The Physics Factbook™
Edited by Glenn Elert -- Written by his students
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|Coble, Charles R., Elaine G. Murray, and Dale R. Rice. Earth Science. 3rd ed. Englewood Cliffs, NJ: Prentice Hall, 1987: 256-257.||"The Gulf Stream moves at speeds greater than 1.5 meters per second."||1.5 m/s|
|Adams, John, et al. "Ocean Currents." Microsoft Encarta. 2 vols. CD-ROM. Redmond: Microsoft, 1999. 191.||"Whereas speeds of surface currents can reach as high as 250 cm/sec (98 in/sec, or 5.6 mph) a maximum for the Gulf Stream, speeds of deep currents vary from 2 to 10 cm/sec (0.8 to 4 in/sec) or less."||2.5 m/s
|Gaskell, T F. The Gulf Stream. New York: John Day Company, 1973. 95.||"At the narrowest point of the Florida Straits, the water masses in a cross section approximately 70 km wide and 200 m deep are moved forward at a speed of more than 1m/sec are moved forward at a speed of more than 1 m/s."||1 m/s|
|Gross, M.G. Oceanography: A View of the Earth. 3rd ed. New York: Prentice Hall, 1982: 173, 177.||"Meanders move slowly northeastward with the Gulf Stream at speeds of 8 to 25 centimeters per second (7 to 22 kilometers per day)."||0.08–0.25 m/s|
|Gross, M G. Oceanography. 6th ed. Columbus: Merrill, 1990: 74-75.||"The relatively narrow, jet-like currents of the Gulf Stream system and the Kuroshio off Japan are the largest currents in the ocean. They have speeds between 40 and 120 km/day (25 to 75 mi/day)."||0.4–1.3 m/s|
Ocean waters move continuously. Anyone who sails or swims in the ocean knows the horizontal water movements called currents. Some currents are transient features and affect only a small area, such as a beach; these are the ocean's response to local-often seasonal-conditions. Other currents extend over large parts of the world ocean; these are the response of the ocean and atmosphere to the energy flow from the tropics and subtropics to sub-polar and polar regions.
The speed of these current varies based on the gyres, or currents that are kept in motion by prevailing winds. Each gyre consists of four currents. Open-ocean, east-west currents form the gyre's northern and southern limbs and boundary currents sitting nearly parallel to the continental margins, generally oriented north south, join these gyres. The North Pacific Current or the North and South Equatorial currents travel at speed of 0.03 to 0.06 m/s. The Gulf Stream, and the Kuroshio Currents flow with speed up to 0.4 to 1.2 m/s. California Currents and the Canary Current travel at 0.03 to 0.07 m/s.
These speed measurements come mainly from observations of surface currents that begun early in the 19th century. These observations were important especially for merchant ships, which traveled the oceans back and forth. These ships took courses that often had discrepancies between their intended position and their actual position after they had traveled for a period. The discrepancies were caused by the deflection of the ships by surface currents (which could reach speeds as high as 2.5 m/s). Thus the knowledge of the direction and speed of the local current became important, as it could be deduced from a ship's actual position after it has been steered on a given course, to obtain the desired course.
Eugene Statnikov -- 2002
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