The high salinity water coming from the south cools and becomes denser.
Explanation:
In North Atlantic Ocean north, Atlantic deep water is formed. Flow of warm water surface from southern water surface into the Atlantic Ocean Thermohaline circulation is involved. Regulation of global system of current is called global conveyor belt.
In north Atlantic nearest pole conveyor belt begins which is in the surface part of the ocean. Due to temperature of Arctic water become chilled. When ice become freeze and salt can’t be freeze then it left in ocean than the water become salt.