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

Crawford, Ophelia and Al-Attar, David and Tromp, Jeroen and Mitrovica, Jerry X and Austermann, Jacqueline and Lau, Harriet C P (2018) Quantifying the sensitivity of post-glacial sea level change to laterally varying viscosity. Geophysical journal international. ISSN Online ISSN 1365-246X Print ISSN 0956-540X DOI https://doi.org/10.1093/gji/ggy184

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We present a method 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 linearised 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 non-linear 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.

Item Type: Article
Uncontrolled Keywords: 2018AREP; IA74
Subjects: 02 - Geodynamics, Geophysics and Tectonics
Divisions: 02 - Geodynamics, Geophysics and Tectonics
08 - Green Open Access
Journal or Publication Title: Geophysical journal international
Identification Number: https://doi.org/10.1093/gji/ggy184
Depositing User: Sarah Humbert
Date Deposited: 21 May 2018 10:48
Last Modified: 21 May 2018 10:48
URI: http://eprints.esc.cam.ac.uk/id/eprint/4282

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