Mapping Global Built-Up Height Dynamics Using Temporally Calibrated Time Series Radar Data

Understanding the dynamics of global built-up heights is crucial for fostering sustainable urban development and to manage urban environments effectively. While prior studies have leveraged satellite data to map built-up heights, study exploring their dynamics over extended time frames at a global scale is limited. To address this gap, we utilized radar time series data to analyze global built-up height dynamics. Initially, we calibrated radar data from multiple sources to prepare a temporally consistent dataset. Subsequently, we estimated annual built-up heights and volumes from 1995 to 2018 at a global scale (5.5-km resolution) using an enhanced built-up height estimation model. Our results indicated that the estimated built-up heights, ranging from 0 to 6.5 m, closely correlate with reference datasets, demonstrating a root mean square error of 0.32 m and an R 2 value of 0.69. By 2018, the global built-up volume had reached 931.17 km 3 , nearly 2.4 times greater than 273.09 km 3 of 1995. Notably, the relative growth rate of built-up volume in the Global South is approximately double that of the Global North. By shifting the focus from traditional horizontal urban expansion to vertical built-up volume growth, this study provided deeper insights into urban evolution. This approach not only aids in the development of urban growth models but also enhances research on energy consumption and carbon emissions.