Collaborative Research: Exploring the Kermadec Trench --- Residence time, spatial gradients, and insights into ventilation

This project will conduct the first physical oceanography survey of a deep ocean trench, focusing on spatial gradients and potential mechanisms of hadal ventilation in the Kermadec Trench. The observations will be made using two unique and complimentary 11 km depth-rated free-falling systems – the Hadal Water Column Profiler and the Deep Autonomous Profiler – to examine patterns and potential mechanisms of trench ventilation. Observations will include the first direct measurements of hadal turbulent microstructure, the first depth profiles of velocity, and the first examination of physical or biological water column gradients along the length of a trench. The field observations consist of multiple collocated deployments of two unique and complimentary 11 km depth-rated instruments. The Hadal Water Column Profiler measures temperature, conductivity, dissolved oxygen, horizontal current velocity, turbulent microstructure, and sideways looking 200 kHz bio-acoustic backscatter. It also has a video camera and a small trace metal-clean water sampler. The Deep Autonomous Profiler measures temperature, conductivity, and dissolved oxygen, and has a downward looking camera and twenty-four 10-liter bottle water sampler. 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.