A study on time-space character of urban heat island effect and relations with LUCC based on remote sensing

Abstract

This paper takes Nanjing city as an example, analyzes diurnal and seasonal characteristics of UHI by eight granule and sixteen scenes MODIS, respectively. The land cover index (LCI) has been constructed to get a quantitative analysis about the changes of land use/land cover how to affect the distributional characteristics of urban thermal space. The results indicate the diurnal intensity of UHI is stronger than night's no matter whichever season it happens, but different season has different UHI intensity. The strongest intensity of UHI happens in autumn, the second in summer, the third in spring, the last in winter. The most extensive in scope occurs in summer, the second in autumn, the third in spring, the last in winter. There are three centers of heat island in Nanjing, mainly locating in industrial region, not in commercial or residential region. The spatial distribution pattern of land use/land 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 distribution difference. Artificial heat has important effect on heat island. The LCI can reflect surface soil water content and vegetation cover and explains the essential reasons that each land use/land 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 provides a new approach for urban heat island analysis. The LCI of urban land use is smaller than that of water, forest and cropland. Smaller is LCI, stronger the intensity of urban heat island is. For a special region, LCI will increase gradually per unit area with higher urbanization level. At last, remote sensing scale how to affect UHI time and space character is discussed. The intensity and scope of urban heat island results are different with different remote scale. The intensity and scope using ETM+ are all lager than that using MODIS.