The development of the Western Boundary Undercurrent (WBUC) in a changing climate since the beginning of the Miocene

• Main Authors: Mueller-Michaelis, Antje, Uenzelmann-Neben, Gabriele
• Format: Conference Object
• Language: unknown
• Published: 2013
• Subjects: Denmark Strait; Greenland; Greenland Sea; Greenland-Scotland Ridge; Iceland; North Atlantic; North atlantic Thermohaline circulation
• Online Access: https://epic.awi.de/id/eprint/32221/; https://hdl.handle.net/10013/epic.40856

The present deep Western Boundary Undercurrent (WBUC) at the Eirik Drift off the southern tip of Greenland is mainly fed by the overflows over the Greenland-Scotland ridge (GSR), the Denmark Strait Overflow Water (DSOW) and Iceland-Scotland Overflow Water (ISOW), respectively (Fig. 1). Interactions of the atmosphere with the warm and saline Atlantic surface inflow to the Norwegian-Greenland Sea (NGS) yield in convective mixing and the production of these dense overflow water masses (Van Aken, 2007). Therefore, the WBUC at the Eirik Drift is sensitive to changes in the deep-water formation and hence, to climate changes. Changes in the WBUC will, in turn, affect the world's climate. The WBUC is the main contributor to the lower branch of the North Atlantic Thermohaline Circulation (THC). The upper counterpart of the THC is responsible for the global redistribution of heat and freshwater via the surface ocean. The Eirik Drift has been shaped by the WBUC since the Miocene. It therefore archives information of changes in depositional processes and hence, changes in the pathways and strength of the WBUC. The high-resolution multichannel seismic reflection data network collected during RV Maria S. Merian cruise MSM 12/2 crossed ODP Leg 105 Site 646 and IODP Expedition 303 Sites U1305, U1306, and U1307 (Fig. 1). Thus, the seismic reflection data could be incorporated with geological information from the ODP and IODP sites (Channell et al., 2010; Srivastava et al., 1989) to deduce information on the development of the WBUC and a much clearer understanding of the evolution of the climate in the northern North Atlantic during the Neogene. Synthetic seismograms based on density and P-wave velocity data from ODP Leg 105 Site 646 and IODP Expedition 303 Sites U1305, U1306, and U1307 were correlated with the processed seismic reflection data. We identified four seismic units and the reflectors defined by Arthur et al. (1989) and refined the stratigraphy by horizons A1 (0.8 Ma), A2 (1.4 Ma) and A3 (19-17 Ma) (Table 1). We ...