南京市热场分布特征及其与土地利用/覆被关系研究

文章采用Landsat ETM⁺热红外波段反演LST,分析南京市热场分布规律,构建了土地覆被指数LCI定量表示热场分布特征与土地利用/覆被的关系。结果表明:南京市存在三个连续分布且范围较广的热岛中心,主要分布在工业区;建成区平均温度比郊区高0.972℃;土地利用/类型的空间格局总体上决定了城市热场的空间分布,下垫面介质的热特征和生物学特征差异是地表温度不同的根本原因,工业热源是南京市热岛形成的重要因素;LCI可以和城市气候模型、水文模型结合起来运用,为城市热岛提供一种新分析方法。对某一特定区域而言,随着城市化水平的提高,单位面积内LCI值逐渐减小。

Distributional Characteristics of Urban Thermal Space and Relations with Land Use/Cover of Nanjing

How to analyze distributional characteristics of urban thermal space and its quantificational relations with land use/cover is one of the difficult problems. Many methods can be used to study the urban heat island. Remote sensing dominates over traditional research methods because of speediness, impersonality, ninety, macroscopical feature, strong periodicity so that remote sensing becomes a kind of good tool to study urban heat island. The paper analyzed space distributional rules and the cause of formation of urban thermal space in Nanjing by using Landsat ETM⁺ of 2002 and established land cover index based on the relations between LST and NDVI. The result indicates that there are three centers of heat island in Nanjing, mainly in industrial region, not in commercial or residential areas. The spatial distribution pattern of land use/cover affects wholly the distributional pattern of the urban heat space; the difference of surface material's thermal and biologic feature is the essential reasons of surface temperature, because of different surface materials with different heat capacity, heat conductivity, inertia and NDVI; industrial heat has important effect on heat island. The partitioning of sensible and latent heat fluxes and, hence, surface radiant temperature response is modulated both by surface soil content and vegetation cover. The surface radiant temperature response is a function of varying vegetation cover and surface soil water content. The land cover index (LCI) can reflect surface soil water content and vegetation cover, explain the essential reasons that each land use/cover contributes differentially to urban heat island. Such an index can allow changes in land use at neighborhood-scale to be input in the initialization of atmospheric and hydrological models, as well as provide a new approach for urban heat island analysis. The LCI of urban land use is smaller than the LCI of water, forest and cropland. LCI is smaller; the intensity of urban heat island is stronger. For a special region, LCI will increase gradually per unit with higher urbanization level.