Studying the generation and development of urban areas is of great significance to improve our understanding of urbanization. However, it is still difficult to explore the spatial-temporal dynamic characteristics of urban agglomeration in the global scope. The easily accessible night-time light (NTL) data provide a window to observe the progress of human urban development from space. This study proposes a method based on NTL-Internet data. By combining the NTL center of gravity and the interregional link index model, it is used to detect the spatial expansion characteristics of the Yangtze river delta urban agglomeration (YRDUA), thus completing the comprehensive exploration of the urbanization in YRDUA. Results demonstrate that YRDUA, compared with the five major urban agglomerations in Europe, North America, and Asia, maintains the greatest urbanization potential. Further analysis shows that the urban area of Hefei has a huge development momentum. In addition, the urbanization level of YRDUA is easily affected by national planning, which conforms to the model of urban expansion, including infilling, edge expansion, and leapfrogging in different metropolitan areas. Finally, the link index model based on Internet data is utilized to quantitatively calculate the relevance of various cities in YRDUA. The results not only confirm the findings based on the NTL data but also explain that those metropolitan areas play a complementary and indivisible role in the urbanization process of YRDUA. This study will provide a framework for other research works to assess the spatial-temporal changes in urban characteristics, which is beyond the scope of a single city.

中文翻译：

---

基于夜光遥感技术探索长三角城市群时空动态

研究城市地区的产生和发展，对于提高我们对城市化的认识具有重要意义。然而，在全球范围内探索城市群的时空动态特征仍然很困难。易于获取的夜间灯光（NTL）数据为从空间观察人类城市发展进程提供了一个窗口。本研究提出了一种基于 NTL-Internet 数据的方法。结合NTL重心和区域间联系指数模型，检测长三角城市群（YRDUA）的空间扩展特征，完成对YRDUA城市化的综合探索。结果表明，与欧洲、北美和亚洲的五个主要城市群相比，YRDUA 保持着最大的城市化潜力。进一步分析表明，合肥市区发展势头强劲。此外，长三角城市化水平易受国家规划影响，符合城市扩张模式，包括不同都市圈的填充、边缘扩张和跨越。最后，利用基于互联网数据的链接指数模型，定量计算长三角各城市的相关性。结果不仅证实了基于 NTL 数据的发现，而且也说明了这些大都市区在 YRDUA 的城市化过程中起着互补和不可分割的作用。本研究将为其他研究工作提供一个框架，以评估城市特征的时空变化，这超出了单个城市的范围。