Toward Regional Resilience: Multi-Scale Climate Variability and Atmospheric Teleconnections in Hunan, China

The mechanisms by which the regional hydroclimate responds to global climate forcing are complex, particularly in geographically heterogeneous countries like China. Focusing on Hunan Province, this study employs the Standardized Precipitation Index (SPI) derived from long-term precipitation records at 87 meteorological stations to delineate climatic sub-regions with coherent dry–wet variability. Using rotated empirical orthogonal function analysis, we systematically characterize the spatiotemporal patterns of SPI components and quantify their teleconnections with global ocean–atmosphere circulation modes. The analysis of multi-timescale SPI reveals four distinct sub-regions and a pronounced northwest–southeast dipole in long-term trends. Despite an overall reduction in annual drought, the northwestern sub-region experienced intensification. Seasonally, a pattern of spring/autumn drying versus summer/winter wetting emerged. Wavelet analysis identified dominant interannual (2–7 years) and interdecadal (13–71 months) oscillations. These periodicities are significantly teleconnected to large-scale circulation indices (e.g., Southern Oscillation and Pacific Decadal Oscillation), with influences peaking at 16–64-month and 2–5-year scales. Importantly, the primary circulating driver differs by sub-region, revealing a complex teleconnection landscape. The findings delineate region-specific atmospheric pathways, offering insights to bolster drought preparedness and optimize water allocation, thereby enhancing climate resilience in vulnerable monsoon transition zones.