Oceancirkulation

Oceancirkulation refers to the large-scale movement of seawater within the world’s oceans, including surface currents, subsurface flows, and deep-water movements. Surface currents are primarily wind-driven, arising from prevailing wind patterns and the Coriolis effect, and they organize into wide gyres in each ocean basin. Prominent examples include the Gulf Stream and its North Atlantic drift, the Kuroshio in the western North Pacific, and the eastern boundary currents in various basins.

Deep and thermohaline circulation arises from density differences caused by variations in temperature and salinity. The global circulation, often described as an ocean conveyor belt, links basins through vertical and horizontal exchanges, moving water masses such as North Atlantic Deep Water and Antarctic Bottom Water. These deep flows regulate climate, redistribute heat and nutrients, and influence regional sea levels.

Oceancirkulation is a central component of the Earth’s climate system because it transports heat from equatorial to higher latitudes, moderates regional climates, and sustains marine ecosystems. It exhibits natural variability on multiple timescales, including phenomena such as El Niño–Southern Oscillation and the Pacific Decadal Oscillation, and may undergo long-term changes under climate forcing, including potential alterations to major currents like the Atlantic Meridional Overturning Circulation.

Measurement and modelling rely on satellite altimetry for sea-surface height, ARGO profiling floats for temperature and salinity, and in-situ observations from ships and moorings, complemented by ocean–atmosphere models to simulate circulation patterns and project future responses to climate change.