The field of oceanography encompasses both surface currents and deep water circulation. Surface currents and the overturning water that forms deep water currents, distribute heat and salt between different regions of the Earth as well as with depth in the oceans.
In oceanography, the mechanisms of the ocean circulation is studied. Scientists use observations from satellites and expeditions together with theoretical and numerical models. By studying the oceanic and atmospheric overturning circulation it is possible to track e.g. heat, salt and moisture exchanges between low and high latitudes.
Oceanic circulation has changed through the course of time and some scientist study short term to long term marine climate change as well as processes at the sea-air interface.
