Sea surface salinity response to variations in the Aleutian Low

The strength of the atmospheric Aleutian Low pressure system varies interannually and has a distinct impact on sea surface temperature (SST), sea level, and other oceanic parameters along the North Pacific subarctic front. These impacts are caused by variable zonal winds through their effects on meridional Ekman transport and air-sea fluxes. While the SST response is well known on an interannual (ENSO) to decadal (PDO) scale, the response of sea surface salinity (SSS) is less known due to relatively sparse observations. The SSS response originates in the western Pacific and is concentrated along the North Pacific subarctic front, reaching a few tenths of psu in the upper 100 m, as demonstrated by satellite SSS, Argo salinity data, and model simulations. SSS anomalies, in contrast to SST anomalies, behave like passive tracers that are advected eastward in the North Pacific Current across the whole basin and, unexpectedly, sometimes intensify to the east. After reaching the eastern boundary, they continue predominantly southward along the California coast, remaining detectable by satellite SSS all the way to the southern tip of the California peninsula.

Automated summary

The strength of the atmospheric Aleutian Low pressure system has a significant impact on the sea surface temperature, sea level, and other oceanic parameters along the North Pacific subarctic front, primarily through variable zonal winds and their effects on meridional Ekman transport and air-sea fluxes. While the response of sea surface temperature is well understood, the response of sea surface salinity is less known due to limited observations. However, recent studies using satellite data, Argo salinity data, and model simulations have revealed that sea surface salinity anomalies behave like passive tracers, being advected eastward by the North Pacific Current and intensifying at times before they continue southward along the California coast.