A satellite perspective of interannual and seasonal variations in greenspace and human exposure over urban and peri-urban areas in Chinese cities from 2000 to 2020

• A spatially and temporally seamless fine-scale vegetation cover dataset was created to quantify the urban greenspace; • During 2000 and 2020, the greenspace in 12 Chinese cities has generally increased, and the greendays slightly extended; • Peri-urban areas have more increases in greenspace and greendays than core urban areas; • Equity in urban greenspace exposure was improved during the past two decades. Urban greenspaces significantly influence the ecological environment, resident health, and sustainable development of cities. Fractional vegetation cover (FVC) is a common measure of urban greenspace, and a long-term FVC dataset is required to characterize the dynamics of vegetation in a complex urban environment along with socioeconomic development. This study proposed a data fusion method to integrate multiple existing satellite-based FVC datasets to create a spatially and temporally seamless FVC dataset at a 30-m resolution, which was applied to urban greenspace mapping for 12 representative cities in China for the 2000–2020 period. In addition, the distribution and changes in the equality of urban greenspaces exposure during the study period were examined by integrating the 30-m FVC datasets with a population-weighted exposure framework. Greendays are defined as the annual duration for which urban residents enjoy greenery throughout the year. The results suggest that greenspace in the 12 cities showed an upward trend, with greendays displaying a slight overall extension. The magnitude of the increase in greenspace and greendays was generally greater in peri -urban areas than in core urban areas. Equality in urban greenspace exposure remained high and improved over time. This research offers essential data support for urban planners and policymakers, contributing to more informed management of urban greenspaces. By mapping the evolution of greenspace exposure, this research supports decision-making towards a more equitable, healthy urban environment, aligning with the United Nations Sustainable Development Goals focused on health, well-being, and sustainable urbanization.