• Browse
    • Author
    • Year
    • Platform
    • Organizations
    • Programs
    • Research Networks
    • Type
  • Search
    • Simple
    • Advanced
  • About
    • About
    • Policies
    • Citation Guide
  • Login
    Logo Alfred Wegener Institut
    Logo Alfred Wegener Institut
    Alfred-Wegener-Institut
    Helmholtz-Zentrum für Polar-
    und Meeresforschung
    • Imprint
    • Contact
    • OAI
    • RSS 2.0

    EPIC.awi.de

    Home
    • Browse
      • Author
      • Year
      • Platform
      • Organizations
      • Programs
      • Research Networks
      • Type
    • Search
      • Simple
      • Advanced
    • About
      • About
      • Policies
      • Citation Guide
    • Login
      Login

      Millennial-scale versus long-term dynamics in the surface and subsurface of the western North Atlantic Subtropical Gyre during Marine Isotope Stage 5

      Edit Item Edit Item

      General Information:

      Citation:
      Bahr, A. , Nürnberg, D. , Karas, C. and Gruetzner, J. (2013): Millennial-scale versus long-term dynamics in the surface and subsurface of the western North Atlantic Subtropical Gyre during Marine Isotope Stage 5 , Global and Planetary Change, 111 , pp. 77-87 . doi: 10.1016/j.gloplacha.2013.08.013
      Cite this page as:
      hdl:10013/epic.42647
      DOI:
      https://doi.org/10.1016/j.gloplacha.2013.08.013
      Official URL:
      http://www.sciencedirect.com/science/article/pii/S0921818113001847
      Contact Email:
      a.bahr@em.uni-frankfurt.de
      Related Data:

      Abstract:

      Subtropical Gyres are an important constituent of the ocean–atmosphere system due to their capacity to store vast amounts of warm and saline waters. Here we decipher the sensitivity of the (sub)surface North Atlantic Subtropical Gyre with respect to orbital and millennial scale climate variability between ~ 140 and 70 ka, Marine Isotope Stage (MIS) 5. Using (isotope) geochemical proxy data from surface and thermocline dwelling foraminifers from Blake Ridge off the west coast of North America (ODP Site 1058) we show that the oceanographic development at subsurface (thermocline) level is substantially different from the surface ocean. Most notably, surface temperatures and salinities peak during the penultimate deglaciation (Termination II) and early MIS 5e, implying that subtropical surface ocean heat and salt accumulation might have resulted from a sluggish northward heat transport. In contrast, maximum thermocline temperatures are reached during late MIS 5e when surface temperatures are already declining. We argue that the subsurface warming originated from intensified Ekman downwelling in the Subtropical Gyre due to enhanced wind stress. During MIS 5a-d a tight interplay of the subtropical upper ocean hydrography to high latitude millennial-scale cold events can be observed. At Blake Ridge, the most pronounced of these high latitude cold events are related to surface warming and salt accumulation in the (sub)surface. Similar to Termination II, heat accumulated in the Subtropical Gyre probably due to a reduced Atlantic Meridional Overturning Circulation. Additionally, a southward shift and intensification of the subtropical wind belts lead to a decrease of on-site precipitation and enhanced evaporation, coupled to intensified gyre circulation. Subsequently, the northward advection of this warm and saline water likely contributed to the fast resumption of the overturning circulation at the end of these high latitude cold events.

      Further Details:

      Item Type:
      Article
      Authors:
      Bahr, André ; Nürnberg, Dirk ; Karas, Cyrus ; Gruetzner, Jens
      Divisions:
      AWI Organizations > Geosciences > Geophysics
      Primary Division:
      Organizations > AWI Organizations > Geosciences > Geophysics
      Programs:
      Helmholtz Research Programs > PACES I (2009-2013) > TOPIC 3: Lessons from the Past > WP 3.2: Tectonic, Climate and Biosphere Development from Greenhouse to Icehouse
      Primary Topic:
      Helmholtz Programs > Helmholtz Research Programs > PACES I (2009-2013) > TOPIC 3: Lessons from the Past > WP 3.2: Tectonic, Climate and Biosphere Development from Greenhouse to Icehouse
      Eprint ID:
      34350
      Logo Alfred Wegener Institut
      Alfred-Wegener-Institut
      Helmholtz-Zentrum für Polar-
      und Meeresforschung
      Logo Helmholtz

      • Browse
        • Author
        • Year
        • Platform
        • Organizations
        • Programs
        • Research Networks
        • Type
      • Search
        • Simple
        • Advanced
      • About
        • About
        • Policies
        • Citation Guide
      • Imprint
      • Contact
      • OAI
      © Alfred-Wegener-Institut