Interdecadal Pacific Oscillation Modulates Hydrological Sensitivity Residuals Derived from Energy Budget Decomposition

Hydrological sensitivity, defined as the change in latent heat release per degree of global mean surface temperature increase, is a key metric for understanding future precipitation changes and the global hydrological cycle. Based on the global energy budget, hydrological sensitivity can be decomposed into three components: longwave cooling, shortwave absorption, and sensible heat flux. In this study, we analyzed hydrological sensitivity from 1980 to 2025 using ERA5 reanalysis data. A decomposition of hydrological sensitivity into three energy budget terms reveals a non-negligible residual that cannot be explained by these conventional components alone. Diagnostics of the spatiotemporal characteristics of this residual and its relationship with internal variability show a significant correlation with the Pacific Decadal Oscillation(PDO)/Interdecadal Pacific Oscillation(IPO). At the global scale, variations in precipitation dominate the hydrological sensitivity residual. These findings suggest that hydrological sensitivity is modulated by atmosphere–ocean interactions in the Pacific represented by PDO/IPO. We further examine the physical mechanisms linking internal variability to these residuals.