景观格局影响下的南京市热舒适度动态变化

城市热舒适度的评价是判断热环境优劣的主要方式，其结果可为城市规划、改善城市热环境提供科学依据，而温湿指数(THI)综合反映了温度和湿度两个因子对人体热感的影响，是衡量城市热舒适度的一项重要指标。选取江苏省南京市作为研究区，以1994、2000、2010和2013年夏季Landsat遥感影像数据和土地利用现状数据为数据源，反演地表温度，并结合归一化水汽指数(NDMI)对传统温湿指数进行改进，在此基础上分别从宏观和微观两个层面分析了南京市热舒适度的动态变化，通过计算景观格局指数，分析不同热舒适度分级下景观格局指数的变化，统计了2.5 km尺度上单元格网温湿指数平均值及变异系数并对其与景观组成和结构特征的相关性进行了研究，从微观尺度上探讨城市景观格局与城市热舒适度之间的关系。结果表明：宏观上，从1994年到2013年景观格局对南京市热舒适度的影响不断加深，影响面积和强度都不断增大，城市热环境逐渐恶化；微观上，景观类型组成和结构对城市热舒适度有不同程度的影响，水体、耕地、林地能显著改善热舒适度，其中水体对热舒适度的改善效果最好，其景观优势度越大、分布越集中，效果越明显；反之，建设用地优势度越大、聚集度越高，热舒适度越差。 关键词： 城市热舒适度；改进型温湿指数；景观格局指数；动态变化；南京市

Impacts of Landscape Patterns on the Dynamic Changes of Thermal Comfort in Nanjing City

Evaluation of urban thermal comfort is the important means of assessing the quality of thermal environment for cities, as well as provides the scientific basis for improving urban thermal environment. The temperature-humidity index (THI) is an important indicator of thermal comfort indexes. In this paper, taking Nanjing City, capital of Jiangsu Province as the study area, we analyzed the impacts of landscape patterns on the dynamics change of thermal comfort. Four Landsat images of 1994, 2000, 2010 and 2013 were used to retrieve the land surface temperature (LST) and normalized moisture Index (NDMI). And the modified THI (MTHI) of Nanjing was calculated through LST and NDMI. The paper investigated the dynamic changes of thermal comfort in Nanjing City from the macro and micro scales during 1994 to 2013. Landscape metrics were calculated to explore the changes of various landscape patterns based on the different thermal comfort levels. The correlation between MTHI in virtue of 2.5 km fishnet and the composition and structure of the urban landscape was quantified, which can clarify the relationship between urban thermal comfort and urban landscape patterns on microscale. The results showed that the impacts of landscape patterns on thermal comfort in Nanjing has been increasing from 1994 to 2013 from the macro perspective, which was getting worse. The compositions and structures of different landscapes exert different impacts on urban thermal comfort from the micro perspective, among which cropland, forest, especially water can relieve the urban thermal comfort. The more proportion and greater concentration of cropland, forest and water body, the better they can improve the urban thermal comfort. Conversely the thermal comfort got worse when there were more aggregative built-up areas. Key words：Urban thermal comfort; The modified temperature-humidity index (MTHI); Landscape metrics; Dynamic changes; Nanjing city