A
gyre in
oceanography is any large system of rotating
ocean currents, particularly those involved with large
wind movements. Gyres are caused by the
Coriolis effect; planetary
vorticity along with horizontal and vertical friction, determine the circulation patterns from the wind curl (
torque). The term
gyre can be used to refer to any type of
vortex in the
air or the sea, even one that is man-made, but it is most commonly used in
oceanography to refer to the major
ocean systems.