基于DMSP-OLS和珞珈一号夜光遥感影像的粤港澳大湾区城市空间格局演变

Evolution of urban spatial pattern of GBA based on DMSP-OLS and LJ-1 nighttime light remote sensing images

夜光遥感影像数据可有效反映城市空间格局变化。本文基于1992—2012年的DSMP-OLS夜光遥感影像和2018年的珞珈一号遥感影像,利用分层阈值法提取粤港澳大湾区内各城市建成区;通过计算平均灯光强度、平均灯光增长速率、城市建成区面积、城市建成区增长速率、城市重心、城市重心偏移距离等一系列指数,揭示区内各城市的空间格局演变过程。研究结果表明:①1992—2018年,粤港澳大湾区的城市规模大幅增长,沿珠江口两侧形成了以澳门、广州、深圳和香港为核心的倒“U”形城市群,并呈辐射状向周边扩张。②以珠江口为界,粤港澳大湾区东部各个城市的发展水平整体高于西部各个城市,广州、深圳、香港等核心城市发展水平明显高于江门、肇庆、惠州等外围城市。③1992—2018年,粤港澳大湾区建成区的增长速率由小变大,最后逐渐趋于稳定,2002—2007年是城市扩张最迅猛时期。④1992—2018年,粤港澳大湾区的各城市重心迁移方式表现为3种类型:持续向区域中心迁移;持续向相邻城市邻接区迁移;持续向海洋方向迁移。大部分城市的重心迁移方向呈“震荡”特征。

Nighttime light remote sensing images can be effectively used to extract evolution of urban spatial pattern.In this paper,the DSMP-OLS nighttime light(NTL)images from 1992 to 2012 and the LJ-1 NTL images in 2018 are used to extract urban built-up areas of Guangdong-Hong Kong-Macao greater bay area(GBA)by applying dynamic threshold method.On this basis,in order to reveal the spatial pattern and urban expansion process of each city in GBA,a number of indicators are used,including average light brightness,growth rate of average light brightness,urban built-up area,growth rate of urban built-up area,urban center of gravity coordinates,and offset distance of urban center of gravity.Finally,we analyze the main driving factors of urban expansion in GBA combined with the national economic statistics.The results show that:①From 1992 to 2018,the urban scale of GBA increased significantly.It forms an inverted“U”shaped urban agglomeration,with Guangzhou,Shenzhen and Hong Kong as the center,expanding outward in a radial manner.②Taking the Pearl River Estuary as the boundary,the development level of eastern cities is significantly higher than that of western cities.The development level of core cities such as Guangzhou,Shenzhen and Hong Kong were significantly higher than that of peripheral cities such as Jiangmen,Zhaoqing and Huizhou.③From 1992 to 2018,the expansion speed of the built-up area in GBA increases from small to large,and then decreased gradually.2002—2007 was the fastest period of urban expansion.④From 1992 to 2018,there were three types of urban center of gravity migration:the center of gravity of periphery cities continued to move to the center of GBA,the center of gravity of central cities moved to the junction of neighboring cities,the center of gravity of special administrative cities is moving towards the ocean.Most cities have“vibration”in their directions of urban gravity movement.