Hierarchical structure and distribution pattern of Chinese urban system based on aviation network
基于航空网络的中国城市体系等级结构与分布格局

The air transportation has become an important conveyance to carry passengers and cargos, and an important factor to influence the regional urban system. The status of a city in the global or national aviation network directly reflects the hierarchy of the city in the global or national urban system. The aviation network which is comprised of nodes (airports) and lines (airlines) represents the spatial accessibility of the cities, and intuitionisticly reflects the hierarchical structure and distribution pattern of the national urban system. This article collects the airline data which include 128 cities open to air traffic and 2083 airlines from China's 14 major airline companies. The correlation analysis proves that in the aviation network the number of urban airlines was positively correlative to the size of the urban population. On this basis, through the aviation network analysis based on the airline network map of Chinese cities, the article uses the methods of charts discriminance and the clustering analysis to classify all the 128 cities into four hierarchies. They are national central cities which include three cities, regional central cities which include seven cities, sub-regional central cities which include 31 cities and general local central cities which include 87 cities. Then,from a unique perspective of aviation network the article reveals the characteristics of the hierarchical structure and distribution pattern of Chinese urban system under the open conditions, including:1) the urban hierarchical system takes on a typical pyramidal structure, which means the higher the hierarchy of the cities in the system, the smaller the number of cities; 2) the administrative, economic and tourism factors affect the aviation network markedly, consequently affect the urban hierarchical system strongly; 3) the distribution of Chinese cities has obvious differences between east and west, which means the higher-hierarchical cities are mainly distribute in the east, and the aviation relation of the west cities is mostly eastward; 4)the three national central cities including Beijing, Shanghai and Guangzhou and the seven regional central cities including Shenzhen, Urumqi, Shenyang, Chengdu, Xi'an, Chongqing and Kunming constitute the foundamental framework of Chinese urban aviation network, and they are the core of the Chinese urban system. The lower hierarchical cities join in the national aviation network through connecting with the higher hierarchical cities, and in this way they become part of the Chinese urban system.