What is the gyre effect?
In oceanography, a gyre (/ˈdʒaɪər/) is any large system of circulating ocean currents, particularly those involved with large wind movements. Gyres are caused by the Coriolis effect; planetary vorticity, horizontal friction and vertical friction determine the circulatory patterns from the wind stress curl (torque).
What affects ocean currents most?
Winds, water density, and tides all drive ocean currents. Coastal and sea floor features influence their location, direction, and speed. Earth's rotation results in the Coriolis effect which also influences ocean currents.