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 (CT) 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.