Using seismic reflection data to reveal high-resolution structure and pathway of the upper Western Boundary Undercurrent core at Eirik Drift
The method of seismic oceanography was applied to identify fine structure and pathways of the Western Boundary Undercurrent (WBUC) at Eirik Drift, 200 km south of Greenland. Three high-velocity cores of the WBUC were distinguished: a deep core in depths >2600 m which carries Denmark Strait Overflow Water, an upper core in depths between ~1900 and 3000 m transporting Iceland–Scotland Overflow Water, and a split-off of this upper core, which crosses the main crest of Eirik Drift at depths between ~1900 and 2400 m. For the upper WBUC core a detailed analysis of the structure was conducted. The WBUC core has as a domed structure, which changes in style, width and height above seafloor along the lines of the changing topography. We proved not only the influence of the topography on pathway and structure of the WBUC core but also that this information cannot be gained by measuring the overflow waters with discrete CTD stations.
KeywordsWestern Boundary Undercurrent (WBUC) Seismic oceanography Eirik Drift Thermohaline circulation (THC) Labrador Sea North Atlantic Deep Water (NADW)
We are grateful for the support of Captain F. von Staa, his officers and crew during RV Maria S. Merian cruise MSM12/2. We want to thank Cord Papenberg and Dirk Klaeschen for the introduction to seismic unix, the use of their pre-processing algorithms and the code to perform the adaptive subtraction of the estimated direct wave. Further, we want to thank Monika Rhein for supplying the MSM12/3 CTD data. The data collection was funded within the program METEOR/MERIAN provided by the Deutsche Forschungsgemeinschaft (DFG). This work was funded by the DFG under Contract No. Ue 49/12.
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