• The oceans are mostly composed of warm salty water near the surface over cold, less salty water in the ocean depths. These two regions don't mix except in certain special areas.
  • The ocean currents, the movement of the ocean in the surface layer, are driven mostly by the wind.
  • In certain areas near the polar oceans, the colder surface water also gets saltier due to evaporation or sea ice formation. This is a very large, slow current called the thermohaline circulation because it is caused by temperature and salinity (haline) variations.
  • Ocean currents circulate all over the globeworld_ocean_map_2.jpg

The main current in the Southern Ocean is the Antarctic Circumpolar Current - The big ACC!

(Circumpolar means it is located around a polar region) It flows from west to east, all the way around Antarctica. The ACC is huge! It is the biggest current in the world and can move up to 150 billion litres per second of water. It can reach speeds in narrow channels of up to 1 metre per second.
This is the same as 150 times the water contained in all the rivers in the world, or the water contained in 75,000 Olympic swimming pools going past every second!
The volume of water that is transported by the ACC is so large, not because it flows fast, but because of the depth. It has a depth of up to 4000m and is from just south of New Zealand to most of the way to Antarctica.
The Southern Ocean is one of the top places for wind on Earth, and these winds move the currents. Friction between the sea water and the bottom of the ocean cause the movement of the water or current to slow down. It is the balance between these two forces that stop the currents from getting faster and faster.

The major currents are
  • the North and South Equatorial Currents,
  • the Gulf Stream ,
  • the Kuroshio Current,
  • the Antarctic Circumpolar Current, the East Australian Current.

The two largest currents on earth are the Kuroshio Current which circulates near Japan, and the Antarctic Circumpolar Current, which circulates around Antarctica .
In the Movie Finding Nemo, the father fish Marlin meets a group of gnarly turtles who travel on the East Australian Current.

joruler.gifMeasuring Ocean Currents.
There are a number of ways to do this. Click on this link to a webpage that shows you various instruments and what they do