Preprints
https://doi.org/10.5194/tc-2020-353
https://doi.org/10.5194/tc-2020-353

  16 Dec 2020

16 Dec 2020

Review status: this preprint is currently under review for the journal TC.

PISM-LakeCC: Implementing an adaptive proglacial lake boundary into an ice sheet model

Sebastian Hinck1, Evan J. Gowan1,2, Xu Zhang1,3, and Gerrit Lohmann1,2 Sebastian Hinck et al.
  • 1Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research, Am Handelshafen 12, 27570 Bremerhaven, Germany
  • 2MARUM - Center for Marine Environmental Sciences, University Bremen, Leobener Strasse 8, 28359 Bremen, Germany
  • 3College of Earth and Environmental Science, Center for Pan-Third Pole Environment, Lanzhou University, 222 Tianshui South Road, Lanzhou City, China

Abstract. Geological records show that vast proglacial lakes existed along the land terminating margins of palaeo ice sheets in Europe and North America. Proglacial lakes impact ice sheet dynamics by imposing marine-like boundary conditions at the ice margin. These lacustrine boundary conditions include changes in the ice sheet’s geometry, stress balance and frontal ablation and therefore affect the entire ice sheet’s mass balance. This interaction, however, has not been rigorously implemented in ice sheet models. In this study, the implementation of an adaptive lake boundary into the Parallel Ice Sheet Model (PISM) is described and applied to the glacial retreat of the Laurentide Ice Sheet (LIS). The results show that the presence of proglacial lakes locally enhances the ice flow. Along the continental ice margin, ice streams and ice lobes can be observed. Lacustrine terminating ice streams cause immense thinning of the ice sheet’s interior and thus play a significant role in the demise of the LIS. Due to the presence of lakes, a process similar to the marine ice sheet instability causes the collapse of the ice saddle over Hudson Bay, which blocked drainage via the Hudson Strait. In control experiments without a lake model, Hudson Bay is still glaciated at the end of the simulation. Future studies should target the development of parametrizations that better describe the glacial-lacustrine interactions.

Sebastian Hinck et al.

 
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Sebastian Hinck et al.

Sebastian Hinck et al.

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Short summary
Proglacial lakes were pervasive along the retreating continental ice margins after the last glacial maximum. Similarly to the marine ice boundary, interactions at the ice-lake interface impact the ice sheet dynamics and mass balance. Previous numerical ice sheet modeling studies did not include a dynamical lake boundary. We describe the implementation of an adaptive lake boundary condition into PISM and apply the model to the glacial retreat of the Laurentide ice sheet.