Improving fracture and damage mechanics representation in the NASA Ice Sheet System Model

Fractures are central to a number of important climate feedbacks in glacier and ice sheet dynamics.  Representation of fractures in glacier and ice sheet models is lacking, however, owing  largely  to  the  computational  complexity  of  representing  discontinuous  fractures  in continuum  models  and  to  the  short  timescales  over  which  fractures  propagate  compared to the long timescales over which the viscous creep of glaciers and ice sheets are typically modeled.   Recent advances  in  continuum  damage  mechanics  have  pointed  a  way  forward for representing the influence of fractures on ice mechanical processes without the need for explicitly including a discontinuity in the model.  Viscous damage models have been applied with some success for representing gradual weakening of ice in areas of high stresses. However, there is a growing recognition that many fracture processes operate over short timescales for which elastic stresses need to be accounted for.  This primary goal of this project is to couple an existing elastic damage mechanics model with the open-source NASA Ice Sheet System Model (ISSM), a large-scale, observationally-driven model for representing the long-time scale dynamics of glaciers and ice sheets.  The resulting coupled model will be applied to study fracture processes that are central to iceberg calving and ice shelf collapse, processes that are poorly represented in the current generation of ice sheet models.  This work will lead to improved representation of fracture processes that may become more common in a warming climate, leading to better predictions of the future glaciological contribution to global sea level rise.

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