Preprints
https://doi.org/10.5194/egusphere-2023-2869
https://doi.org/10.5194/egusphere-2023-2869
14 Dec 2023
 | 14 Dec 2023

FastIsostasy v1.0 – An accelerated regional GIA model accounting for the lateral variability of the solid Earth

Jan Swierczek-Jereczek, Marisa Montoya, Konstantin Latychev, Alexander Robinson, Jorge Alvarez-Solas, and Jerry Mitrovica

Abstract. The vast majority of ice-sheet modelling studies rely on simplified representations of the Glacial Isostatic Adjustment (GIA), which, among other limitations, do not account for lateral variations of the lithospheric thickness and upper-mantle viscosity. In studies using 3D GIA models, this has however been shown to have major impacts on the dynamics of marine-based sectors of Antarctica, which are likely to be the greatest contributors to sea-level rise in the coming centuries. This gap in comprehensiveness is explained by the fact that 3D GIA models are computationally expensive, seldomly open-source and require the implementation of an iterative coupling scheme to converge with the history of the ice-sheet model. To close this gap between "best" and "tractable" GIA models, we here propose FastIsostasy, a regional GIA model capturing lateral variations of the lithospheric thickness and mantle viscosity. By means of Fast-Fourier transforms and a hybrid collocation scheme to solve its underlying partial differential equation, FastIsostasy can simulate 100,000 years of high-resolution bedrock displacement in only minutes of single-CPU computation, including the changes in sea-surface height due to mass redistribution. Despite its 2D grid, FastIsostasy parametrises the depth-dependent viscosity in a physically meaningful way and therefore represents the depth dimension to a certain extent. FastIsostasy is here benchmarked against analytical, 1D and 3D GIA solutions and shows very good agreement with them. It is fully open-source, documented with many examples and provides a straight-forward interface for coupling to an ice-sheet model. The model is benchmarked here based on its implementation in Julia, while a Fortran version is also provided to allow for compatibility with most existing ice-sheet models. The Julia version provides additional features, including a vast library of time-stepping methods and GPU support.

Jan Swierczek-Jereczek, Marisa Montoya, Konstantin Latychev, Alexander Robinson, Jorge Alvarez-Solas, and Jerry Mitrovica

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • CEC1: 'Comment on egusphere-2023-2869', Juan Antonio Añel, 20 Dec 2023
    • AC1: 'Reply on CEC1', Jan Swierczek-Jereczek, 21 Dec 2023
      • CEC2: 'Reply on AC1', Juan Antonio Añel, 22 Dec 2023
  • RC1: 'Comment on egusphere-2023-2869', Anonymous Referee #1, 02 Jan 2024
  • RC2: 'Comment on egusphere-2023-2869', Anonymous Referee #2, 19 Jan 2024
  • RC3: 'Comment on egusphere-2023-2869', Anonymous Referee #3, 26 Jan 2024
  • RC4: 'Comment on egusphere-2023-2869', Caroline van Calcar, 13 Feb 2024
  • AC6: 'Comment on egusphere-2023-2869', Jan Swierczek-Jereczek, 24 Feb 2024
Jan Swierczek-Jereczek, Marisa Montoya, Konstantin Latychev, Alexander Robinson, Jorge Alvarez-Solas, and Jerry Mitrovica
Jan Swierczek-Jereczek, Marisa Montoya, Konstantin Latychev, Alexander Robinson, Jorge Alvarez-Solas, and Jerry Mitrovica

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Short summary
Ice sheets present a thickness of a few kilometres, leading to a vertical deformation of the crust of up to a kilometre. This process depends on properties of the solid Earth, which can be regionally very different. We propose a model that accounts for this often ignored heterogeneity and runs 100,000 simulation years in only minutes. Thus, the evolution of ice sheets is modelled with better accuracy, which is critical for a good mitigation of climate change and, in particular, sea-level rise.