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doi:10.2204/iodp.proc.303306.109.2006

Part B: Installation of a CORK close to ODP Site 642 to document and monitor bottom water temperature variations through time

Introduction

The northern North Atlantic is the primary deep ventilator of the oceans, and it is now recognized that production of deep water in the northern North Atlantic is intimately related to the global climate (Broecker, 1987; Dickson, 1997; Wood et al., 1999). Changes in the production of NADW may be the result of, or lead to, regional or global climatic changes. Unfortunately there is a lack of long-term observations, and those that do extend back in time are concentrated at the surface or near-surface. Hydrographic time series from the North Atlantic, though sparse and sporadic, show natural variability on timescales of decades to centuries (Wunsch, 1992). In the deep ocean the few observations that do exist show variability on similar timescales and at large spatial scales. Oceanographic observations indicate that the thermohaline structure of the North Atlantic has changed over the past 20 to 30 y, indicating the presence of significant variations in bottom water temperature (BWT) (Roemmich and Wunsch, 1984; Antonov, 1993).

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