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Abstract:
As anthropogenic forces amplify extreme droughts, understanding their global connections is essential for prediction and mitigation plans to fortify ecosystem and societal resilience. However, traditional methods struggle to effectively capture the complex, nonlinear, and asynchronous spatiotemporal associations among drought events across regions. To address this, we introduced a novel complexity-based approach that constructs a global extreme drought complex network using monthly-scale Standardized Precipitation Evapotranspiration Index (SPEI) data from 1901 to 2021. By applying the Event Synchronization (ES) method and analyzing key network metrics, we revealed the spatiotemporal associations and synchronous propagation pathways of drought events. Our approach identified major global drought source regions (out-degree >667), including northern and southern Africa, western Australia, central Europe, and central Asia, as well as key sink regions (in-degree >863), such as the Tibetan Plateau (TP), Indonesia, central South America, and the Amazon Basin. Using network metrics, we quantified the dominant directions and propagation distances of drought teleconnections across regions, revealing that the average global drought propagation distance exceeds 11,000 km. Regions such as the TP and the Amazon exhibited high betweenness centrality (BC), underscoring their critical roles as hubs in the global drought propagation network. Furthermore, we used the Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) Lagrangian particle transport model to simulate moisture transport pathways from the European drought source region to the TP sink region. By integrating complex network analysis with the Lagrangian transport model, we conducted an in-depth investigation of drought propagation pathways. This dual approach reveals previously unrecognized yet highly consistent physical mechanisms underlying drought occurrence and propagation. These findings offer valuable insights for the development of effective drought mitigation strategies.
