Impact of urban greenspace on the urban thermal environment: A case study of Shenzhen, China

•Diurnal and seasonal urban changes of thermal environment were explored.•LST showed an increasing trend during daytime and nighttime.•Diurnal temperature range (DTR) decreased significantly.•Urban greenspace impact on LST was not always a cooling effect.•Results could help promote healthy and sustainable development of city. Rapid urban expansion has significantly altered the urban surface energy balance, consequently impacting the urban thermal environment. Urban greenspace (UG) plays a crucial role in regulating urban climate. This study utilizes a seamless land surface temperature (LST) dataset to elucidate the spatio-temporal patterns of LST and diurnal temperature range (DTR) in Shenzhen, a rapidly urbanizing city in China, and the influence of UG on urban thermal environment. The UG showed a notable decrease of 16.3 % from 2000 to 2020. Over the past 21 years, both daytime LST (LSTD) and nighttime LST (LSTN) exhibited an upward trend, while DTR showed a significant downward trend, especially in autumn. Significant spatial changes in LSTD, LSTN, and DTR were observed in winter across the entire city. Moreover, our results emphasize that the impact of UG on LSTD displays non-uniform cooling and varies significantly in terms of season, greenspace quality, and geographical location. Our assessment of changes in the urban thermal environment in Shenzhen and the role of UG on LST can offer theoretical support for policymakers in developing effective urban cooling measures and healthy urban development.