oceanography Oceanography (), also known as oceanology and ocean science, is the scientific study of the oceans. It is an Earth science, which covers a wide range of topics, including ecosystem dynamics; ocean currents, waves, and geophysical fluid dynamic ...

, the sverdrup (symbol: Sv) is a non- SI

metric unit The metric system is a system of measurement that succeeded the decimalised system based on the metre that had been introduced in France in the 1790s. The historical development of these systems culminated in the definition of the Internati ...

volumetric flow rate In physics and engineering, in particular fluid dynamics, the volumetric flow rate (also known as volume flow rate, or volume velocity) is the volume of fluid which passes per unit time; usually it is represented by the symbol (sometimes ). I ...

, with equal to . It is equivalent to the SI derived unit cubic

hectometer The hectometre ( International spelling as used by the International Bureau of Weights and Measures; SI symbol: hm) or hectometer (American spelling) is a unit of length in the International System of Units (SI), equal to one hundred metres and ...

per second (symbol: hm³/s or hm³⋅s⁻¹): 1 Sv is equal to 1 hm³/s. It is used almost exclusively in

to measure the volumetric rate of transport of

ocean current An ocean current is a continuous, directed movement of sea water generated by a number of forces acting upon the water, including wind, the Coriolis effect, breaking waves, cabbeling, and temperature and salinity differences. Depth contours, s ...

s. It is named after Harald Sverdrup. One sverdrup is about five times what is carried by the world’s largest river, the Amazon. In the context of

s, a volume of one million cubic meters may be imagined as a "slice" of ocean with dimensions × × (width × length × thickness). At this scale, these units can be more easily compared in terms of width of the current (several km), depth (hundreds of meters), and current speed (as

meters per second The metre (British spelling) or meter (American spelling; see spelling differences) (from the French unit , from the Greek noun , "measure"), symbol m, is the primary unit of length in the International System of Units (SI), though its prefi ...

). Thus, a hypothetical current wide, 500 m (0.5 km) deep, and moving at 2 m/s would be transporting of water. The sverdrup is distinct from the SI

sievert The sievert (symbol: SvNot be confused with the sverdrup or the svedberg, two non-SI units that sometimes use the same symbol.) is a unit in the International System of Units (SI) intended to represent the stochastic health risk of ionizing radi ...

unit or the non-SI

svedberg A Svedberg unit or svedberg (symbol S, sometimes Sv) is a non- SI metric unit for sedimentation coefficients. The Svedberg unit offers a measure of a particle's size indirectly based on its sedimentation rate under acceleration (i.e. how fast a p ...

unit. All three use the same symbol. They are not related.

History

The sverdrup is named in honor of the Norwegian oceanographer, meteorologist and polar explorer Harald Ulrik Sverdrup (1888–1957), who wrote the 1942 volume ''The Oceans, Their Physics, Chemistry, and General Biology'' together with Martin W. Johnson and Richard H. Fleming. In the 1950s and early 1960s both Soviet and North American scientists contemplated the damming of the Bering Strait, thus enabling temperate Atlantic water to heat up the cold Arctic Sea and, the theory went, making Siberia and northern Canada more habitable. As part of the North American team, Canadian oceanographer Maxwell Dunbar found it "very cumbersome" to repeatedly reference millions of cubic meters per second. He casually suggested that as a new unit of water flow, "the inflow through Bering Strait is one sverdrup". At the Arctic Basin Symposium in October 1962, the unit came into general usage.

Examples

The water transport in the

Gulf Stream The Gulf Stream, together with its northern extension the North Atlantic Current, North Atlantic Drift, is a warm and swift Atlantic Ocean, Atlantic ocean current that originates in the Gulf of Mexico and flows through the Straits of Florida a ...

gradually increases from in the

Florida Current The Florida Current is a thermal ocean current that flows from the Straits of Florida around the Florida Peninsula and along the southeastern coast of the United States before joining the Gulf Stream Current near Cape Hatteras. Its contributing ...

to a maximum of south of Newfoundland at 55° W

longitude Longitude (, ) is a geographic coordinate that specifies the east–west position of a point on the surface of the Earth, or another celestial body. It is an angular measurement, usually expressed in degrees and denoted by the Greek letter l ...

. The

Antarctic Circumpolar Current The Antarctic Circumpolar Current (ACC) is an ocean current that flows clockwise (as seen from the South Pole) from west to east around Antarctica. An alternative name for the ACC is the West Wind Drift. The ACC is the dominant circulation feat ...

, at approximately , is the largest ocean current. The entire global input of

fresh water Fresh water or freshwater is any naturally occurring liquid or frozen water containing low concentrations of dissolved salts and other total dissolved solids. Although the term specifically excludes seawater and brackish water, it does include ...

from rivers to the ocean is approximately .

References

{{Reflist Oceanography Units of flow Non-SI metric units