Feng, Xinyuan , Wang, Ying , Wang, Yixing , Wang, Jianshun , Liu, Xiaoli , Liu, Fei
2025-11-06 THEORETICAL AND APPLIED CLIMATOLOGY 2025 156(卷), 11(期), (null页)
To investigate the spatiotemporal evolution and driving mechanisms of compound dry and hot events (CDHEs) in the Yellow River Basin under global climate warming, this study developed a CDHE index based on meteorological observations and reanalysis data from June to October for the period 1960-2023. Based on correlation analysis, random forest regression, and principal component analysis (PCA), five key meteorological variables were identified across six climatic subregions (A-F): Normalized Difference Vegetation Index (NDVI), Surface sensible heat flux (SSHF), Potential evaporation (PET), Skin reservoir content (SRC), and Volumetric soil water layer 1 (VSWL1). The results show that: (1) High-frequency CDHEs zones exhibit significant spatial clustering, with the central Loess Plateau and the Guanzhong Plain emerging as hotspots-particularly for high-intensity events at levels L4 and L5. The frequency of L4-L5 CDHEs has increased significantly at rates of 3.03% and 4.72% per decade, respectively. (2) The Mann-Kendall test identified 1996 as a climatic mutation point. Following this shift, the frequency of extreme CDHEs increased from 4.67% to 11.59%, while their spatial coverage expanded from 20% to 43%. These results suggest that climate warming has substantially intensified both the severity and spatial reach of CDHEs. (3) PCA results indicate that CDHEs are primarily driven by positive land-atmosphere feedbacks. Due to spatial heterogeneity in hydrothermal conditions, both the triggering thresholds and feedback intensities vary considerably across climatic zones, resulting in regionally distinct patterns of CDHEs occurrence. Overall, the dominant driving mechanisms exhibit a downstream evolution from energy-dominated in the upper reaches, to hydrothermal-dominated in the middle reaches, and finally to moisture-dominated in the lower basin.