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<p>Complex network analysis based on event synchronization has emerged as a powerful tool for detecting concurrent extreme hydroclimatic events across the globe. While synchronization patterns of homogeneous extreme events are well-established, the spatiotemporal characteristics of heterogeneous event synchronization, particularly the interplay between dry and wet extremes, remain poorly understood. Here, we develop type-dependent climate networks to systematically investigate global synchronization patterns of both heterogeneous (Dry–Wet, Wet-Dry) and homogeneous (Dry-Dry, Wet-Wet) extreme events. Quantitative analysis using two independent precipitation datasets demonstrates that tropical regions emerge as dominant nodes with the highest network connectivity in the global synchronization pattern. The spatial topology reveals fundamentally different synchronization patterns: homogeneous events exhibit a characteristic bimodal distribution peaking at both regional (≤ 2500 km) and long-range scales (5000–15000 km), whereas heterogeneous synchronization is characterized by a single dominant peak at long-distance connections (5000–15000&#xa0;km), indicating preferential large-scale coupling between opposing extremes. Through constructing ocean-land climate networks, we identify the tropical western Pacific (WP) as the dominant teleconnection hub, exhibiting significantly stronger connectivity with global land regions compared to other tropical ocean basins. During WP drought episodes, wet anomalies manifest in southern China and the western United States, while droughts emerge in eastern Siberia and northeastern South America. Conversely, WP wet periods trigger droughts across the Middle East and central-eastern Africa, concurrent with wet conditions in Australia and southern Africa. These synchronization patterns are mechanistically linked to anomalous atmospheric circulation, as confirmed by 500&#xa0;hPa geopotential height composite analysis. Furthermore, WP-related teleconnections show pronounced temporal evolution under climate change, characterized by asymmetric trends between dry and wet periods. WP drought-related teleconnections have significantly weakened since 2000, while wet-related teleconnections have intensified. This asymmetric response is primarily driven by background sea surface temperature warming in the WP, which enhances convective precipitation while inhibiting drought development. Ocean-forced atmospheric general circulation model experiments from CMIP6 successfully reproduce both the observed synchronization patterns and their contrasting trends, validating the ocean's regulatory role in these teleconnections. Our findings provide insights into global hydroclimate connectivity and highlight the crucial role of the tropical western Pacific in modulating extreme event synchronization patterns.</p>

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Global teleconnection of concurrent dry and wet events revealed by climate network

  • 期刊论文

  • 发表日期：

    2025年6月12日

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  • Menghao Dong,
  • Cheng Sun,
  • Wei Lou,
  • Linfeng Shi,
  • Zichen Song,
  • Yihua He,
  • Yibing Tong

摘要

Complex network analysis based on event synchronization has emerged as a powerful tool for detecting concurrent extreme hydroclimatic events across the globe. While synchronization patterns of homogeneous extreme events are well-established, the spatiotemporal characteristics of heterogeneous event synchronization, particularly the interplay between dry and wet extremes, remain poorly understood. Here, we develop type-dependent climate networks to systematically investigate global synchronization patterns of both heterogeneous (Dry–Wet, Wet-Dry) and homogeneous (Dry-Dry, Wet-Wet) extreme events. Quantitative analysis using two independent precipitation datasets demonstrates that tropical regions emerge as dominant nodes with the highest network connectivity in the global synchronization pattern. The spatial topology reveals fundamentally different synchronization patterns: homogeneous events exhibit a characteristic bimodal distribution peaking at both regional (≤ 2500 km) and long-range scales (5000–15000 km), whereas heterogeneous synchronization is characterized by a single dominant peak at long-distance connections (5000–15000 km), indicating preferential large-scale coupling between opposing extremes. Through constructing ocean-land climate networks, we identify the tropical western Pacific (WP) as the dominant teleconnection hub, exhibiting significantly stronger connectivity with global land regions compared to other tropical ocean basins. During WP drought episodes, wet anomalies manifest in southern China and the western United States, while droughts emerge in eastern Siberia and northeastern South America. Conversely, WP wet periods trigger droughts across the Middle East and central-eastern Africa, concurrent with wet conditions in Australia and southern Africa. These synchronization patterns are mechanistically linked to anomalous atmospheric circulation, as confirmed by 500 hPa geopotential height composite analysis. Furthermore, WP-related teleconnections show pronounced temporal evolution under climate change, characterized by asymmetric trends between dry and wet periods. WP drought-related teleconnections have significantly weakened since 2000, while wet-related teleconnections have intensified. This asymmetric response is primarily driven by background sea surface temperature warming in the WP, which enhances convective precipitation while inhibiting drought development. Ocean-forced atmospheric general circulation model experiments from CMIP6 successfully reproduce both the observed synchronization patterns and their contrasting trends, validating the ocean's regulatory role in these teleconnections. Our findings provide insights into global hydroclimate connectivity and highlight the crucial role of the tropical western Pacific in modulating extreme event synchronization patterns.