关键词: 城市热岛, 地表温度, 热岛等级, 土地利用格局, 南京市

Abstract: Urban environments have undergone significant changes under the background of rapid urbanization, with pronounced urban heat island (UHI) effect. It is important to understand the UHI and identify their relationships with the land use changes, which can provide reasonable suggestions for alleviating UHI and building an effective ecologically livable city. We used 1 km daily MODIS surface temperature data from 2002 to 2022, 30 m summer Landsat imagery, and land use data to retrieve land surface temperature (LST) using the atmospheric correction method. By incorporating the definition of UHI intensity and employing a mean-standard deviation classification approach, we systematically analyzed the spatiotemporal variations of UHI in Nanjing and evaluated the impact of land use patterns on UHI. The results showed that there were significant differences in the spatial distribution of LST, with higher temperatures in urban areas than rural regions. There were significant diurnal differences in LST among different land types, among which the diurnal temperature difference of water body was the most significant. The diurnal and seasonal UHI intensity exhibited significant variations, with the maximum value occurring during day-time in summer (1.52 ℃) and night-time in winter (0.80 ℃). The day-time UHI intensity showed an increasing trend in winter but decreased in summer, while the night-time UHI intensity was increased in all seasons. The areas of UHI steadily increased during 2002-2022, especially for the strong heat island area, which was highly coincident with the urban construction land. The LST in the urban core area was consistent with the normalized building index. The heat island level of grassland and cultivated land was mainly in the middle zone, accounting for 58.0% and 52.8% of their respective land types. Forest and water body were mainly in the cold island zone, accounting for 64.7% and 94.3% of respective land types.

Key words: urban heat island, land surface temperature, heat island level, land use pattern, Nanjing City