Biological and Environmental Research - Earth and Environmental System Sciences
Earth and Environmental System Modeling

Diagnosing the sensitivity of grounding-line flux to changes in sub-ice-shelf melting

TitleDiagnosing the sensitivity of grounding-line flux to changes in sub-ice-shelf melting
Publication TypeJournal Article
Year of Publication2020
JournalThe Cryosphere
Volume14
Number10
Pages3407-3424
Abstract / Summary

Using a numerical ice flow model, we study changes in ice shelf buttressing and grounding-line flux due to localized ice thickness perturbations, a proxy for localized changes in sub-ice-shelf melting. From our experiments, applied to idealized (MISMIP+) and realistic (Larsen C) ice shelf domains, we identify a correlation between a locally derived buttressing number on the ice shelf, based on the first principal stress, and changes in the integrated grounding-line flux. The origin of this correlation, however, remains elusive from the perspective of a theoretical or physically based understanding. This and the fact that the correlation is generally much poorer when applied to realistic ice shelf domains motivate us to seek an alternative approach for predicting changes in grounding-line flux. We therefore propose an adjoint-based method for calculating the sensitivity of the integrated grounding-line flux to local changes in ice shelf geometry. We show that the adjoint-based sensitivity is identical to that deduced from pointwise, diagnostic model perturbation experiments. Based on its much wider applicability and the significant computational savings, we propose that the adjoint-based method is ideally suited for assessing grounding-line flux sensitivity to changes in sub-ice-shelf melting.

URLhttp://dx.doi.org/10.5194/tc-14-3407-2020
DOI10.5194/tc-14-3407-2020
Journal: The Cryosphere
Year of Publication: 2020
Volume: 14
Number: 10
Pages: 3407-3424
Publication Date: 10/2020

Using a numerical ice flow model, we study changes in ice shelf buttressing and grounding-line flux due to localized ice thickness perturbations, a proxy for localized changes in sub-ice-shelf melting. From our experiments, applied to idealized (MISMIP+) and realistic (Larsen C) ice shelf domains, we identify a correlation between a locally derived buttressing number on the ice shelf, based on the first principal stress, and changes in the integrated grounding-line flux. The origin of this correlation, however, remains elusive from the perspective of a theoretical or physically based understanding. This and the fact that the correlation is generally much poorer when applied to realistic ice shelf domains motivate us to seek an alternative approach for predicting changes in grounding-line flux. We therefore propose an adjoint-based method for calculating the sensitivity of the integrated grounding-line flux to local changes in ice shelf geometry. We show that the adjoint-based sensitivity is identical to that deduced from pointwise, diagnostic model perturbation experiments. Based on its much wider applicability and the significant computational savings, we propose that the adjoint-based method is ideally suited for assessing grounding-line flux sensitivity to changes in sub-ice-shelf melting.

DOI: 10.5194/tc-14-3407-2020
Citation:
Zhang, T, SF Price, MJ Hoffman, M Perego, and X Asay-Davis.  2020.  "Diagnosing the sensitivity of grounding-line flux to changes in sub-ice-shelf melting."  The Cryosphere 14(10): 3407-3424.  https://doi.org/10.5194/tc-14-3407-2020.