban thermal environment and improving human comfort. Taking the downtown area of Beijing as an example, firstly, the surface temperature is obtained from the thermal infrared image data of Landsat satellite in 2005, 2010 and 2016, and the surface temperature is divided by mean standard deviation method to obtain multi-level heat island intensities. The urban heat island Spatial patterns and evolution with time. Secondly, four typical types of objects, such as impervious layer, vegetation, bare soil and water, were extracted. The information of heat transfer between different heat island intensities was calculated and the related thermal landscape pattern index Then, according to the distance from the city center, the downtown area is divided into 30 buffer zones, and the area ratio and thermal island intensity information of each type of object in each buffer zone are statistically analyzed. Finally, based on the statistics of each type of land and the distance from the city center, a multivariate relation model between each factor and the intensity of the heat island is established, and the influence of the type of land cover and the change of distance to the urban heat island is analyzed. The results show that the overall heat island intensity in central Beijing is increasing year by year. The area of heat patch of high-grade heat island gradually expands, and the diversity of heat landscape types declines with the passage of time. The effect of impermeable layer on the thermal island strength is greater, the specific performance of the impermeable layer is higher, the greater the intensity of the thermal island; the intensity of the thermal island decreases with the distance from the center of the city.