LAUSR

The urban heat island effect is becoming more and more serious due to the continuous expansion of cities in China, and improving the urban thermal environment is an important prerequisite for creating a livable city. Based on the Landsat TM images of 2001 and 2011 and Landsat TIRS images of 2021, this study investigated the spatial and temporal distribution and evolution characteristics of the urban thermal environment in Lanzhou City in the last 20 years by using the radiation equation conduction method to invert the surface temperature of Lanzhou City. The results show the following: (1) The radiation range of the medium temperature zone in Lanzhou City spreads in an “extended” style from 2001 to 2021 until it covers the whole main urban area, the secondary high and low temperatures decrease, and the corresponding medium temperature zone increases over a large area. (2) The average temperatures of Lanzhou urban area and its arable land, forest, grassland, and water area within the urban area reaches 10–25 °C, and the heat island area decreases by 9.56% in 20 years, with the high-temperature zone decreasing by 42.32%. (3) The proportion of water bodies and the proportion of impermeable surfaces are dominant factors in the spatial differentiation of surface temperature, and the interaction and synergy of various influencing factors affect the spatial differentiation of surface temperature.