开展城市群建设用地扩张时空变化特征分析,对优化城市群空间格局、促进区域协调发展具有重要意义。本文以全国19个城市群为研究对象,基于1990~2020年全国中等尺度分辨率的遥感影像数据,进行城市集中建设区提取,并从城市群扩张进程、城市群发展阶段、城市群扩张模式以及城市群重心迁移规律等方面开展了研究。结果发现：1)近30年全国19个城市群城市规模变化曲线总体呈现“S”型,城市群扩张进程大致可分为缓慢扩张、快速扩张和平稳扩张三个时期；东部城市群进入快速扩张期比西部早10年左右；多数城市群在2015年之后进入平稳扩张期。2)至2020年,19个城市群均处于较高级别发展阶段,内部中心城市与外围城市之间的空间扩张协调度不断提高；东部城市群整体处于更高级别的城市群发展阶段。3)基于城市群在不同方向的扩张规模,全国19个城市群的空间扩张模式可以分为环状扩张、扇状扩张、轴状扩张,空间扩张模式与城市群内部核心城市的数量、位置和影响力密切相关。4)从城市群重心位置变化来看,84%的城市群的重心位置在30年间相对稳定,基本位于核心城市或邻近核心城市的同一地市内,城市群的核心城市吸引力强,外围城市建设规模扩张较为平均。长时序、高精度的城市建设规模监测能够全面地反映城市群发展进程与模式,为城市群空间高质量发展规划与决策提供信息支撑与科学依据。

The analysis of spatial and temporal variation characteristics of construction land expansion in urban agglomerations is of great significance for optimizing the spatial pattern of urban agglomerations and promoting regional coordinated development. This work takes 19 urban agglomerations in China as the study area, extracts the urban concentrated construction area using remote sensing image data from 1990 to 2020, and analyzes the urban agglomeration expansion process, urban agglomeration development stage, urban agglomeration expansion mode and urban agglomeration center of gravity migration. The results show that: 1) In the past 30 years, the urban construction land expansion curve of 19 urban agglomerations in China generally presents an S type, and the expansion process can be roughly divided into slow expansion period , rapid expansion period and stable expansion period . The eastern urban agglomerations entered the rapid expansion period about 10 years earlier than the western urban agglomerations. Most urban agglomerations entered a period of steady expansion after 2015. 2) By 2020, the 19 urban agglomerations are in a high-level development stage, and the coordination degree of spatial expansion between internal central cities and peripheral cities is constantly improving. The eastern urban agglomeration is in a higher level of urban agglomeration development stage, comparing with the western ones. 3) Based on the expansion of urban agglomerations in different directions, the spatial expansion modes of 19 urban agglomerations in China can be divided into circular expansion, fan-shaped expansion and axial expansion. The spatial expansion mode is closely related to the quantity, location and influence of core cities within urban agglomerations. 4) The gravity center of urban agglomeration is relatively stable in the past 30 years, basically located in one core or adjacent city. The core city of the urban agglomeration is attractive, and the expansion of the construction of the peripheral city is relatively balance. Long-term and high-precision urban construction area monitoring can effectively explain the development process and mode of urban agglomerations, and also provide scientific information for optimizing the spatial high-quality development planning and decision-making of urban agglomerations.