Seaglider and Float Observations Beneath Dotson Ice Shelf, West Antarctica

Pierre Dutrieux, Lamont-Doherty Earth Observatory, Palisades, NY, United States, Craig Lee, Univ Washington, Seattle, United States, Luc Rainville, University of Washington, Seattle, United States, Jason I Gobat, University of Washington, Seattle, WA, United States, James B Girton, Applied Physics Laboratory, University of Washington, Seattle, WA, United States, Knut A Christianson, University of Washington, Earth and Space Sciences, Seattle, WA, United States, Tae-Wan Kim, KOPRI Korea Polar Research Institute, Incheon, South Korea, SangHoon Lee, KOPRI Korea Polar Research Institute, Incheon, Korea, Republic of (South) and Romain Millan, University of Grenoble Alpes, Grenoble, France
In Antarctica and Greenland, interactions between Oceans and Ice sheets are crucial to the regulation of the global overturning circulation and the current acceleration of ice flow into the ocean and associated global sea-level rise. Satellite and moored ocean observations demonstrate with increasing temporal and spatial resolution that the interaction is complex, and occurs on broad ranges of scales. But the establishment of clear relationships between ocean and ice sheet will remain elusive until we obtain direct, sustained in-situ observations beneath and near the ice shelves. Three Seagliders and four EM-APEX floats sampled oceanic properties near and under the Dotson ice shelf in West Antarctica in January 2018, with observations continuing through the winter into summer 2018/2019, covering several hundreds of kilometers under the ice shelf. Observed water properties generally confirm expected features of under ice shelf circulation, with deep inflowing warmer water on the eastern side of the cavity and shallower outflowing meltwater on the western side. Initial analysis also reveal new and potentially important features for ice/ocean interactions: (i) bathymetric inversion from airborne gravity observations are significantly improved by using in-situ constraints; (ii) large intraseasonal and seasonal variability along the ice shelf calving front, of the order of the interannual variability shown previously, is rapidly transferred inside the cavity; and (iii) a float slipped through a wide gap between Dotson and Crosson ice cavities, implying broader connectivity between basins, and potential implications for ice dynamics. The technology used for this project offers tantalizing prospects for future explorations.