Science & Tech

Hadal Water Column Profiler

Madi Davis

The 11-kilometer depth rated Hadal Water Column Profiler was developed to obtain multidisciplinary measurements of the water in the deep ocean trenches. Trenches deeper than 6,000 meters, also known as the hadal zone after the Greek god of the underworld, account for only 2% of the surface area of the ocean but span 45% of the total depth range of the global ocean. Due largely to the immense pressures at those depths – up to 16,000 pounds per square inch – the hadal zone is amongst the most poorly studied regions on the planet. 

The unique Hadal Water Column Profiler allows repeated vertical profiles of temperature, salinity, density, dissolved oxygen, turbulent microstructure (mixing), horizontal current velocity, and 200 kHz bioacoustic backscatter. It also records video (overlapping the acoustic volume) and has a small 11-bottle water sampler. Importantly, it is capable of making multiple profiles a day, even 2-3 profiles/day to 11 km depth.

The Hadal Water Column Profiler is completely untethered from the ship, which allows other operations to be performed during the sampling cast. Ballast weights are used to make the instrument sink, and once the ballast is released, typically at a set height above the seafloor, the profiler becomes positively buoyant and returns to the surface. Once recovered, the data is downloaded, the ballast replaced, and the water sampler and pressure tolerant battery swapped out.

The Hadal Water Column Profiler was developed at the University of Hawaiʻi at Mānoa in cooperation with Ron Allum Deepsea Services (Australia), the Applied Physics Laboratory of the University of Washington (Seattle), and Rockland Scientific International (Canada). Funding was provided by the W. M. Keck Foundation, which was established in 1954 in Los Angeles by William Myron Keck, founder of The Superior Oil Company. One of the nation’s largest philanthropic organizations, the W. M. Keck Foundation supports outstanding science, engineering, and medical research. 

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Hadal Water Column Profiler At-a-Glance

  • 11,000 Meters
  • 4 meters long, 0.54 meters in diameter  
  • 570 kilograms
  • Temperature, Conductivity (salinity), Dissolved Oxygen, Current velocity, Turbulent mixing, 200 kHz Bioacoustic transducer,  620 TVL NTSC video, and eleven 150 milliliter water samples.
  • The profiler is not tethered to the ship. It descends vertically under its own weight before dropping ballast to return to the surface.
  • Data is recorded internally during deployment and downloaded once the profiler is back on the ship.