全球疫情下的中国内地航空网络对外连通性

新冠肺炎疫情给世界航空网络的连通性造成重大影响，网络的通达程度明显降低。为了研究中国内地的航空网络对外连通性在疫情影响下的变化，提出对外连通效率这一评价指标，并根据国内外疫情爆发不同阶段的特点采用不同的链路删除规则进行分析。研究结果表明：在疫情爆发前期，因许多国家对中国内地旅客采取入境限制措施，中国内地的航空网络对外连通效率与疫情前相比下降率最大达到39.8%，同等情形下，禁止入境措施对中国内地的对外连通性影响比停飞直航大将近一个数量级，而这两种限制措施造成的影响在不同国家间的横向差异性也巨大。此外，一些与中国内地不存在直航的国家如果采取限制入境措施，也会对中国内地的对外连通性产生很大影响。在疫情爆发中后期，全球的航线连接缩减并未对中国内地的航空对外连通性产生明显影响，中国国际航线间的连通替代关系大大提升了航空网络在此类极端情形下的鲁棒性。

External connectivity of Mainland China's air transport network in COVID-19 pandemic

The COVID-19 pandemic has had a significant impact on the connectivity of the worldwide air transport network, and the accessibility of the network has been largely reduced. To study the variation in the external connectivity of Mainland China's air transport network under the influence of COVID-19, an evaluation metric named Weighted Domestic-Foreign Efficiency (WDFE) is proposed, and different link deletion principles are used to model the characteristics at different stages of the COVID-19 outbreak. It is found that in the early stage of the outbreak, Mainland China's WDFE dropped by nearly 39.8% compared to normal periods due to the entry restrictions adopted by many countries. The entry ban has a larger impact on Mainland China's external connectivity than the suspension of direct flights does, and the impact of these two restrictions is significantly different in various countries. In addition, some countries having no direct flights with Mainland China will also have a considerable impact on Mainland China's external connectivity if they take entry measures. In the mid-late period of the outbreak, the reduction of global flight connections has no major impact on Mainland China's external connectivity. The alternative relationship between Mainland China's external connections has dramatically improved the robustness of Mainland China's air transport network.