How do morphology factors affect urban heat island intensity? an approach of local climate zones in a fast-growing small city, Yangling, China

Abstract

Urban form has been confirmed to be a contributor to the Urban Heat Island (UHI) effect in metropolitan areas, but few studies have focused the relationship in fast-growing small cities through LCZs approach. How the Local Climate Zones (LCZs) distributes and whether the correlations between UHI intensity (UHII) and urban form differ between small cites and large cities remain to be studied. This study mapped LCZs and analyzed UHII in Yangling, a small city in China using the GIS-based method. The results showed: (1) 37 % of the study area contained “High” and “Very High” UHII, mainly in areas with high building density and expansive impervious surfaces. The maximum UHII in Yangling was below 40 °C, which was lower than that of many large cities. In addition, the high UHII areas scattered and formed a small-scale cluster in Yangling, which was different from large cities where high UHII formed large-scale agglomeration areas. (2) Unlike previous findings in megacities, the open Low-rise (LCZ6) was the most prevalent LCZ in Yangling. (3) The UHII of build-up LCZs (2.01 °C) was significantly higher than those of natural LCZ types (-0.61 °C), and the UHII of compact LCZs (LCZ1-3) was higher than that of open LCZs (LCZ4-6). (4) Natural factors were negatively correlated with UHII, whereas most build-up factors were positively correlated with UHII, and the effect of natural factors on UHII was greater than that of build-up factors. These findings will help urban climate researchers and planners better understand the relationship between urban form and UHII and apply this knowledge to build a more comfortable urban thermal environment.

Keywords

• Local climate zone (LCZ)
• Urban Heat Island Intensity (UHII)
• Urban canopy parameters (UCPs)
• Small city
• Yangling