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Efficient Flowline Simulations of Ice Shelf–Ocean Interactions: Sensitivity Studies with a Fully Coupled Model

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  • 1 * Earth System Science Interdisciplinary Center, University of Maryland, College Park, College Park, and Cryospheric Sciences Laboratory, NASA Goddard Space Flight Center, Greenbelt, Maryland
  • | 2 Courant Institute of Mathematical Sciences, New York University, New York, New York
  • | 3 The Pennsylvania State University, DuBois, Pennsylvania
  • | 4 The Pennsylvania State University, University Park, Pennsylvania
  • | 5 Cryospheric Sciences Laboratory, NASA Goddard Space Flight Center, Greenbelt, Maryland
  • | 6 ** British Antarctic Survey, Natural Environment Research Council, Cambridge, United Kingdom
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Abstract

Thermodynamic flowline and plume models for the ice shelf–ocean system simplify the ice and ocean dynamics sufficiently to allow extensive exploration of parameters affecting ice-sheet stability while including key physical processes. Comparison between geophysically and laboratory-based treatments of ice–ocean interface thermodynamics shows reasonable agreement between calculated melt rates, except where steep basal slopes and relatively high ocean temperatures are present. Results are especially sensitive to the poorly known drag coefficient, highlighting the need for additional field experiments to constrain its value. These experiments also suggest that if the ice–ocean interface near the grounding line is steeper than some threshold, further steepening of the slope may drive higher entrainment that limits buoyancy, slowing the plume and reducing melting; if confirmed, this will provide a stabilizing feedback on ice sheets under some circumstances.

Corresponding author address: Ryan Walker, NASA Goddard Space Flight Center, Code 615, 8800 Greenbelt Road, Greenbelt, MD 20771. E-mail: ryan.t.walker@nasa.gov

Abstract

Thermodynamic flowline and plume models for the ice shelf–ocean system simplify the ice and ocean dynamics sufficiently to allow extensive exploration of parameters affecting ice-sheet stability while including key physical processes. Comparison between geophysically and laboratory-based treatments of ice–ocean interface thermodynamics shows reasonable agreement between calculated melt rates, except where steep basal slopes and relatively high ocean temperatures are present. Results are especially sensitive to the poorly known drag coefficient, highlighting the need for additional field experiments to constrain its value. These experiments also suggest that if the ice–ocean interface near the grounding line is steeper than some threshold, further steepening of the slope may drive higher entrainment that limits buoyancy, slowing the plume and reducing melting; if confirmed, this will provide a stabilizing feedback on ice sheets under some circumstances.

Corresponding author address: Ryan Walker, NASA Goddard Space Flight Center, Code 615, 8800 Greenbelt Road, Greenbelt, MD 20771. E-mail: ryan.t.walker@nasa.gov
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