The North Atlantic nutrient stream

Abstract

Western boundary currents are the locus of intense nutrient transport, or nutrient streams. The largest fraction of this transport takes place in the upper-thermocline layers, between the surface layers (where speed reaches a maximum) and the nutrient bearing strata of the subtropical gyres (where nutrient concentration is maximum). The core of the nutrient stream of the North Atlantic subtropical gyre is located slightly offshore the Gulf Stream, its density coordinate centered on the 26.5−27.3σθ−band, approximately constant along the axis of the stream. During late spring and summer the nutrient stream reaches the surface seasonal mixed layer at the outcropping of this isopycnal band. We argue that this must be a principal factor sustaining the seasonal high productivity of the subpolar North Atlantic Ocean. Additionally, we investigate the possibility of intermittent shear-induced diapycnal mixing in the upper-thermocline layers of the Gulf Stream, induced by frontogenesis taking place during some phase of the meanders. Here we illustrate that diapycnal mixing has a maximum at the location of the nutrient stream, being associated to observed nutrient anomalies. We suggest that diapycnal mixing associated to the passage of steep meanders brings nutrients from the nutrient stream to the shallow photic layers, and sustains intermittent (day-to-week) patchy (10–100 km) productivity over the stream itself.

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References

  1. Arnone, R. A., R. W. Nero, J. M. Jech and I. de Palma (1990): Acoustic imaging of biological and physical processes within Gulf Stream meanders.Eos Trans. Am. Geophys. Union,71, 982.

    Google Scholar 

  2. Ashjian, C. J. (1993): Trends in copepod species abundances across and along a Gulf Stream meander: evidence for entrainment and detrainment of fluid parcels from the Gulf Stream.Deep-Sea Res.,40, 461–482.

    Google Scholar 

  3. Ashjian, C. J., S. L. Smith, C. N. Flagg, A. J. Mariano, W. J. Behrens and P. V. Z. Lane (1994): The influence of a Gulf Stream meander on the distribution of zooplankton biomass in the Slope Water, the Gulf Stream and the Sargasso Sea, described using a shipboard acoustic Doppler current profiler.Deep-Sea Res.,41, 23–50.

    Google Scholar 

  4. Atkinson, L. P., T. N. Lee, J. O. Blanton and G. Paffenhöfer (1987): Summer upwelling on the southeastern continental shelf of the U.S.A. during 1981. Hydrographic observations.Prog. Oceanogr.,19, 231–266.

    Google Scholar 

  5. Bolin, B., A. Bjorkstrom, K. Holmén and B. Moore (1983): The simultaneous use of tracers for ocean circulation studies.Tellus,35, 206–236.

    Google Scholar 

  6. Bower, A. S. (1989): Potential vorticity balances and horizontal divergence along particle trajectories in Gulf Stream meanders east of Cape Hatteras.J. Phys. Oceanogr.,19, 1669–1681.

    Google Scholar 

  7. Bower, A. S. and T. Rossby (1989): Evidence of cross-frontal exchange processes in the Gulf Stream based on isopycnal RAFOS float data.J. Phys. Oceanogr.,19, 1177–1190.

    Google Scholar 

  8. Brewer, P. G. and D. Dyrssen (1987): Ocean chemical fluxes across 25°N in the Atlantic Ocean. Discussion paper at International GOFS Meeting, Paris, February 17–20, 25 pp.

  9. Brown, O. B., R. H. Evans, J. W. Brown, R. H. Gordon, R. C. Smith and K. S. Baker (1984): Blooming off the U.S. East Coast: A satellite description. p. 67–84. InGlobal Ocean Flux Study, National Academy Press, Washington.

    Google Scholar 

  10. Brown, O., R. Evans, R. Watts, C. Casagrande, P. Hamilton, W. Boicourt and G. Csanady (1987):Study of Physical Processes on the U.S. Mid-Atlantic Continental Slope and Rise. Minerals Management Service Report No. 87-0024, 506 pp.

  11. Csanady, G. T. (1989): Energy dissipation and upwelling in a western boundary current.J. Phys. Oceanogr.,19, 462–473.

