Ocean water circulates in currents. Surface currents are caused mainly by wind and affect the uppermost 10% of the ocean. Circulation of the other 90% of the ocean is driven by gravity, as dense water sinks and less dense water rises. Upwelling and downwelling describe the vertical movement of water masses. An ocean gyre is a large system of circular ocean currents formed by global wind patterns and forces created by Earth’s rotation. The movement of the world’s major ocean gyres helps drive the “ocean conveyor belt.”

what causes ocean currents to form. heat from the sun (temperatures), wind, sanity (saltiness), land masses acting as barriers, & the rotation of earth. deep ocean currents. currents that flow far beneath the surface of the ocean resulting in a convection current that takes many years to circulate. When wind blows over the ocean around these pressure centers, surface waves are generated by transferring some of the wind's energy, in the form of momentum, from the air to the water. This constant push on the surface of the ocean is the force that forms the surface currents.