Abstract
Though critically important in sustaining the ocean's biological pump, the cycling of nutrients in the subtropical gyres is poorly understood. The supply of nutrients to the sunlit surface layer of the ocean has traditionally been attributed solely to vertical processes. However, horizontal advection may also be important in establishing the availability of nutrients. Here we show that the production and advection of North Atlantic Subtropical Mode Water introduces spatial and temporal variability in the subsurface nutrient reservoir beneath the North Atlantic subtropical gyre. As the mode water is formed, its nutrients are depleted by biological utilization. When the depleted water mass is exported to the gyre, it injects a wedge of low-nutrient water into the upper layers of the ocean. Contrary to intuition, cold winters that promote deep convective mixing and vigorous mode water formation may diminish downstream primary productivity by altering the subsurface delivery of nutrients.
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References
Mann, K. H. & Lazier, J. R. N. Dynamics of Marine Ecosystems (Blackwell Science, Cambridge, Massachusetts, 1996)
Lewis, M. R., Harrison, W. G., Oakey, N. S., Hebert, D. & Platt, T. Vertical nitrate fluxes in the oligotrophic ocean. Science 234, 870–873 (1986)
Menzel, D. W. & Ryther, J. H. Annual variations in primary productivity of the Sargasso Sea off Bermuda. Deep-Sea Res. I 7, 282–288 (1961)
Gruber, N., Keeling, C. D. & Bates, N. R. Interannual variability in the North Atlantic Ocean carbon sink. Science 298, 2374–2378 (2002)
Lewis, M. R., Kuring, N. & Yentsch, C. Global patterns of ocean transparency: Implications for the new production of the open ocean. J. Geophys. Res. 93, 6847–6856 (1988)
McGillicuddy, D. J. & Robinson, A. R. Eddy-induced nutrient supply and new production in the Sargasso Sea. Deep-Sea Res. I 44, 1427–1450 (1997)
Oschlies, A. & Garcon, V. Eddy-induced enhancement of primary production in a model of the North Atlantic Ocean. Nature 394, 266–269 (1998)
Sarmiento, J. L., Gruber, N., Brzezinski, M. A. & Dunne, J. P. High-latitude controls of thermocline nutrients and low latitude biological productivity. Nature 427, 56–60 (2004)
Talley, L. D. & Raymer, M. E. Eighteen Degree Water variability. J. Mar. Res. 40(suppl.), 757–775 (1982)
McCartney, M. S. The subtropical recirculation of Mode Waters. J. Mar. Res. 40, 427–464 (1982)
Worthington, L. V. On the North Atlantic Circulation (Johns Hopkins University Press, Baltimore, Maryland, 1976)
Siegel, D. A., Doney, S. C. & Yoder, J. A. The North Atlantic spring phytoplankton bloom and Sverdrup's critical depth hypothesis. Science 296, 730–733 (2002)
Pelegrí, J. L. & Csanady, G. T. Nutrient transport and mixing in the Gulf Stream. J. Geophys. Res. 96, 2577–2583 (1991)
Joyce, T., Deser, C. & Spall, M. A. The relation between decadal variability of subtropical mode water and the North Atlantic Oscillation. J. Clim. 13, 2550–2569 (2000)
Talley, L. D. North Atlantic circulation and variability, reviewed for the CNLS conference. Physica D 98, 625–646 (1996)
Dickson, R., Lazier, J., Meincke, J., Rhines, P. & Swift, J. Long-term coordinated changes in the convective activity of the North Atlantic. Prog. Oceanogr. 38, 241–295 (1996)
McClain, C. R., Signorini, S. R. & Christian, J. R. Subtropical gyre variability observed by ocean-colour satellites. Deep-sea Res. II 51, 281–301 (2004)
Williams, R. G. & Follows, M. J. The Ekman transfer of nutrients and maintenance of new production over the North Atlantic. Deep-Sea Res. I 45, 461–489 (1998)
McGillicuddy, D. J. et al. Influence of mesoscale eddies on new production in the Sargasso Sea. Nature 419, 263–266 (1998)
Fratantoni, D. M. North Atlantic surface circulation during the 1990's observed with satellite-tracked drifters. J. Geophys. Res. 106, 22067–22093 (2001)
Wilson, C. & Adamec, D. A global view of bio-physical coupling from SeaWIFS and TOPEX satellite data, 1997–2001. Geophys. Res. Lett. 29,doi:10.1029/2001GL014063 (2002)
Bahamón, N., Velasquez, Z. & Cruzado, A. Chlorophyll a and nitrogen flux in the tropical North Atlantic Ocean. Deep-Sea Res. I 50, 1189–1203 (2003)
Fitzwater, S., Knauer, G. A. & Martin, J. H. Metal contamination and its effect on primary production measurements. Limnol. Oceanogr. 27, 544–551 (1982)
Barber, R. T. et al. Primary productivity and its regulation in the Arabian Sea during 1995. Deep-Sea Res. II 48, 1127–1172 (2001)
Trenberth, K. E., Olsen, J. G. & Large, W. G. A Global Ocean Wind Stress Climatology Based on ECMWF Analyses (Tech. Note NCAR/TN-338 + STR, National Center for Atmospheric Research, Boulder, Colorado, 1989)
Kara, A. B., Rochford, P. A. & Hurlburt, H. E. Mixed layer depth variability over the global ocean. J. Geophys. Res. 108, doi:10.1029/2000JC000736 (2003)
Lozier, M. S., Owens, W. B. & Curry, R. G. The climatology of the North Atlantic. Prog. Oceanogr. 36, 1–44 (1995)
Takahashi, T., Broecker, W. S. & Langer, S. Redfield ratio based on chemical data from isopycnal surfaces. J. Geophys. Res. 90, 6907–6924 (1985)
Walker, S. J., Weiss, R. F. & Salameh, P. K. Reconstructed histories of the annual mean atmospheric mole fractions for the halocarbons CFC-11, CFC-12, CFC-113, and carbon tetrachloride. J. Geophys. Res. 105, 14285–14296 (2000)
Warner, M. J. & Weiss, R. F. Solubilities of chlorofluorocarbons 11 and 12 in water and seawater. Deep-Sea Res. I 32, 1485–1497 (1985)
Ledwell, J. R., Watson, A. J. & Law, C. S. Evidence for slow mixing across the pycnocline from an open-ocean tracer-release experiment. Nature 364, 701–703 (1993)
Jenkins, W. J. Oxygen utilization rates in North Atlantic subtropical gyre and primary production in oligotrophic systems. Nature 300, 246–248 (1982)
Acknowledgements
We thank P. Lethaby for the Hydrostation S data, D. Fratantoni for the EKE data, and D. LaBel and W. Smethie for the CFC age data. This Article also benefited from discussions with M. Follows and W. Jenkins. This work was supported by an NSF Graduate Research Fellowship.
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Supplementary Figure S1
Nitrate, CFC age and PV for WOCE sections A20 and A22 in 1997. (PDF 1146 kb)
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Palter, J., Lozier, M. & Barber, R. The effect of advection on the nutrient reservoir in the North Atlantic subtropical gyre. Nature 437, 687–692 (2005). https://doi.org/10.1038/nature03969
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DOI: https://doi.org/10.1038/nature03969