The worldwide air transportation network: Anomalous centrality, community structure, and cities' global roles

TL;DR

This paper explores the global air transportation network's structure, revealing scale-free small-world properties, anomalous centrality patterns, and complex community structures influenced by geopolitical factors.

Contribution

It uncovers the multi-community structure of the network and introduces a method to identify cities' global roles based on their connectivity patterns.

Findings

The network is scale-free and small-world.

Most connected cities are not the most central.

Community structure is influenced by geopolitical factors.

Abstract

We analyze the global structure of the world-wide air transportation network, a critical infrastructure with an enormous impact on local, national, and international economies. We find that the world-wide air transportation network is a scale-free small-world network. In contrast to the prediction of scale-free network models, however, we find that the most connected cities are not necessarily the most central, resulting in anomalous values of the centrality. We demonstrate that these anomalies arise because of the multi-community structure of the network. We identify the communities in the air transportation network and show that the community structure cannot be explained solely based on geographical constraints, and that geo-political considerations have to be taken into account. We identify each city's global role based on its pattern of inter- and intra-community connections, which enables us to obtain scale-specific representations of the network.