Assessing heat risk for residents of complex urban areas from an accessibility-based perspective.

• Introduced an accessibility perspective to assess urban heat risk. • Applied the MSPA analysis method to identify stable heat sources. • Identified the heat risk areas and affected population in different months. • Compared the accessibility measurement method with the traditional method. A heat risk assessment in complex urban areas is important to mitigate the impact of the urban heat island (UHI) and to accurately implement cooling measures. Previous studies have focused on a single 'heat source' or 'resident' oriented assessment method, with fewer assessments and lack of appropriate theoretical approaches that consider both the distribution of residents and heat core areas. This study combined a morphological spatial pattern analysis (MSPA) and a two-step floating catchment area (2SFCA) model to identify UHI patches and heat cores, assessed the accessibility of residents to heat core areas at the neighbourhood scale, and constructed a new framework for assessing the heat risk from an accessibility perspective. A case study of Shenzhen City indicated that the heat core area accounted for 5.5%, 7.8%, 10%, and 7.1% of the whole study area in February, May, August, and November, respectively. The relationship between the areas with a heat risk and UHI patches, and the dominant factors for the formation of different high-risk aggregations had a high spatial heterogeneity. The differences between the accessibility-based assessment results and conventional methods were also discussed, and the heat risk in conventional assessment methods was found to be in error. The accessibility-based heat risk assessment framework can accurately identify heat core areas and high heat risk areas, and provide effective planning guidance for mitigating the negative effects of UHI. [ABSTRACT FROM AUTHOR]