Study on the change of multi-season urban heat island effect from the perspective of urban functional zones

The Urban Heat Island effect, a climate phenomenon resulting from rapid urban development, significantly impacting urban growth and human health. This study focuses on Nanchang City, Jiangxi Province, China, using Landsat series remote sensing imagery from all four seasons of 2022 to retrieve Land Surface Temperature data for UHI analysis. The study systematically analyzes the spatiotemporal distribution characteristics of Heat Island and influencing factors from the perspective of urban functional zones. Special attention is given to the impact of building form and vegetation cover on the urban thermal environment. Key findings include: (1) Built-up areas contribute most to the heat island effect, but in winter, some built-up areas exhibit cold island phenomena. (2) Except in winter, the Land Surface Temperature of different urban functional zones is ranked from highest to lowest as follows: Industrial Zone, Plastic Playground, Commercial Zone, Low-Rise Residential Zone, High-Rise Residential Zone, and Urban Park. In winter, High-Rise Residential Zone has the lowest temperature. (3) Building height and building height standard deviation are negatively correlated with LST, with the correlation being strongest in winter. (4) The cooling effect of vegetation cover on Land Surface Temperature is particularly significant in Low-rise residential Zones. In summer, when the greening rate increases from 0 to 10% to over 50%, LST in High-Rise Residential Zone decreases by 2.253 degrees C and by 4.02 degrees C in Low-Rise Residential Zone. The study suggests that increasing the greenery in residential areas, optimizing building layout and form, can mitigate the heat island effect and improve urban thermal environments.