Why do two oceans never mix

Science in dialogue

Do the different oceans mix with one another?

The Arctic Ocean, Pacific and Atlantic are separated by continents, but by no means isolated from each other. Pacific and Atlantic seawater flow into the Arctic basin through the Bering Strait and Fram Strait.

In general, people like to fall back on the model of the so-called conveyor belt of a global flow system. Then warm water masses on the surface and cold, salty water masses in deeper ocean layers are transported like on a conveyor belt.

The water transported by the Gulf Stream into the North Atlantic gives off its heat to the atmosphere, becomes cooler and heavier and consequently sinks into deeper ocean layers.

In the depths, the water flows south to the Antarctic Circumpolar Current. This distributes the Atlantic water masses in the Indian and Pacific Ocean. Here they come to the surface again on their way north, turn around and flow around the southern tip of Africa back into the Atlantic.

In reality, however, the flow conditions are far more complex than in the conveyor belt model, which, for example, does not take into account the strong influence of the wind systems or the eddies on the water surface.

This question was answered by Jana Stone and Albert Gerdes from MARUM - Center for Marine Environmental Sciences at the University of Bremen.