Evolution of urban thermal environment in Hefei, China

Abstract:

Urban heat island (UHI) represents an adverse consequence of urbanization, a major anthropogenic modification to the Earth system, and its relationship with urban development is not well understood, which limit decision makers to make more informed decisions to improve urban environment. We examined the spatiotemporal trends of the land surface temperatures along the urban development intensity (UDI) and urbanization age in Hefei from 2000 to 2019 using data from Aqua MODIS, Landsat TM/ETM+, global artificial impervious area maps, and geospatial analysis techniques. We found that: (1) The urbanization rates of the main urban area and the whole area of Hefei has been increasing; (2) The relationship between urbanization age and land surface temperature actually is the relationship between different land use types and the corresponding land surface temperature, and the relative differences in temperature among built-up areas of different ages remains relative stable in time; (3) The daytime land surface temperatures increase linearly (p < 0.01) with rising UDI for all years from 2000 to 2019; (4) The area of high-temperature area in Hefei keeps expanding from 2000 (administrative region:1282 km²; main urban area:291 km²) to 2019 (administrative region:2826 km²; main urban area:663 km²), and the spatial distribution becomes more dispersed, showing a northwest-southeast distribution pattern. The spatiotemporal distribution of urban thermal environment in Hefei is related to the polycentric urban development strategy and clear designation of different functional areas. The findings in this study shed lights on thermal environmental change in cities whose polycentric urban development is also industrial-based.

Keywords: Urban thermal environment ;Urban expansion ;Spatiotemporal distribution.