In the past few decades, thousands of satellites have been launched into space for various purposes. Some satellites take images of the Earth, some improve GPS systems, and others carry scientific instruments like Synthetic Aperture Radar (SAR). SAR satellites emit radar pulses and measure the reflection or backscatter, which depends on physical properties such as height and roughness. Unlike other satellites, SAR works well in any weather conditions, making it a valuable tool for research.
However, SAR data has its limitations, including signal noise and image distortion. Urban studies, in particular, have struggled to access long-term and high-resolution backscatter data. Most urban monitoring relies on optical images, which provide clear two-dimensional views but lack three-dimensional aspects essential for comprehensive analysis. To address this gap, researchers from China Agricultural University combined SAR and optical data to reconstruct long-term backscatter coefficient data in Chinese cities.
The study focused on the Jing-Jin-Ji (JJJ) region, which includes major cities like Beijing and Tianjin. By analyzing data from 1990 to 2022, researchers were able to track urban growth and changes accurately. The approach revealed significant vertical expansion in Beijing’s urban core, particularly in districts like Haidian and Chaoyang. On the other hand, cities like Cangzhou showed slower growth rates, highlighting diverse urbanization patterns within the region.
The research went beyond estimating building heights. It utilized long-term data for urban surface classification and flood monitoring, providing valuable insights for urban planners and policymakers. The ability to capture such data over decades is crucial for understanding urban development trends and addressing environmental challenges.
Looking ahead, researchers aim to expand their approach globally and explore additional urban parameters. By estimating building height and analyzing urban environmental issues like the urban heat island effect and carbon emissions, the research contributes to sustainable development goals. The findings of this study could be instrumental in future urban planning and policy-making efforts.
Overall, the integration of SAR and optical data offers a comprehensive understanding of urban dynamics and paves the way for innovative research in urban studies. The combination of satellite technologies and data analysis techniques opens up new possibilities for monitoring and managing urban growth in an increasingly complex world.
