Preprints
https://doi.org/10.5194/gmd-2021-126
https://doi.org/10.5194/gmd-2021-126

Submitted as: development and technical paper 17 May 2021

Submitted as: development and technical paper | 17 May 2021

Review status: a revised version of this preprint is currently under review for the journal GMD.

Capturing the Interactions Between Ice Sheets, Sea Level and the Solid Earth on a Range of Timescales: A new "time window" algorithm

Holly Kyeore Han, Natalya Gomez, and Jeannette Xiu Wen Wan Holly Kyeore Han et al.
  • Department of Earth and Planetary Sciences, McGill University, Montreal, H3A 0G4, Canada

Abstract. Retreat and advance of ice sheets perturb the gravitational field, solid surface and rotation of the Earth, leading to spatially variable sea-level changes over a range of timescales (~O100-6 years), which in turn feed back onto ice sheet dynamics. Coupled ice-sheet – sea-level models have been developed to capture the interactive processes between ice sheets, sea level and the solid Earth, but it is computationally challenging to capture short-term interactions (~O100-2 years) precisely within longer (~O103-6 years) simulations. The classic coupling algorithm assigns a uniform temporal resolution in the sea-level model, causing a quadratic increase in total CPU time with the total number of input ice history steps, which increases with either the length or temporal resolution of the simulation. In this study, we introduce a new “time window” algorithm for sea-level models that enables users to define the temporal resolution at which the ice loading history is captured during different time intervals before the current simulation time. Utilizing the time window, we assign a fine temporal resolution (~O100-2 years) for the period of ongoing and recent history of surface ice and ocean loading changes and a coarser temporal resolution (~O103-6 years) for earlier periods in the simulation. This reduces the total CPU time and memory required per model time step while maintaining the precision of the model results. We explore the sensitivity of sea-level model results to the model's temporal resolution and show how this sensitivity feeds back onto ice sheet dynamics in coupled modelling. We apply the new algorithm to simulate the sea-level changes in response to global ice-sheet evolution over two glacial cycles and the rapid collapse of marine sectors of the West Antarctic Ice Sheet in the coming centuries, providing appropriate time window profiles for each of these applications. The time window algorithm improves the total CPU time by ~50–% in each of these examples, and this improvement would increase with longer simulations than considered here. Our algorithm also allows coupling time intervals of annual temporal scale for coupled ice-sheet – sea-level modelling of regions such as the West Antarctic that are characterized by rapid solid Earth response to ice changes due to the thin lithosphere and low mantle viscosities.

Holly Kyeore Han et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on gmd-2021-126', Wouter van der Wal, 23 Aug 2021
  • RC2: 'Comment on gmd-2021-126', Volker Klemann, 25 Aug 2021
  • EC1: 'Proceed with revisions', Andrew Wickert, 25 Aug 2021
  • AC1: 'Response to Reviewer1's specific comment on gmd-2021-126', Holly Han, 08 Oct 2021
  • AC2: 'Response to Reviewer2's specific comment on gmd-2021-126', Holly Han, 08 Oct 2021
  • AC3: 'Response to Reviewer1&2's general comment on gmd-2021-126',', Holly Han, 08 Oct 2021

Holly Kyeore Han et al.

Data sets

Capturing the Interactions Between Ice Sheets, Sea Level and the Solid Earth on a Range of Timescales: A new “time window” algorithm Holly Kyeore Han, Natalya Gomez, Jeannette Xiu Wen Wan https://osf.io/8ptfm/

Holly Kyeore Han et al.

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Short summary
Interactions between ice sheets, sea level and the solid Earth occur over a range of timescales from years to tens of thousands of years. This requires coupled ice sheet-sea level models to exchange information frequently, leading to a quadratic increase in compute time with the number of model timesteps. We present a new sea-level model algorithm that allows coupled models to improve the computational feasibility and precisely capture short-term interactions within longer simulations.