Sverdrup

Sverdrup is the standard unit of volumetric transport used in oceanography. One Sverdrup (Sv) equals 1,000,000 cubic meters per second (10^6 m^3/s). It is commonly used to express the meridional (north–south) transport of water in ocean basins.

The unit is named after Harald Ulrik Sverdrup, a Norwegian oceanographer (1888–1957). Sverdrup is best known for developing a theoretical framework that relates the curl of surface wind stress to the depth-integrated northward or southward transport in the ocean, a concept often referred to as the Sverdrup transport or Sverdrup balance. This theory helped explain how wind forcing could generate large-scale, basin-wide circulation patterns.

In practice, Sverdrup transport describes the wind-driven, depth-integrated meridional flow in the interior ocean under idealized conditions (such as a beta-plane and simplified boundary effects). It provides a first-order explanation for the formation of subtropical gyres and other large-scale circulation features, although real oceans exhibit deviations caused by bottom topography, friction, and mesoscale eddies.

Examples of transports described in Sverdrup terms include the Antarctic Circumpolar Current, which is among the largest individual transports, on the order of tens to over a hundred Sv. The Gulf Stream and the North Atlantic subtropical gyre contribute significant but smaller amounts, while many basins exhibit more modest Sverdrup-scale transports. The Sverdrup unit remains widely used in oceanographic literature and data analyses for expressing large-scale, wind-driven meridional transports.