Climatic aridity modulates the spatial variations in the responses of terrestrial water budget terms to El Niño–Southern Oscillation

Abstract The El Niño–Southern Oscillation (ENSO) triggers precipitation anomalies, which are not evenly distributed across other terrestrial water budget terms, including runoff, evapotranspiration (ET), and terrestrial water storage change (TWSC). This uneven distribution represents a significant knowledge gap. This study addresses this gap by examining the varied responses of these terms to ENSO events across regions of the continental United States where precipitation is significantly influenced. The results highlight distinct patterns that are contingent upon the regional climatic aridity. In more humid regions, ENSO’s impact is primarily evident in runoff dynamics. As aridity levels escalate, the sensitivity of runoff to ENSO diminishes, while the responses of ET and TWSC become more pronounced. In the driest regions, TWSC exhibits the most significant response to ENSO events. These findings underscore the context-dependent nature of ENSO’s hydrological impacts, which is crucial for predicting water resources using the ENSO indices.