Remote sensing of diverse urban environments: From the single city to multiple cities

Remote sensing of urban environments has unveiled a significant shift from single-city investigations to the inclusion of multiple cities. Originated from the ideas of the Remote Sensing of Environment special issue entitled "Remote Sensing of the Urban Environment: Beyond the Single City," this paper offers a comprehensive examination of the state of the science in multi-city remote sensing, and aims at fostering the rapid advancement of this emerging field to address global sustainability challenges and support knowledge development needed for a new discipline - urban sustainability science (USS). Through a synthesized review of eight key research fields within urban remote sensing [i.e., land use and land cover (LULC) and change, urban vertical structure, urban heat islands, hazards, energy use and emissions, air quality, carbon budgets, and green space], the paper provides insights into the underlying rationale for conducting multi-city studies, the criteria employed in the selection of cities, the societal applications, as well as the opportunities and future directions for expanding the scope of assessments in multi-city remote sensing.