关键词: 粤港澳大湾区, 城市空间格局演变, 夜光遥感, 城市建成区, 城市重心

Abstract: 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:① From 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. ② Taking 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. ③ From 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. ④ From 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.

Key words: Guangdong-Hong Kong-Macao greater bay area (GBA), evolution of urban spatial pattern, nighttime light remote sensing, urban buildup area, center of urban gravity