Abstract: Alleviating urban thermal environment effect and adjusting urban landscape layout are crucial for improving human settlement comfort and promoting sustainable urban development. Based on multiple Landsat 8 remote sensing data of the main urban area of Xi’an, Shaanxi Province, we explored the spatiotemporal variations of land surface temperature (LST) with the mean-standard deviation and regional analysis methods. Combined with the local climate zone (LCZ) theory, the contribution index was used to quantitatively analyze the influence of 17 LCZs on urban heat island effect, and Cplex solver was utilized to optimize LCZs. The results showed that: (1) The heat island effect exhibited distinct spatial heterogeneity and seasonal variations. In spring, the thermal landscape pattern showed a patchy distribution. In summer, the heat island spatial agglomeration effect was enhanced significantly. There was a "dual core" model in autumn and a unique “cold center and hot periphery” structure in winter. (2) LCZs of built-up area generally had higher LST than natural areas, especially LCZ2 (compact midrise) and LCZ8 (large low-rise). Natural areas such as LCZ11 (dense forest) and LCZ12 (sparse forest) had the lowest LST. LCZ2, LCZ5 (open midrise) and LCZ8 all showed high thermal contribution in spring, summer, and autumn. LCZ17 (water) exhibited the significant cold contribution, and LCZ14 demonstrated the most prominent fractional vegetation cover (FVC) contribution. LCZ1 (compact highrise), LCZ2 and LCZ4 (open high-rise) constituted the primary population agglomeration areas, while LCZ5 stood out in both FVC and population density contribution. (3) After optimization, the areas of LCZ2, LCZ11, LCZ12, and LCZ17 increased by 13.5 to 119.2 km², and those of LCZ3, LCZ5, LCZ7, and LCZ8 decreased by 5.2 to 259.9 km². LST declined from 39.94 to 38.81 ℃. To promote sustainable urban development, the areas of LCZ5 and LCZ8 should be constrained, while those of LCZ11 and LCZ17 should be increased.

Key words: urban heat island, WUDAPT, local climate zone, Cplex solver, sustainable development