How does urban thermal environmental factors impact diurnal cycle of land surface temperature? A multi-dimensional and multi-granularity perspective

Numerous researches have been conducted on the impacts of urban thermal environmental factors on land surface temperature (LST) variations. However, few have comprehensive studied on their diurnal variations. This study explored whether the novel ECOSTRESS LST data can create fresh opportunities for analyzing the diurnal urban thermal environment. Here we utilized ECOSTRESS to explore the relative contribution, marginal effects, and granularity effects of 2D/3D urban factors on diurnal LSTs in a "furnace city" Fuzhou. Our results revealed that: (1) Anthropogenic heat flux and urban blue and green spaces have the greatest influence on nighttime LST and daytime LST, respectively. (2) The impacts of urban factors on diurnal LSTs are nonlinear. The marginal effect curve can reveal the crucial value ranges and turning points of the factors that affect diurnal LSTs. (3) The overall impact of the 2D factors on diurnal LSTs is more significant than that of the 3D factors. Meanwhile, 3D factors are indispensable elements in urban thermal environment research. They serve as an important supplementary to 2D factors in the vertical space of cities. Our findings can identify crucial factors influencing urban thermal environment, providing innovative insights for the development of strategies to mitigate urban heat island effects.