Climatic drivers of summer run-of-river hydropower generation in the middle reaches of the Yangtze River Basin: Synergistic effects of subtropical westerly jet dynamics and transregional teleconnections

Based on ERA5 reanalysis and CN05.1 gridded observational datasets, this study investigates key meteorological drivers and cross-seasonal mechanisms influencing summer (June–July–August) run-of-river (ROR) hydropower generation in the middle reaches of the Yangtze River Basin (MYRB). Results reveal synergistic regulation by the meridional displacement of the subtropical westerly jet (SWJ) and Pakistan convective activity through East Asian atmospheric circulation. Southward (northward) SWJ shifts coupled with weakened (intensified) Pakistan convection enhance (reduce) MYRB precipitation while lowering (elevating) temperatures, thereby increasing (decreasing) ROR hydropower generation. Precursor analysis identifies spring negative (positive) sea surface temperature anomalies in the northwestern Indian Ocean may strengthen (weaken) meridional thermal gradients, forcing corresponding SWJ displacements. Concurrently, Central Asian cooling (warming) in spring modifies the Arabian Sea–Central Asia pressure gradient, suppressing (enhancing) South Asian monsoon moisture transport to Pakistan. These oceanic–terrestrial thermal coupling mechanisms demonstrate significant predictability for MYRB hydropower variability.