Study on the Synergistic Mechanisms of Daytime and Nighttime Heatwaves in China Based on Complex Networks

Abstract With the ongoing rise in temperatures across China, the frequency of heatwaves has been increasing. Understanding the evolution and underlying mechanisms of these events is essential for addressing climate change and developing adaptive strategies. In this study, we apply complex network theory to construct heatwave complex networks, enabling an examination of its topological characteristics and structural changes before and after abrupt shifts in heatwave occurrence. The results reveal pronounced spatial heterogeneity, with hotspots in the south, northwest, and Middle and Lower reaches of Yangtze River regions, the latter being the most prominent. Network analysis indicates low centrality in the Yangtze River region, suggesting the dominance of local drivers, whereas the north exhibits high centrality, reflecting large-scale systemic influences. A Two-Layer network further uncovers spatiotemporal coupling between daytime and nighttime heatwaves. After 1993, northern network centrality and clustering have increased particularly in the northeast indicating strengthened regional synergy, while the Yangtze River region has remained relatively stable. The daytime heatwave network demonstrates structural resilience to climatic shifts. This network-based framework provides a novel perspective for investigating the interdecadal dynamics of heatwaves.