On the role of the freshwater budget at the origin of the salinity minimum at intermediate depths in the northern Pacific

Seasonal variability of the salinity field shows that the salinity minimum at subsurface (intermediate) depths is a temporal phenomenon and not a water mass in the common interpretation of the term. This extremum in the vertical salinity distribution appears and disappears as the freshwater budget changes sign on different timescales. Its characteristics are a function of the freshwater budget; they change in time. The salinity minimum appears and disappears seasonally in the transition zone associated with an ocean basin where the freshwater budget changes sign on the seasonal timescale. The long-lasting salinity minimum at intermediate depths in the arid ocean zone is attributed to air-sea interaction on long-term (climate) timescales. Its existence is due to one of the phases of this interaction, the continuous salt flux from the ocean surface.