Assessing the effects of land use spatial structure on urban heatislands using HJ-1B remote sensing imagery in Wuhan, China

Urban heat islands (UHIs) have attracted attention around the world because they profoundly affectbiological diversity and human life. Assessing the effects of the spatial structure of land use on UHIs isessential to better understanding and improving the ecological consequences of urbanization. This paperpresents the radius fractal dimension to quantify the spatial variation of different land use types aroundthe hot centers. By integrating remote sensing images from the newly launched HJ-1B satellite system,vegetation indexes, landscape metrics and fractal dimension, the effects of land use patterns on the urbanthermal environment in Wuhan were comprehensively explored. The vegetation indexes and landscapemetrics of the HJ-1B and other remote sensing satellites were compared and analyzed to validate theperformance of the HJ-1B. The results have showed that land surface temperature (LST) is negativelyrelated to only positive normalized difference vegetation index (NDVI) but to Fv across the entire rangeof values, which indicates that fractional vegetation (Fv) is an appropriate predictor of LST more than NDVIin forest areas. Furthermore, the mean LST is highly correlated with four class-based metrics and threelandscape-based metrics, which suggests that the landscape composition and the spatial configurationboth influence UHIs. All of them demonstrate that the HJ-1B satellite has a comparable capacity for UHIstudies as other commonly used remote sensing satellites. The results of the fractal analysis show thatthe density of built-up areas sharply decreases from the hot centers to the edges of these areas, whilethe densities of water, forest and cropland increase. These relationships reveal that water, like forestand cropland, has a significant effect in mitigating UHIs in Wuhan due to its large spatial extent andhomogeneous spatial distribution. These findings not only confirm the applicability and effectiveness ofthe HJ-1B satellite system for studying UHIs but also reveal the impacts of the spatial structure of landuse on UHIs, which is helpful for improving the planning and management of the urban environment.