Hydraulic Processes in the Samoan Passage

We just got funded by NSF to study abyssal hydraulic processes in the Samoan Passage. The project will heavily build upon data collected in the Samoan Passage Abyssal Mixing Experiment. In addition, we are planning on running a suite of numerical models spanning from idealized 2D to high-resolution 3D runs that will be tuned to observed turbulent mixing. This dataset will help us identify and study a number of processes that are loosely termed hydraulic - they arise when bottom topography restricts the free flow of the bottom current. Hydraulic processes may cause and alter turbulent mixing of the abyssal current with ambient water and impose restrictions on the maximum flow through the Samoan Passage.

Present theory is unable to account for a number of hydraulic aspects that let the flow through Samoan Passage stand out. Among these are flow through connecting channels, flow through channels with two sill configurations and flow across sills with complex bathymetry. Getting a handle on these processes will be important for better understanding the large scale circulation of the Pacific Ocean as the Samoan Passage is the major supplier for deep water renewal in the North Pacific. Moreover, these configurations are by no means unique to the flow through Samoan Passage and a better knowledge of hydraulic processes here will inform research of the flow at many other canyons and fracture zones of the world’s oceans.