The Western Boundary Undercurrent (WBUC) is a crucial component of the global ocean conveyor belt and is driven by deep water formation (DWF) in the Greenland, Labrador, Norwegian and Iceland Seas. Its path and strength are affected by changing climate conditions and tectonic events (Müller-Michaels and Uenzelmann-Neben, 2014, 2015) which are recorded in the sediments of Eirik Drift, south of Greenland. Seismic profiles and ODP Leg Site 646 and IODP Expedition 303 Sites U1305-U1307 drill cores give information about sedimentation rate and grain sizes since the late Miocene and the Pliocene. Both the late Miocene and Pliocene climates are similar to possible future anthropogenically modified climates and therefore have attracted numerous numerical and proxy-based studies. In this study we will link modifications in sedimentation rates and grain sizes recorded in the cores from Sites 646 and U1305-1307 to climatic and tectonically forced alterations of flowpaths and velocities of the WBUC.
We will simulate ocean dynamics and sediment transports with the Regional Ocean Modeling System (ROMS) in the North Atlantic. The regionalization enables us to run several simulations at unusually high resolution and resolve the WBUC in time and space. The simulated region will encompass the North Atlantic, Labrador Sea, Norwegian Sea, Iceland Sea and Greenland Sea, thereby including all areas of deep water formation of importance for Eirik Drift. Quantitative comparisons between simulated and measured (i.e., reconstructed) sediment transports of the WBUC will be possible for the first time. Derived physical causalities will link variations in sedimentation rate, sediment transports and grain sizes to climate or tectonic changes. Furthermore, the origin of the sediments and the transporting water masses can be determined.
The project is funded for the period 2018 - 2021 by Deutsche Forschungsgemeinschaft (DFG) in the Priority Program SPP 527 "International Ocean Discovery Program", project "Transport, Removal and Accumulation of sediments Numerically Simulated for Paleo-Oceans and Reconstructed from cores of The Eirik Drift (TRANSPORTED)".
Funding: DFG - German Research Foundation