• Aagaard, K., and S-A. Malmberg, 1978: Low-frequency characteristics of the Denmark Strait overflow. ICES CM 1978/C:47, International Council for the Exploration of the Sea, Copenhagen, Denmark, 22 pp.

    • Search Google Scholar
    • Export Citation
  • Baringer, M. O., and J. F. Price, 1997: Momentum and energy balance of the Mediterranean outflow. J. Phys. Oceanogr., 27 , 16781692.

  • Dickson, R. R., and J. Brown, 1994: The production of North Atlantic Deep Water: Sources, rates, and pathways. J. Geophys. Res., 99 , 1231912341.

    • Search Google Scholar
    • Export Citation
  • Dickson, R. R., J. Lazier, J. Meincke, P. Rhines, and J. Swift, 1996: Long-term coordinated changes in the convective activity of the North Atlantic. Progress in Oceanography, Vol. 38, Pergamon, 241–295.

    • Search Google Scholar
    • Export Citation
  • Fristedt, T., R. Hietala, and P. Lundberg, 1999: Stability properties of a barotropic surface-water jet observed in the Denmark Strait. Tellus, 51A , 979989.

    • Search Google Scholar
    • Export Citation
  • Girton, J. B., 2001: Dynamics of transport and variability in the Denmark Strait overflow. Ph.D. thesis, University of Washington, Seattle, WA, 305 pp.

    • Search Google Scholar
    • Export Citation
  • Girton, J. B., and T. B. Sanford, 1999: Velocity profile measurements of the Denmark Strait overflow. International WOCE Newslett., No. 37, WOCE International Project Office, Southampton, United Kingdom, 28–30.

    • Search Google Scholar
    • Export Citation
  • Girton, J. B., T. B. Sanford, and R. H. Käse, 2001: Synoptic sections of the Denmark Strait overflow. Geophys. Res. Lett., 28 , 16191622.

    • Search Google Scholar
    • Export Citation
  • Jiang, L., and R. W. Garwood Jr., 1996: Three-dimensional simulations of overflows on continental slopes. J. Phys. Oceanogr., 26 , 12141233.

    • Search Google Scholar
    • Export Citation
  • Johnson, G. C., and T. B. Sanford, 1992: Secondary circulation in the Faroe Bank Channel outflow. J. Phys. Oceanogr., 22 , 927933.

  • Johnson, G. C., R. G. Lueck, and T. B. Sanford, 1994a: Stress on the Mediterranean outflow plume. Part II: Turbulent dissipation and shear measurements. J. Phys. Oceanogr., 24 , 20842092.

    • Search Google Scholar
    • Export Citation
  • Johnson, G. C., T. B. Sanford, and M. O. Baringer, 1994b: Stress on the Mediterranean outflow plume: Part I. Velocity and water property measurements. J. Phys. Oceanogr., 24 , 20722083.

    • Search Google Scholar
    • Export Citation
  • Jungclaus, J. H., and J. O. Backhaus, 1994: Application of a transient reduced gravity plume model to the Denmark Strait overflow. J. Geophys. Res., 99 , 1237512396.

    • Search Google Scholar
    • Export Citation
  • Jungclaus, J. H., J. Hauser, and R. H. Käse, 2001: Cyclogenesis in the Denmark Strait overflow plume. J. Phys. Oceanogr., 31 , 32143229.

    • Search Google Scholar
    • Export Citation
  • Käse, R. H., and A. Oschlies, 2000: Flow through Denmark Strait. J. Geophys. Res., 105 , 2852728546.

  • Käse, R. H., J. B. Girton, and T. B. Sanford, 2003: Structure and variability of the Denmark Strait overflow: Model and observations. J. Geophys. Res., in press.

    • Search Google Scholar
    • Export Citation
  • Killworth, P. D., 1977: Mixing on the Weddell Sea continental slope. Deep-Sea Res., 24 , 427448.

  • Killworth, P. D., 2001: On the rate of descent of overflows. J. Geophys. Res., 106 , 2226722275.

  • Killworth, P. D., and N. R. Edwards, 1999: A turbulent bottom boundary layer code for use in numerical ocean models. J. Phys. Oceanogr., 29 , 12211238.

    • Search Google Scholar
    • Export Citation
  • Krauss, W., and R. H. Käse, 1998: Eddy formation in the Denmark Strait overflow. J. Geophys. Res., 103 , 1552515538.

  • MacCready, P., and P. B. Rhines, 1993: Slippery bottom boundary layers on a slope. J. Phys. Oceanogr., 23 , 522.

  • Mauritzen, C., 1996: Production of dense overflow waters feeding the North Atlantic across the Greenland–Scotland Ridge. Part 2: An inverse model. Deep-Sea Res., 43A , 807835.

    • Search Google Scholar
    • Export Citation
  • Oakey, N. S., and J. A. Elliott, 1980: The variability of temperature gradient microstructure observed in the Denmark Strait. J. Geophys. Res., 85 , 19331944.

