Global Search for Autumn-Lead Sea Surface Salinity Predictors of Winter Precipitation in Southwestern United States

Abstract

Sea surface salinity (SSS) is sensitive to changes in ocean evaporation and precipitation, that is, to changes in the oceanic water cycle. Through the close connection between the oceanic and terrestrial water cycle, SSS can be used as an indicator of rainfall on land. Here we search globally for teleconnections between autumn-lead September-October-November SSS signals and winter December-January-February precipitation over southwestern United States. The SSS-based model (R2 = 0.61) outperforms the sea surface temperature-based model (R2 = 0.54). Further, a fresh tropical Pacific in autumn, indicated by low SSS, corresponds with wet winters. Recent studies suggest that anomalously high rainfall in the tropics may excite Rossby waves that can export water to the extratropics. Thus, incorporating SSS, a sensitive indicator of regional oceanic rainfall, can enhance the accuracy of existing precipitation prediction frameworks that rely on sea surface temperature-based climate indices and, by extension, improve watershed management.