Linking salinity and precipitation through moisture transport: a study for the North Atlantic

Abstract

Sea surface salinity (SSS) is a key indicator of the ocean–atmosphere freshwater balance and plays a central role in global moisture transport. This study investigates how extreme SSS anomalies in the subtropical North Atlantic (NATL) source region influence atmospheric moisture pathways and precipitation in surrounding continental and island sink regions. Monthly SSS data (1985–2014) from the EN4.2.2 dataset were combined with high-resolution Lagrangian moisture tracking via FLEXPART-WRF simulations. Extreme salinity events (±1σ, ≥2 consecutive months) were identified and linked to composite anomalies of evaporation, vertically integrated vapor transport (IVT), mean sea-level pressure, geopotential height, and vertical velocity. Our results show that high-salinity episodes, driven by prolonged evaporation and anticyclonic regimes, enhance westward moisture export to the Caribbean and Central America. Conversely, low-salinity events coincide with cyclonic anomalies that redirect moisture toward southwestern Europe, notably the Iberian Peninsula and Madeira. Precipitation responses in island regions were more heterogeneous, reflecting their proximity to the source. A significant lagged correlation with the ONI index suggests ENSO’s influence on NATL salinity variability. These findings demonstrate that SSS anomalies can serve as diagnostic signals—and potential predictors—of regional hydrological changes, offering new insights for medium-range precipitation forecasting.