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Discovery and quantification of the Atlantic Meridional Overturning Circulation: the importance of 25N

By H.R. Longworth and H.L. Bryden


Here we present a review of the history of modern understanding of the strength of the Atlantic Meridional Overturning Circulation (MOC), which arguably originates in 1957. This was the year that the Discovery cruises not only observed the Atlantic deep western boundary current for the first time, but also completed a transatlantic section along 24ºN, from which reliable estimates of the size and structure of the MOC were later obtained. It was also the <br/>year Stommel began to publish his estimates of the size of the Atlantic overturning. These key developments are put into the context of early qualitative pictures of the Atlantic MOC which can be traced back to 1798. The early proposals differed significantly from Wüst’s qualitative<br/>picture of layered interhemispheric exchange, published in 1935 but still broadly accepted today, and on which subsequent quantification relied. Early estimates of the Atlantic MOC strength, as by-products of regional circulation schemes, were by today’s standard weak at 6-8 Sv. Stommel’s work from 1957 and later developments in the 1980’s produced much stronger overturning. Recognition of the importance of the MOC’s role in meridional heat transport, necessitating studies dedicated to its quantification, led to a consensus regarding its strength in the early 1980’s. The accepted 16-18 Sv MOC resulting from the 1957 Discovery section analysis supported Stommel’s 1957 work and has since been verified by independent observations. We examine only the steady state MOC here, understanding and quantification of its variability are still very much evolving

Topics: GC
Publisher: American Geophysical Union
Year: 2007
OAI identifier:
Provided by: e-Prints Soton

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  3. (1957). A survey of ocean current theory. doi
  4. (1985). An early theory of ocean circulation: doi
  5. (1996). An estimate of global ocean circulation and heat fluxes. doi
  6. (1961). An observation of a deep countercurrent in the western North Atlantic. doi
  7. (1999). Atlantic Ocean baroclinic heat flux at 24 to 26ºN. doi
  8. (2001). Decreasing overflow from the Nordic seas into the Atlantic Ocean through the Faroe Bank channel since doi
  9. (1981). Deep circulation of the World Ocean. Evolution of Physical Oceanography,
  10. (1977). Determining the general circulation of the oceans: A preliminary discussion. doi
  11. (1982). Direct estimates and mechanisms of ocean heat transport, doi
  12. (2003). Error budget of inverse box models: The North Atlantic. doi
  13. (1980). Estimation of meridional heat flux in the North Atlantic by inverse methods, doi
  14. (2005). From Discovery to discovery: the hydrology of the Southern Ocean, doi
  15. (1980). Heat transport by currents across 25ºN latitude in the Atlantic Ocean. doi
  16. (1955). Heat Transport in the North Atlantic Ocean. Ref 53-54T, Department of Oceanography, A and M College of Texas,
  17. (1999). Impact of Interbasin Exchange on the Atlantic Overturning Circulation. doi
  18. (2000). Improved estimates of global ocean circulation, heat transport and mixing from hydrographic data. doi
  19. (1957). Measurements of deep currents in the western North Atlantic, doi
  20. (1962). Measurements of meridional heat transport by ocean currents. doi
  21. (2003). Mechanisms of heat, freshwater, oxygen and nutrient transports and budgets at 24.5ºN in the subtropical North Atlantic. doi
  22. (1980). Meridional heat flux of the North Atlantic Ocean, doi
  23. (1998). Meridional transport and heat flux variations in the subtopical North Atlantic. The Global Atmosphere and Ocean System,
  24. (1996). Moored observations of Western Boundary Current variability and Thermohaline Circulation at 26.5ºN in the Subtropical North Atlantic. doi
  25. (1952). Note on the meridional transport of energy by the oceans.
  26. (2001). Ocean gyre circulation changes associated with the North Atlantic Oscillation. doi
  27. (1993). Ocean heat transport across 24ºN latitude. Interactions Between Global Climate Subsystems: The Legacy of doi
  28. (1958). Oceanographic Data from the RRS Discovery II during the International Geophysical Year, Woods Hole Oceanographic Institution doi
  29. (1977). On the crossover between the Gulf Stream and the Western Boundary Undercurrent. doi
  30. (1995). On the interbasin-scale thermohaline circulation. doi
  31. (1981). On the mid-depth circulation of the World Ocean. Evolution of Physical Oceanography,
  32. (1976). On the North Atlantic circulation. doi
  33. (1991). On the sources of the Florida Current. doi
  34. (1951). Oxygen, phosphate and nitrate in the Atlantic Ocean.
  35. (1941). Quantitative Untersuchungen zur Statik und Dynamik des Atlantischen Ozeans. Die relative Topographie Einzelner Druckflachen im Atlantischen Ozean (The Relative Topography of individual pressure surfaces of the Atlantic Ocean).
  36. (2002). Rapid freshening of the deep North Atlantic Ocean over the past four decades. doi
  37. (1994). Rising temperatures in the subtropical North Atlantic Ocean over the past 35 years. doi
  38. (1971). Scientists and the Sea 1650-1990. A study of marine science. doi
  39. (1973). Seasonal variability of the Florida Current,
  40. (2001). Sixteen years of Florida Current transport at 27ºN. doi
  41. (2005). Slowing of the Atlantic meridional overturning circulation at 25ºN. doi
  42. (1958). Some examples of stationary planetary flow patterns in bounded basins. doi
  43. (1991). South Atlantic interbasin exchange. doi
  44. (1955). Stromgeschwindigkeiten im Tiefen-
  45. (1991). The Great Ocean Conveyor. doi
  46. (1958). The Gulf Stream. doi
  47. (1978). The North Atlantic General Circulation West of 50ºW Determined by Inverse Methods. doi
  48. (2001). The North Atlantic Oscillation. doi
  49. (1942). The Oceans: their Physics, doi
  50. (1992). Thermocline and intermediate water communication between the South Atlantic and Indian Oceans. doi
  51. (1992). Transport and heat flux of the Florida Current at 27ºN derived from crossstream voltages and profiling data: theory and observations. doi
  52. (1985). Two transatlantic sections: meridional circulation and heat flux in the subtropical North Atlantic Ocean. doi
  53. (1984). Warm-to-cold water conversion in the northern North Atlantic ocean. doi
  54. (1971). Water masses and circulation patterns in the region of the Blake-Bahama Outer Ridge. doi
  55. Wissenschaftliche Ergebnisse der Deutschen Atlantischen Expedition auf dem Forschungs und Vermessungsschiff “Meteor” 1925-1927. 6: 2nd Part. doi
  56. (1978). Wissenschaftliche Ergebnisse der Deutschen Atlantischen Expedition auf dem forschuungs und Vermessungsschiff “Meteor” 1925-1927. 6: 1st Part. doi

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