    • Search Google Scholar
    • Export Citation
  • Price, J. F., and M. O. Baringer, 1994: Outflows and deep water production by marginal seas. Progress in Oceanography, Vol. 33, Pergamon, 161–200.

    • Search Google Scholar
    • Export Citation
  • Ross, C. K., 1984: Temperature–salinity characteristics of the “overflow” water in Denmark Strait during “OVERFLOW '73.”. Rapp. P. V. Reun. Cons. Int. Explor. Mer, 185 , 111119.

    • Search Google Scholar
    • Export Citation
  • Rudels, B., P. Eriksson, H. Grönvall, R. Hietala, and J. Launiainen, 1999: Hydrographic observations in Denmark Strait in fall 1997, and their implications for the entrainment into the overflow plume. Geophys. Res. Lett., 26 , 13251328.

    • Search Google Scholar
    • Export Citation
  • Sanford, T. B., and R-C. Lien, 1999: Turbulent properties in a homogeneous tidal bottom boundary layer. J. Geophys. Res., 104 , 12451257.

    • Search Google Scholar
    • Export Citation
  • Smith, P. C., 1975: A streamtube model for bottom boundary currents in the ocean. Deep-Sea Res., 22 , 853873.

  • Smith, P. C., 1976: Baroclinic instability in the Denmark Strait overflow. J. Phys. Oceanogr., 6 , 355371.

  • Smith, W. H. F., and D. T. Sandwell, 1997: Global sea floor topography from satellite altimetry and ship depth soundings. Science, 277 , 19561962.

    • Search Google Scholar
    • Export Citation
  • Stahr, F. R., and T. B. Sanford, 1999: Transport and bottom boundary layer observations of the North Atlantic Deep Western Boundary Current at the Blake Outer Ridge. Deep-Sea Res., 46B , 205243.

    • Search Google Scholar
    • Export Citation
  • Swaters, G. E., 1991: On the baroclinic instability of cold-core coupled density fronts on a sloping continental shelf. J. Fluid Mech., 224 , 361382.

    • Search Google Scholar
    • Export Citation
  • Turner, J. S., 1986: Turbulent entrainment: The development of the entrainment assumption, and its application to geophysical flows. J. Fluid Mech., 173 , 431471.

    • Search Google Scholar
    • Export Citation
  • Worthington, L. V., 1969: An attempt to measure the volume transport of Norwegian Sea overflow water through the Denmark Strait. Deep-Sea Res., 16 , 421432.

    • Search Google Scholar
    • Export Citation
  • Zilitinkevich, S., and D. V. Mironov, 1996: A multi-limit formulation for the equilibrium depth of a stably stratified boundary layer. Bound.-Layer Meteor., 81 , 325351.

    • Search Google Scholar
    • Export Citation
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Descent and Modification of the Overflow Plume in the Denmark Strait

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  • 1 Applied Physics Laboratory and School of Oceanography, University of Washington, Seattle, Washington
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Abstract

Bulk properties of the Denmark Strait overflow (DSO) plume observed in velocity and hydrography surveys undertaken in 1997 and 1998 are described. Despite the presence of considerable short-term variability, it is found that the pathway and evolution of the plume density anomaly are remarkably steady. Bottom stress measurements show that the pathway of the plume core matches well with a rate of descent controlled by friction. The estimated entrainment rate diagnosed from the rate of plume dilution with distance shows a marked increase in entrainment at approximately 125 km from the sill, leading to a net dilution consistent with previous reports of a doubling of overflow transport measured by current meter arrays. The entrainment rate increase is likely related to the increased topographic slopes in the region, compounded by a decrease in interface stratification as the plume is diluted and enters a denser background.

Current affiliation: Woods Hole Oceanographic Institution, Woods Hole, Massachusetts

Corresponding author address: James B. Girton, Department of Oceanography, MS 29, WHOI, Woods Hole, MA 02543. Email: girton@whoi.edu

Abstract

Bulk properties of the Denmark Strait overflow (DSO) plume observed in velocity and hydrography surveys undertaken in 1997 and 1998 are described. Despite the presence of considerable short-term variability, it is found that the pathway and evolution of the plume density anomaly are remarkably steady. Bottom stress measurements show that the pathway of the plume core matches well with a rate of descent controlled by friction. The estimated entrainment rate diagnosed from the rate of plume dilution with distance shows a marked increase in entrainment at approximately 125 km from the sill, leading to a net dilution consistent with previous reports of a doubling of overflow transport measured by current meter arrays. The entrainment rate increase is likely related to the increased topographic slopes in the region, compounded by a decrease in interface stratification as the plume is diluted and enters a denser background.

Current affiliation: Woods Hole Oceanographic Institution, Woods Hole, Massachusetts

Corresponding author address: James B. Girton, Department of Oceanography, MS 29, WHOI, Woods Hole, MA 02543. Email: girton@whoi.edu

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