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Bahr, André; Nürnberg, Dirk; Karas, Cyrus; Gruetzner, Jens (2013): Analyses of benthic and planktonic foraminifera during Marine Isotope Stage 5 of ODP Hole 172-1058C. PANGAEA, https://doi.org/10.1594/PANGAEA.818235, Supplement to: Bahr, A et al. (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, 77-87, https://doi.org/10.1016/j.gloplacha.2013.08.013

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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 these warm and saline water likely contributed to the fast resumption of the overturning circulation at the end of these high latitude cold events.
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Coverage:
Latitude: 31.689750 * Longitude: -75.430000
Date/Time Start: 1997-03-01T06:55:00 * Date/Time End: 1997-03-01T06:55:00
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9 datasets

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Datasets listed in this publication series

  1. Bahr, A; Nürnberg, D; Karas, C et al. (2013): Chronostratigraphy for MIS 1-2 and MIS 5 of ODP Hole 172-1058C. https://doi.org/10.1594/PANGAEA.818211
  2. Bahr, A; Nürnberg, D; Karas, C et al. (2013): δ¹⁸O and δ¹³C obtained on Cibicides wuellerstorfi of ODP Hole 172-1058C. https://doi.org/10.1594/PANGAEA.818203
  3. Bahr, A; Nürnberg, D; Karas, C et al. (2013): Planktonik δ¹⁸O and 13C of Globigerinoides ruber white from ODP Hole 172-1058C. https://doi.org/10.1594/PANGAEA.818222
  4. Bahr, A; Nürnberg, D; Karas, C et al. (2013): Planktonik δ¹⁸O and 13C of Globorotalia truncatulinoides sinistral from ODP Hole 172-1058C. https://doi.org/10.1594/PANGAEA.818223
  5. Bahr, A; Nürnberg, D; Karas, C et al. (2013): δ¹⁸O and δ¹³C obtained on Uvigerina peregrina of ODP Hole 172-1058C. https://doi.org/10.1594/PANGAEA.818206
  6. Bahr, A; Nürnberg, D; Karas, C et al. (2013): Computed δ¹⁸Oseawater and d18Oivf-sw (ice volume-free seawater) of ODP Hole 172-1058C, obtained on Globigerinoides ruber white. https://doi.org/10.1594/PANGAEA.818216
  7. Bahr, A; Nürnberg, D; Karas, C et al. (2013): Computed δ¹⁸Oseawater and d18Oivf-sw (ice volume-free seawater) of ODP Hole 172-1058C, obtained on Globorotalia truncatulinoides sinistral. https://doi.org/10.1594/PANGAEA.818217
  8. Bahr, A; Nürnberg, D; Karas, C et al. (2013): Mg/Ca-temperatures of planktonic foraminifer Globigerinoides ruber white from ODP Hole 172-1058C. https://doi.org/10.1594/PANGAEA.818225
  9. Bahr, A; Nürnberg, D; Karas, C et al. (2013): Mg/Ca-temperatures of planktonic foraminifer Globorotalia truncatulinoides sinistral from ODP Hole 172-1058C. https://doi.org/10.1594/PANGAEA.818233