Uncertainties of Urban Heat Island Estimation With Diverse Reference Delineation Methods Based on Urban–Rural Division and Local Climate Zone

Abstract

The precise quantification of surface urban heat island intensity (SUHII) is fundamental for understanding the process, causes, and solutions to thermal environmental change. However, the existing methods for SUHII estimation are not uniform in nonurban reference selection, with inconsistent consideration of relevant influencing factors. The associated uncertainty can be further exacerbated under seasonal fluctuations of atmospheric and surface environments. This study concentrated on macrocity and intraurban local scales to examine the variations in SUHII assessment and its seasonal changes using different reference delineation methods. City-scale analysis included eight references based on the fixed areas or dynamic buffers, while local-scale analysis took six natural cover types as references under the local climate zone (LCZ) framework, respectively. Results revealed significant differences in SUHII using diverse references, and the inconsistency varied across seasons. On the city scale, the most pronounced intermethod difference occurred in winter, while stronger consistency of spatial patterns was observed in summer. Relatively, higher seasonal SUHIIs and stronger spatial variabilities were generated by methods using fixed areas. On the local scale, a strong consistency of spatial patterns was also observed in summer, while the most pronounced difference occurred in spring. Maximum local SUHIIs in all seasons were obtained using LCZ G as a reference. The study further summarized a list of criteria of reference selection for both scales. Overall, this study provides empirical evidence supporting the appropriate reference delineation for reliable SUHII estimate, especially for seasonal analysis. It can facilitate an improved understanding of urban thermal variations and benefit effective urban heat mitigation.