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Topographic and surface mass balance controls on Greenland glacier dynamics in a coupled ice-sediment model
(she/her),University of Texas at Austin Austin , United States. email@example.com
Ginny Catania, University of Texas at Austin Austin Texas, United States.
Benjamin Keisling, University of Texas at Austin Austin Texas, United States.
Douglas Brinkerhoff, University of Montana Missoula Montana, United States.
John Christian, Georgia Institute of Technology Atlanta Georgia, United States.
Sean Gulick, University of Texas at Austin Austin Texas, United States.
Moraines in marine-terminating outlet glacier settings can provide a feedback mechanism for glacier stability or retreat, however, sedimentation dynamics in Greenland are poorly understood. With limited observations, sedimentation contributes to the large uncertainty of ice dynamics in estimating Greenland’s future sea level potential. Recent attempts to couple ice and sedimentation show the importance to include moraine-building processes. To advance our understanding, it is necessary to quantify the impact of sedimentation in Greenland outlet glacier settings on different timescales. We explore the sensitivity of Greenland outlet glaciers to sedimentation dynamics including sediment diffusion (removing sediment from moraines) and glaciofluvial sedimentation (adding sediment to moraines) in a flowline model adapted from Brinkerhoff et al., 2017. We run an ensemble of simulations to investigate these processes on 20 kyr timescales, using different bed topography slopes, surface mass balance scenarios, and with sedimentation coupling turned on versus off. We compare across simulations with parameters like ice volume, sediment volume, ice velocity, and bed topography profiles. We find that sedimentation has a strong control on ice volume change and creates tide water glacier cycles with changes in amplitude over time. In addition, we determine the sensitivity of the tide water glacier cycle to variations in bed topography and surface mass balance. The coupling between sediment and ice dynamics could explain and contribute to the divergent glacier behavior presently seen in Greenland outlet glaciers. This work is important for ice sheet model development and field work efforts to understand the rates and processes driving sedimentation in Greenland.