Towards Development of the High Precision Supercooling Measurement Instrument (“HiPSMI”) for Supercooling Measurements Under Ice Shelves

Inga Smith1, Peter Russell1, Maren E. Richter2, Britney E Schmidt3, Lars Henrik Smedsrud4, Greg H Leonard5, Justin Lawrence6, Ben Hurwitz7, Jonathan R. Everts2 and Matthew Ryan Meister8, (1)University of Otago, Dunedin, New Zealand, (2)University of Otago, Department of Physics, Dunedin, New Zealand, (3)Cornell University, Ithaca, NY, United States, (4)Geophysical Institute, University of Bergen and Bjerknes Centre for Climate Research, Bergen, Norway, (5)University of Otago, School of Surveying, Dunedin, New Zealand, (6)Georgia Institute of Technology Main Campus, Atlanta, GA, United States, (7)Georgia Institute of Technology, School of Earth and Atmospheric Sciences, Atlanta, GA, United States, (8)Cornell University, School of Earth and Atmospheric Sciences, Ithaca, United States
The oceans beneath Antarctic ice shelves are the least measured waters on Earth. Beneath the Antarctic sea ice and ice shelves, sea water is often colder than its freezing point temperature, yet still liquid. Such water is called “supercooled” sea water. Snap-freezing of supercooled sea water and small free-floating ice crystals known as “frazil” are fundamental obstacles to obtaining high-precision measurements of key ocean parameters needed for climate research. In the project “Supercooling measurements under ice shelves”, we will overcome this obstacle by working as an international collaborative team (New Zealand, USA and Norway) to design and construct a new novel instrument; the High Precision Supercooling Measurement Instrument (“HiPSMI”). HiPSMI will be optimised for harsh Antarctic ocean conditions and installed into an innovative, modular underwater robot, “Icefin”. HiPSMI will include high precision temperature and pressure sensors and a pumped electrical conductivity sensor, configured for supercooling measurements . In addition, Icefin will have on-board un-pumped electrical conductivity sensors, possibly including nanotechnology sensors, to allow comparisons with HiPSMI. Observations will be made beneath the sea ice and McMurdo Ice Shelf, Antarctica in October and November 2020. We will determine the influence of frazil crystals on measurements of in situ supercooling. The measurements, in conjunction with numerical modelling and laboratory work, will revolutionise our understanding of supercooled waters by providing a high-precision, observational-based indicator for future climate observations beneath the vast cold cavity ice shelves of Antarctica. Our research will feed into the ocean engineering challenges of the next frontier of polar exploration; ice-covered oceans on other worlds. This project is funded through the New Zealand Marsden Fund’s Engineering and Interdisciplinary Sciences Panel, with a technology-for-observations development focus.