    Google Scholar 

  12. Csanady, G. T. (1990): Physical basis of coastal productivity. The SEEP and MASAR experiments.Eos Trans. Am. Geophys. Union,71, 1060–1065.

    Google Scholar 

  13. Csanady, G. T. and P. Hamilton (1988): Circulation of slopewater.Cont. Shelf Res.,8, 565–624.

    Google Scholar 

  14. Darzi, M., J. Chen, J. K. Firestone and C. R. McClain (1989): SEAPAK: A satellite image analysis system for oceanographic research. Preprint Volume, 5th International Conference on Interactive and Information Processing Systems for Meteorology, Oceanography and Hydrology, American Meteorological Society, Boston, Massachusetts, pp. 26–32.

  15. Esaias, W. E., G. C. Feldman, C. R. McClain and J. A. Elrod (1986): Monthly satellite-derived phytoplankton pigment distribution for the North Atlantic basin.Eos Trans. Am. Geophys. Union,67, 835–837.

    Google Scholar 

  16. Firestone, J. K., G. Fu, J. Chen, M. Darzi and C. R. McClain (1989): PC-SEAPAK: A state-of-the-art image display and analysis system for NASA's oceanographic research program. Preprint Volume, 5th International Conference on Interactive and Information Processing Systems for Meteorology, Oceanography and Hydrology, American Meteorological Society, Boston, Massachusetts, pp. 33–40.

  17. Flierl, G. R. and C. S. Davis (1993): Biological effects of Gulf Stream meandering.J. Mar. Res.,51, 529–560.

    Google Scholar 

  18. Gargett, A. E. (1991): Physical processes and the maintenance of nutrient-rich euphotic zones.Limnol. Oceanogr.,36, 1527–1545.

    Google Scholar 

  19. Garside, C. and J. C. Garside (1993): The “f-ratio” on 20°W during the North Atlantic Bloom Experiment.Deep-Sea Res.,40, 75–90.

    Google Scholar 

  20. Hitchcock, G. L., A. J. Mariano and T. Rossby (1993): Mesoscale pigment fields in the Gulf Stream: Observations in a meander crest and trough.J. Geophys. Res.,98, 8425–8445.

    Google Scholar 

  21. Ishizaka, J., H. Fukushima, M. Kishino, T. Kishino, T. Saino and M. Takahashi (1992): Phytoplankton pigment distributions in regional upwelling around the Izu Peninsula detected by Coastal Zone Color Scanner on May 1982.J. Oceanogr.,48, 305–327.

    Google Scholar 

  22. Jenkins, W. J. (1980): Tritium and3He in the Sargasso Sea.J. Mar. Res.,38, 533–569.

    Google Scholar 

  23. Jenkins, W. J. (1987):3H and3He in the Beta Triangle: observations of gyre ventilation and oxygen utilization rates.J. Phys. Oceanogr.,17, 763–783.

    Google Scholar 

  24. Kawase, M. and J. L. Sarmiento (1985): Nutrients in the Atlantic thermocline.J. Geophys. Res.,90, 8961–8979.

    Google Scholar 

  25. Kirwan, A. D. (1963):Circulation of Antarctic Intermediate Water Deduced through Isentropic Analysis. Reference 63-34F, Texas A & M University, College Station, Texas, 34 pp.

    Google Scholar 

  26. Leetma, A. and A. F. Bunker (1978): Updated charts of the mean annual wind stress, convergences in the Ekman layers, and Sverdrup transports in the North Atlantic.J. Mar. Res.,36, 311–322.

    Google Scholar 

  27. Levitus, S. (1982):Climatological Atlas of the World Ocean. NOAA Professional Paper 13, U.S. Government Printing Office, Washington, D.C.

    Google Scholar 

  28. Lohrenz, S. E., J. J. Cullen, D. A. Phinney, D. B. Olson and C. S. Yentsch (1993): Distributions of pigments and primary production in a Gulf Stream meander.J. Geophys. Res.,98, 14545–14560.

