"Physics and Mechanics of the Breakup of Warm Antarctic Sea Ice: In-Situ

Experiments and Modeling"

Program Manager Bernhard Lettau

OPP Office of Polar Programs

PI:      John Dempsey, Clarkson University

Co-PI: David Cole US Army CRREL

Abstract

  This project is a study of how the antarctic sea ice cover responds to

  stresses applied by wind and ocean waves, and how the temperature distribution

  within the sea ice affects these responses. Experiments will be conducted on

  the deformation and fracture of warm sea ice in McMurdo Sound in the austral

  Spring by applying a series of controlled stresses and observing their

  effects. It is known that large ice floes are affected by microstructural

  anisotropies, but do not fracture in the same way as small ones do, therefore

  it is necessary to carry out experiments on the scale of tens of meters in

  order to validly extrapolate the fracture process to the larger scales that

  have applications to engineering problems of breaking ice. Crucial elements

  for this study are the obtaining of detailed information on the microstructure

  of the ice, such as crystal structure, brine channels, and other flaws in the

  ice fabric, and having a sound theoretical framework to guide the experimental

  work and subsequent model development. These findings will give important

  insight into the underlying mechanisms of ice breakup and will signi.cantly

  improve the reliability of models of this process. This work will improve the

  understanding of and ability to model the deformation and fracture of

  Antarctic sea ice at scales applicable to the breakup of ice sheets.