The spatio-temporal evolution of urban field strength and pattern of autocorrelation among cities in China

According to GDP(without agriculture) data of all the 661 cities in China,this paper integrates the methods of spatial autocorrelation and urban field strength,and analyzes the space-time evolution of urban field strength and spatial autocorrelation.It is concluded that huge cities such as Beijing and Shanghai,have formed the circle structure of urban influence on the whole country.More mega cities have regional-wide influence,such as Wuhan,Zhengzhou,Chongqing and Chengdu.Many big cities only have local-wide influence,and are forming a multi-center structure.Cities in coastal areas have much greater influences than those in inland areas.Besides,there are significant connections and interactions among cities in large megalopolises.The largest three megalopolises or urban agglomerations,i.e.,Pearl River Delta,Yangtze River Delta and Beijing-Tianjin-Hebei region,have developed rapidly.The regional patterns of urban agglomerations,such as southern Liaoning and Shandong Peninsula,have already emerged.However,there are weaker correlations among the cities in inland areas which are in independent status.Although the patterns of influence of cities in China varied slowly,great changes have taken place.With the booming economy,the regions affected by urban expansion have accelerated the development of related urban agglomerations.