    Google Scholar 

  29. Luyten, J. and H. Stommel (1986): Gyres driven by combined wind and buoyancy flux.J. Phys. Oceanogr.,16, 1551–1560.

    Google Scholar 

  30. Luyten, J., J. Pedlosky and H. Stommel (1983): The ventilated thermocline.J. Phys. Oceanogr.,13, 292–309.

    Google Scholar 

  31. Marra, J. and C. Ho (1993): Initiation of the spring bloom in the northeast Atlantic (47°N, 20°W): a numerical simulation.Deep-Sea Res.,40, 55–73.

    Google Scholar 

  32. Martin, J. H., G. A. Knauser, D. M. Karl and W. W. Broenkow (1987): VERTEX: carbon cycling in the northwest Pacific.Deep-Sea Res.,34, 267–285.

    Google Scholar 

  33. Martins, A. M., E. E. Hofmann and C. R. McClain (1995): CZCS-derived pigment data for the southeastern U.S. continental shelf from 1978 to 1986 (October to May). Part III: Atmospheric correction, pigment time series, and comparison with in situ data. Old Dominion University Research Foundation Report No. 95-06, 299 pp.

  34. Montgomery, R. B. (1937): A suggested method for representing gradient flow in isentropic surfaces.Bull. Am. Meteorol. Soc.,18, 210–212.

    Google Scholar 

  35. Montgomery, R. B. (1938): Circulation in upper layers of Southern North Atlantic deduced with use of isentropic analysis.Papers Phys. Oceanogr. Meteorol.,6, 1–55.

    Google Scholar 

  36. Munk, W. H. (1950): On the wind-driven ocean circulation.J. Meteorol.,7, 79–93.

    Google Scholar 

  37. Newton, C. W. (1978): Fronts and wave disturbances in Gulf Stream and atmospheric jet stream.J. Geophys. Res.,83, 4697–4706.

    Google Scholar 

  38. Nurser, A. J. G. and J. C. Marshall (1991): On the relationship between subduction rates and diabatic forcing of the mixed layer.J. Phys. Oceanogr.,21, 1793–1802.

    Google Scholar 

  39. Pelegrí, J. L. and G. T. Csanady (1991): Nutrient transport and mixing in the Gulf Stream.J. Geophys. Res.,96, 2577–2583.

    Google Scholar 

  40. Pelegrí, J. L. and G. T. Csanady (1994): Diapycnal mixing in western boundary currents.J. Geophys. Res.,99, 18275–18304.

    Google Scholar 

  41. Redfield, A. C. (1936): An ecological aspect of the Gulf Stream.Nature,138, 1013.

    Google Scholar 

  42. Reid, J. L. (1965):Intermediate Waters of the Pacific Ocean, Vol. 2. The Johns Hopkins Oceanographic Studies, John Hopkins University Press, Baltimore, 85 pp.

    Google Scholar 

  43. Reid, J. L. (1981) On the mid-depth circulation of the world ocean. p. 70–111. InEvolution of Physical Oceanography, ed. by B. A. Warren, MIT Press, Cambridge.

    Google Scholar 

  44. Reid, J. L. (1994): On the total geostrophic circulation of the North Atlantic Ocean: Flow patterns, tracers, and transports.Prog. Oceanogr.,33, 1–92.

    Google Scholar 

  45. Rhines, P. B. and W. Y. Young (1982): A theory of wind-driven circulation. I. Mid-ocean gyres.J. Mar. Res.,40, 559–596.

    Google Scholar 

  46. Richards, A. F. and A. C. Redfield (1955): Oxygen-density relationships in the western North Atlantic.Deep-Sea Res.,2, 182–199.

    Google Scholar 

  47. Richardson, P. L. (1983): Eddy kinetic energy in the North Atlantic from surface drifters.J. Geophys. Res.,88, 4355–4367.

    Google Scholar 

  48. Riley, G. A. (1951): Oxygen, phosphate and nitrate in the Atlantic Ocean.Bull. Bingham Oceanogr. Collection,13, 1–125.

    Google Scholar 

  49. Rintoul, S. R. and C. Wunsch (1991): Mass, heat, oxygen and nutrient fluxes and budgets in the North Atlantic Ocean.Deep-Sea Res.,38, Suppl. 1, S619-S644.

