Quantifying the sensitivity of post-glacial sea level change to laterally varying viscosity

Ophelia Crawford, David Al-Attar, Jeroen Tromp, Jerry X. Mitrovica, Jacqueline Austermann, Harriet C.P. Lau

Research output: Contribution to journalArticlepeer-review

7 Scopus citations

Abstract

We present amethod for calculating the derivatives of measurements of glacial isostatic adjustment (GIA) with respect to the viscosity structure of the Earth and the ice-sheet history. These derivatives, or kernels, quantify the linearized sensitivity of measurements to the underlying model parameters. The adjoint method is used to enable efficient calculation of theoretically exact sensitivity kernels within laterally heterogeneous earth models that can have a range of linear or nonlinear viscoelastic rheologies. We first present a new approach to calculate GIA in the time domain, which, in contrast to the more usual formulation in the Laplace domain, is well suited to continuously varying earth models and to the use of the adjoint method. Benchmarking results show excellent agreement between our formulation and previous methods. We illustrate the potential applications of the kernels calculated in this way through a range of numerical calculations relative to a spherically symmetric background model. The complex spatial patterns of the sensitivities are not intuitive, and this is the first time that such effects are quantified in an efficient and accurate manner.

Original languageEnglish (US)
Pages (from-to)1324-1363
Number of pages40
JournalGeophysical Journal International
Volume214
Issue number2
DOIs
StatePublished - Aug 1 2018

All Science Journal Classification (ASJC) codes

  • Geophysics
  • Geochemistry and Petrology

Keywords

  • Dynamics of lithosphere and mantle
  • Inverse theory
  • Numerical modelling
  • Sea level change
  • Transient deformation

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