Climate of the Past Discussions www.clim-past-discuss.net 1814-9340 1814-9359 5 3 2009 10.5194/cpd-5-1553-2009 http://www.clim-past-discuss.net/5/1553/2009/ http://www.clim-past-discuss.net/5/1553/2009/cpd-5-1553-2009.html http://www.clim-past-discuss.net/5/1553/2009/cpd-5-1553-2009.pdf 1553 1607 2009-06-03 Variations in mid-latitude North Atlantic surface water properties during the mid-Brunhes: Does Marine Isotope Stage 11 stand out? A. H. L. Voelker T. Rodrigues R. Stein J. Hefter K. Billups D. Oppo J. McManus J. O. Grimalt Dept. Geologia Marinha, Laboratorio Nacional de Energia e Geologia (LNEG; ex-INETI), Estrada da Portela, Zambujal, 2721-866 Alfragide, Portugal CIMAR Associate Laboratory, Rua dos Bragas 289, 4050–123 Porto, Portugal Alfred-Wegener-Institute for Polar and Marine Research, Columbusstrasse, 27568 Bremerhaven, Germany College of Marine and Earth Studies, University of Delaware, 700 Pilottown Road, Lewes, DE 19958, USA Geology and Geophysics, Woods Hole Oceanographic Inst., Woods Hole, MA 02543, USA Department of Environmental Chemistry, Institute of Chemical and Environmental Research (CSIC), Jordi Girona 18, 08034-Barcelona, Spain now at: Department of Earth and Environmental Science, Columbia University, Lamont-Doherty Earth Observatory, 61 Route 9W, Palisades, NY 10964--8000, USA New planktonic stable isotope and ice-rafted debris records from three core sites in the mid-latitude North Atlantic (IODP Site U1313, MD01-2446, MD03-2699) are combined with records of ODP Sites 1056/1058 and 980 to reconstruct hydrographic conditions during the middle Pleistocene spanning Marine Isotope Stages (MIS) 9–14 (300–540 ka). Together the study sites reflect western and eastern basin boundary currents as well as north to south transect sampling of subpolar and transitional water masses. Planktonic δ¹⁸O records indicate that during peak interglacial MIS 9 and 11 hydrographic conditions were similar among all the sites with relative stable conditions and confirm prolonged warmth during MIS 11c also for the mid-latitudes. Sea surface temperature (SST) reconstructions further reveal that in the mid-latitude North Atlantic MIS 11c is associated with two plateaus, the younger one of which is slightly warmer. Enhanced subsurface northward heat flux in the eastern boundary current system, especially during early MIS 11c, is denoted by the presence of tropical planktonic foraminifer species. MIS 13 was generally colder and more variable than the younger interglacials. The greatest differences between the sites existed during the glacial inceptions and glacials. 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