Pervasive diffusion of climate signals recorded in ice-vein ionic impurities
A theory of vein impurity transport conceived two decades ago predicts that signals in the bulk concentration of soluble ions in ice migrate under a temperature gradient. If valid, it would mean that some palaeoclimatic signals deep in ice cores (signals from vein impurities as opposed to matrix/gra...
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Copernicus GmbH (for the European Geosciences Union)
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ftleedsuniv:oai:eprints.whiterose.ac.uk:171893 2023-05-15T16:06:17+02:00 Pervasive diffusion of climate signals recorded in ice-vein ionic impurities Ng, F.S.L. 2021-04-13 text https://eprints.whiterose.ac.uk/171893/ https://eprints.whiterose.ac.uk/171893/13/tc-15-1787-2021.pdf en eng Copernicus GmbH (for the European Geosciences Union) https://eprints.whiterose.ac.uk/171893/13/tc-15-1787-2021.pdf Ng, F.S.L. orcid.org/0000-0001-6352-0351 (2021) Pervasive diffusion of climate signals recorded in ice-vein ionic impurities. The Cryosphere Discussions, 15. pp. 1787-1810. ISSN 1994-0416 cc_by_4 CC-BY Article PeerReviewed 2021 ftleedsuniv 2023-01-30T22:37:04Z A theory of vein impurity transport conceived two decades ago predicts that signals in the bulk concentration of soluble ions in ice migrate under a temperature gradient. If valid, it would mean that some palaeoclimatic signals deep in ice cores (signals from vein impurities as opposed to matrix/grain-boundary impurities) suffer displacements that upset their dating and alignment with other proxies. We revisit the vein physical interactions to show that a strong diffusion prevents such signals from surviving into deep ice. It arises because the Gibbs–Thomson effect, which the original theory had neglected, perturbs the impurity concentration of the vein water wherever the bulk impurity concentration carries a signal. Thus no distinct vein signals will reach a depth where their displacement matters; accordingly, the palaeoclimatic concern posed by the original theory no longer stands. Simulations with signal peaks introduced in shallow ice at the GRIP and EPICA Dome C ice-core sites confirm that rapid damping and broadening eradicates their form by two-thirds way down the ice column; artificially reducing the solute diffusivity in water (to mimic partially-connected veins) by 103 times or more is necessary for signals to penetrate into the lowest several hundred metres with minimal loss of amplitude. The deep solute peaks observed in ice cores can only be explained by widespread vein disconnection or a dominance of matrix/grain-boundary impurities at depth (including their recent transfer to veins); in either case, the deep peaks would not have displaced far. Decomposing the vein and matrix impurity contributions will aid robust reconstruction from ion records. Article in Journal/Newspaper EPICA ice core The Cryosphere The Cryosphere Discussions White Rose Research Online (Universities of Leeds, Sheffield & York) |
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White Rose Research Online (Universities of Leeds, Sheffield & York) |
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ftleedsuniv |
language |
English |
description |
A theory of vein impurity transport conceived two decades ago predicts that signals in the bulk concentration of soluble ions in ice migrate under a temperature gradient. If valid, it would mean that some palaeoclimatic signals deep in ice cores (signals from vein impurities as opposed to matrix/grain-boundary impurities) suffer displacements that upset their dating and alignment with other proxies. We revisit the vein physical interactions to show that a strong diffusion prevents such signals from surviving into deep ice. It arises because the Gibbs–Thomson effect, which the original theory had neglected, perturbs the impurity concentration of the vein water wherever the bulk impurity concentration carries a signal. Thus no distinct vein signals will reach a depth where their displacement matters; accordingly, the palaeoclimatic concern posed by the original theory no longer stands. Simulations with signal peaks introduced in shallow ice at the GRIP and EPICA Dome C ice-core sites confirm that rapid damping and broadening eradicates their form by two-thirds way down the ice column; artificially reducing the solute diffusivity in water (to mimic partially-connected veins) by 103 times or more is necessary for signals to penetrate into the lowest several hundred metres with minimal loss of amplitude. The deep solute peaks observed in ice cores can only be explained by widespread vein disconnection or a dominance of matrix/grain-boundary impurities at depth (including their recent transfer to veins); in either case, the deep peaks would not have displaced far. Decomposing the vein and matrix impurity contributions will aid robust reconstruction from ion records. |
format |
Article in Journal/Newspaper |
author |
Ng, F.S.L. |
spellingShingle |
Ng, F.S.L. Pervasive diffusion of climate signals recorded in ice-vein ionic impurities |
author_facet |
Ng, F.S.L. |
author_sort |
Ng, F.S.L. |
title |
Pervasive diffusion of climate signals recorded in ice-vein ionic impurities |
title_short |
Pervasive diffusion of climate signals recorded in ice-vein ionic impurities |
title_full |
Pervasive diffusion of climate signals recorded in ice-vein ionic impurities |
title_fullStr |
Pervasive diffusion of climate signals recorded in ice-vein ionic impurities |
title_full_unstemmed |
Pervasive diffusion of climate signals recorded in ice-vein ionic impurities |
title_sort |
pervasive diffusion of climate signals recorded in ice-vein ionic impurities |
publisher |
Copernicus GmbH (for the European Geosciences Union) |
publishDate |
2021 |
url |
https://eprints.whiterose.ac.uk/171893/ https://eprints.whiterose.ac.uk/171893/13/tc-15-1787-2021.pdf |
genre |
EPICA ice core The Cryosphere The Cryosphere Discussions |
genre_facet |
EPICA ice core The Cryosphere The Cryosphere Discussions |
op_relation |
https://eprints.whiterose.ac.uk/171893/13/tc-15-1787-2021.pdf Ng, F.S.L. orcid.org/0000-0001-6352-0351 (2021) Pervasive diffusion of climate signals recorded in ice-vein ionic impurities. The Cryosphere Discussions, 15. pp. 1787-1810. ISSN 1994-0416 |
op_rights |
cc_by_4 |
op_rightsnorm |
CC-BY |
_version_ |
1766402184025473024 |