Gyre
Also called: Ocean gyre · Topic: Movements of Ocean Water: Waves, Tides and Currents · NCERT: Class 11, Ch 13 "Movements of Ocean Water"
Meaning
A gyre is a large circular system of ocean currents that loops around a pile of water in an ocean basin. Planetary winds push the water, and the Coriolis force (the turning effect of Earth's rotation) bends it into a loop. Gyres turn clockwise in the Northern Hemisphere and anticlockwise in the Southern Hemisphere. There are five main subtropical gyres: North Pacific, South Pacific, North Atlantic, South Atlantic and Indian Ocean. Their calm centres trap floating plastic.
Example
The southern Indian Ocean gyre turns anticlockwise. The South Equatorial Current flows west, the warm Agulhas Current flows south along South Africa, the West Wind Drift carries water east, and the cold West Australian Current flows north to close the loop.
Don't confuse with
- North Indian Ocean circulation: this does not keep a fixed direction. It turns clockwise in summer and anticlockwise in winter because the monsoon winds reverse.
Related concepts
- Ocean current
- Forces driving ocean currents
- Ekman transport
- Surface currents
- Deep water currents
- Warm current
- Cold current