Mapping and connectivity analysis of thermal comfort zones in Shanghai using a modified temperature–humidity index

In the context of sustained global warming and rapid urbanization, extreme summer heat and humidity increasingly intensify urban heat stress in metropolitan environments. This study develops a remote-sensing–based framework to generate city-scale screening maps of relative hot–humid exposure in Shanghai (summer 2022) using a modified temperature–humidity index (MTHI). The resulting surface is further translated into structural and connectivity-based spatial indicators through morphological spatial pattern analysis (MSPA) and circuit-theory modeling. Areas classified as thermal-comfort zones (i.e., relatively lower hot–humid exposure under the MTHI framework) accounted for 71.3% of the urban area, representing spatial contrasts in thermal–humidity conditions rather than absolute physiological comfort. MSPA and circuit-based analyses revealed a structured, network-like organization of these relative cooling-favorable areas, characterized by a core–edge backbone consisting of 13 source areas, 17 potential corridors, and 39 pinch-point locations. These elements highlight how a limited number of structural features may influence the spatial continuity of cooling-favorable conditions across the city. The proposed framework provides hypothesis-generating spatial indicators of thermal-comfort organization by integrating relative exposure mapping with connectivity analysis using publicly available data and standardized workflows. This approach offers an exploratory planning-support tool that can assist preliminary screening of cooling-sensitive areas in hot–humid cities, while requiring further validation before operational decision-making.