El Niño‐Southern Oscillation Drives Interannual Extremes of Surface Salinity in the Red Sea

Abstract Salinity plays a fundamental role in shaping ocean circulation, the hydrological cycle, and marine ecosystems at both regional and global scales. Despite being one of the saltiest seas on Earth, the Red Sea (RS) remains poorly understood with respect to its salinity variability and underlying drivers. Using a high‐resolution, well‐validated historical simulation, we show that the El Niño‐Southern Oscillation (ENSO) drives interannual extremes of sea surface salinity (SSS) in the RS. Analysis reveals that ENSO primarily triggers wind anomalies over the RS in October through two complementary atmospheric teleconnections: (a) a tropical pathway involving Walker circulation adjustments that generate sea level pressure (SLP) anomalies over the tropical Indian Ocean, and (b) an extratropical pathway in which Rossby wave trains produce opposing SLP anomalies over the Mediterranean. The resulting SLP gradient drives anomalous winds over the RS, which regulate the advection of low‐salinity Gulf of Aden Surface Water and generate a north‐south dipole during evaporation. These processes jointly drive pronounced SSS variability across the basin. ENSO‐driven SSS extremes alter stratification and deep‐water formation in the RS, with important implications for regional circulation and marine ecosystems adapted to hypersaline conditions. This study identifies October as a critical month for ENSO‐RS teleconnection and highlights the importance of monthly scale analyses for understanding ENSO impacts on regional ocean processes.