    Google Scholar 

  50. Roemmich, D. and C. Wunsch (1985): Two transatlantic sections: meridional circulation and heat flux in the subtropical North Atlantic Ocean.Deep-Sea Res.,32, 619–644.

    Google Scholar 

  51. Rossby, C. G. (1936): Dynamics of steady ocean currents in the light of experimental fluid mechanics.Papers Phys. Oceanogr. Meteorol.,5, 1–43.

    Google Scholar 

  52. Sarmiento, J. L. (1983): A tritium box model of the North Atlantic thermocline.J. Phys. Oceanogr.,13, 1269–1274.

    Google Scholar 

  53. Sarmiento, J. L., C. G. Rooth and W. Roether (1982): The North Atlantic tritium distribution in 1972.J. Geophys. Res.,87, 8047–8056.

    Google Scholar 

  54. Sarmiento, J. L., G. Thiele, R. M. Key and W. S. Moore (1990): Oxygen and nitrate new production and remineralization in the North Atlantic subtropical gyre.J. Geophys. Res.,95, 18303–18315.

    Google Scholar 

  55. Schlitzer, R. (1988): Modeling the nutrient and carbon cycles of the North Atlantic. 1. Circulation, mixing coefficients and heat fluxes.J. Geophys. Res.,93, 10699–10723.

    Google Scholar 

  56. Schlitzer, R. (1989): Modeling the nutrient and carbon cycles of the North Atlantic. 2. New production, particle fluxes, CO2 gas exchange, and the role of organic nutrients.J. Geophys. Res.,94, 12781–12794.

    Google Scholar 

  57. Smith, L. T., D. B. Boudra and R. Bleck (1990): A wind-driven isopycnic coordinate model of the North and Equatorial Atlantic Ocean. 2. The Atlantic Basin experiments.J. Geophys. Res.,95, 13105–13128.

    Google Scholar 

  58. Stefánsson, U. and L. P. Atkinson (1971): Nutrient-density relationships in the western North Atlantic between Cape Lookout and Bermuda.Limnol. Oceanogr.,16, 51–59.

    Google Scholar 

  59. Stommel, H. (1979): Determination of water mass properties of water pumped down from the Ekman layer to the geostrophic flow below.Proc. Natl. Acad. Sci. USA,76, 3051–3055.

    Google Scholar 

  60. Talley, L. D. and M. S. McCartney (1982): Distribution and circulation of Labrador Sea Water.J. Phys. Oceanogr.,12, 1189–1205.

    Google Scholar 

  61. Thiele, G. and J. L. Sarmiento (1990): Tracer dating and ocean ventilation,J. Geophys. Res.,95, 9377–9391.

    Google Scholar 

  62. Tsuchiya, M. (1968):Upper Waters of the Intertropical Pacific Ocean, Vol. 4. The Johns Hopkins Oceanographic Studies, Johns Hopkins University Press, Baltimore, 50 pp.

    Google Scholar 

  63. Veronis, G. (1988): Circulation driven by winds and surface cooling.J. Phys. Oceanogr.,18, 1920–1932.

    Google Scholar 

  64. Worthington, L. V. (1976):On the North Atlantic Circulation, Vol. 6. The Johns Hopkins Oceanographic Studies, Johns Hopkins University Press, Baltimore, 110 pp.

    Google Scholar 

  65. Yentsch, C. S. (1974): The influence of geostrophy on primary production.Thetys,6, 111–118.

    Google Scholar 

  66. Yoder, J. A., L. A. Atkinson, S. S. Bishop, E. E. Hofmann and T. N. Lee (1983): Effect of upwelling on phytoplankton productivity of the outer southeastern United States continental shelf.Cont. Shelf Res.,1, 385–404.

    Google Scholar 

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Pelegrí, J.L., Csanady, G.T. & Martins, A. The North Atlantic nutrient stream. J Oceanogr 52, 275–299 (1996). https://doi.org/10.1007/BF02235924

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Keywords

  • Mixed Layer
  • Late Spring
  • Western Boundary
  • Principal Factor
  • Gulf Stream