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Abstract:
Hydrological extremes—including pluvials and droughts—pose significant threats to water resources, ecosystems, and societal resilience, underscoring the importance of understanding their global-scale dynamics and drivers. However, the teleconnection patterns between large-scale climate indices (CIs) and hydrological extremes remain insufficiently understood. In this study, we construct an event synchronization climate network using GRACE-derived terrestrial water storage anomalies from August 2002 to December 2023 to identify global synchronization patterns of hydrological extreme events. We then identify synchronization hubs (SHs) where hydrological extremes tend to co-occur across distant locations and investigate the underlying climatic drivers using a recurrence-based synchronization index based on recurrence quantification analysis. Our results show that four dominant CIs influence the hydrological extremes: Niño3.4, North Oscillation Index (NOI), Tropical North Atlantic (TNA), and Arctic Oscillation (AO). Among these, NOI shows the broadest influence, affecting 99.61% of SHs regions associated with wet extremes and 97.99% with dry extremes. Furthermore, the phase-dependent response displays asymmetry: both dry and wet events are primarily linked to the negative phase of Niño3.4, while the positive phase of NOI exerts the strongest overall influence. Wet extremes are similarly impacted by both positive and negative phases of TNA, while dry extremes exhibit a stronger response to the negative phase. These results highlight the value of phase-resolved climate–extreme linkages in advancing our understanding and prediction of global hydrological extremes.
