Development of an autonomous abyssal turbulence profiler

Turbulent mixing in the deep ocean is a process where swirling ocean currents blend freezing, heavy water from the bottom of the sea with lighter, slightly warmer water from above. This stirring helps distribute heat, oxygen, and nutrients that support global ocean circulation and healthy marine ecosystems. The investigators plan to build an instrument capable of measuring turbulent mixing from the surface to 6000 meters depth in the ocean. This project supports collaboration between the researcher and a commercial partner who manufactures the floats. It also provides training for undergraduate students through 2-month summer internships and train and support several early-career engineers Turbulent mixing in the deep ocean is a fundamental process that drives water-mass transformation throughout the global ocean and, therefore, controls many ocean features, such as sound speed and distributions of heat and salinity. Existing autonomous observing platforms are largely limited to intermediate depths (down to 2000m) and rely primarily on indirect inferences of mixing, leaving the abyssal ocean largely unobserved. The investigators will develop and demonstrate the first fully autonomous, full-depth (up to 6000 m) microstructure-profiling float capable of sustained abyssal bottom boundary layer (BBL) sampling, extending measurements of the vertical and horizontal decay scales of internal tide-driven turbulence made during the Hawaii Ocean Mixing Experiment. This technology will directly measure both diapycnal turbulent fluxes and the processes that redistribute buoyancy away from the BBL, addressing a critical observational gap in deep-ocean science. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.