The Deformational Response of a Viscoelastic Solid Earth Model Coupled to a Thermomechanical Ice Sheet Model
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We apply a coupled thermomechanical ice sheet—self-gravitating viscoelastic solid Earth model (SGVEM), allowing for the dynamic exchange of ice thickness and bedrock deformation, in order to investigate the effect of viscoelastic deformation on ice dynamics and vice versa. In a synthetic glaciation scenario, we investigate the interaction between the ice sheet and the solid Earth deformation, the glacial-isostatic adjustment (GIA), accounting for an atmospheric forcing depending on the ice sheet surface altitude. We compare the results from the coupled model to runs with the common elastic lithosphere/relaxing asthenosphere (ELRA) model, where the lithosphere is represented by a thin plate and the mantle relaxes with one characteristic relaxation time, as well as to a rigid Earth without any deformation. We find that the deformational behaviour of the SGVEM on ice dynamics (i.e. stored ice volume, ice thickness and velocity field) is comparable to the ELRA for an optimal choice of the parameters in steady state, but exhibits differences in the transient behaviour. Beyond the ice sheet, in the region of peripheral forebulge, the differences in the transient surface deformation between ELRA and SGVEM are substantial, demonstrating the inadequacy of the ELRA model for interpreting constraints on GIA in the periphery of the ice sheet, such as sea-level indicators and GPS uplift rates.
KeywordsViscoelastic deformation Glacial-isostatic adjustment Thermomechanical ice sheet model Peripheral forebulge
We thank two anonymous referees for their attentive work and Jürgen Kusche for editing the manuscript. HK and IS are funded by the Deutsche Forschungsgemeinschaft (DFG) through Grant SA 1734/2-2, VK through Grant KL 2284/1-3, both within the framework of the DFG priority program SPP1257 ‘Mass transport and mass distribution in the Earth system’. This work is a contribution to the Helmholtz Climate Initiative REKLIM, a joint research project of the Helmholtz Association of German Research Centres (HGF).
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