Two modes of glacial climate during the late stage 5 identified in Greenland ice core records
M.-L. Siggaard-Andersen1,2, P. D. Ditlevsen1, A. Walløe Hansen1, and S. J. Johnsen11The Niels Bohr Institute, University of Copenhagen, Juliane Maries Vej 30, 2100 Copenhagen Ø, Denmark 2Alfred Wegener Institute for Polar and Marine Research, Columbusstrasse, 27568, Bremerhaven
Received: 24 Jan 2007 – Discussion started: 02 Feb 2007
Abstract. From a detailed analysis of marine and terrestrial aerosol tracers in the NGRIP ice core we identified two distinct glacial atmospheric flow patterns. The climate transition from Marine Isotope Stage 5 (MIS 5) to MIS 4, at approximately 75 kyr BP, marks a shift between two different atmospheric flow regimes. Before this transition, during MIS 5d-a, the state of atmospheric flow was alternating between the two modes of different flow patterns, while a more persistent flow pattern was prevailing through the glacial period afterwards. These changes are accompanied by strong changes in an independent Greenland ice core proxy, namely the deuterium excess from the GRIP ice core, reflecting changes in the hydrological cycle and moisture source temperatures as well. The changes in atmospheric flow pattern are correlated with changed extent of ice-rafted detritus (IRD) deposition in the North Atlantic, indicating that the state of the atmospheric flow was highly sensitive to the waxing and waning of the Laurentide ice sheet.
Siggaard-Andersen, M.-L., Ditlevsen, P. D., Walløe Hansen, A., and Johnsen, S. J.: Two modes of glacial climate during the late stage 5 identified in Greenland ice core records, Clim. Past Discuss., 3, 285-299, doi:10.5194/cpd-3-285-2007, 2007.