365 Days of Climate Awareness 44: Ocean Currents 2 — Thermohaline Circulation
Temperature and salinity are the main factors which determine the density of seawater, and they drive the bulk of vertical water motion in the ocean worldwide.
The second major driver of ocean currents is density, dubbed the “thermohaline circulation”, from the Greek “thermos”, or heat, and “hals”, or salt. Temperature and salinity are the main factors which determine the density of seawater, and they drive the bulk of vertical water motion in the ocean worldwide. When combined with the wind-driven surface currents, these density currents help form a rough, slow, conveyor belt of circulation around the world.
One of the main thermohaline processes is evaporation. When a large amount of ocean water in a given location evaporates, it leaves a much cooler body of water behind, denser than the surrounding water. The colder, denser water sinks either to the bottom, or to a depth where the surrounding water is equally dense. In the Weddell Sea off Antarctica, these convective events produce Antarctic Bottom Water, which spreads northward through the Atlantic. In the North Atlantic, east of Greenland, the last of the North Atlantic Current…
