The role of sublimation as a driver of climate signals in the water isotope content of surface snow: laboratory and field experimental results
Ice core water isotope records from Greenland and Antarctica are a valuable proxy for paleoclimate reconstruction, yet the processes influencing the climate signal stored in the isotopic composition of the snow are being challenged and revisited. Apart from precipitation input, post-depositional pro...
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ftcopernicus:oai:publications.copernicus.org:tc93457 2023-05-15T14:02:17+02:00 The role of sublimation as a driver of climate signals in the water isotope content of surface snow: laboratory and field experimental results Hughes, Abigail G. Wahl, Sonja Jones, Tyler R. Zuhr, Alexandra Hörhold, Maria White, James W. C. Steen-Larsen, Hans Christian 2021-10-25 application/pdf https://doi.org/10.5194/tc-15-4949-2021 https://tc.copernicus.org/articles/15/4949/2021/ eng eng doi:10.5194/tc-15-4949-2021 https://tc.copernicus.org/articles/15/4949/2021/ eISSN: 1994-0424 Text 2021 ftcopernicus https://doi.org/10.5194/tc-15-4949-2021 2021-11-01T17:22:29Z Ice core water isotope records from Greenland and Antarctica are a valuable proxy for paleoclimate reconstruction, yet the processes influencing the climate signal stored in the isotopic composition of the snow are being challenged and revisited. Apart from precipitation input, post-depositional processes such as wind-driven redistribution and vapor–snow exchange processes at and below the surface are hypothesized to contribute to the isotope climate signal subsequently stored in the ice. Recent field studies have shown that surface snow isotopes vary between precipitation events and co-vary with vapor isotopes, which demonstrates that vapor–snow exchange is an important driving mechanism. Here we investigate how vapor–snow exchange processes influence the isotopic composition of the snowpack. Controlled laboratory experiments under forced sublimation show an increase in snow isotopic composition of up to 8 ‰ δ 18 O in the uppermost layer due to sublimation, with an attenuated signal down to 3 cm snow depth over the course of 4–6 d . This enrichment is accompanied by a decrease in the second-order parameter d-excess, indicating kinetic fractionation processes. Our observations confirm that sublimation alone can lead to a strong enrichment of stable water isotopes in surface snow and subsequent enrichment in the layers below. To compare laboratory experiments with realistic polar conditions, we completed four 2–3 d field experiments at the East Greenland Ice Core Project site (northeast Greenland) in summer 2019. High-resolution temporal sampling of both natural and isolated snow was conducted under clear-sky conditions and demonstrated that the snow isotopic composition changes on hourly timescales. A change of snow isotope content associated with sublimation is currently not implemented in isotope-enabled climate models and is not taken into account when interpreting ice core isotopic records. However, our results demonstrate that post-depositional processes such as sublimation contribute to the climate signal recorded in the water isotopes in surface snow, in both laboratory and field settings. This suggests that the ice core water isotope signal may effectively integrate across multiple parameters, and the ice core climate record should be interpreted as such, particularly in regions of low accumulation. Text Antarc* Antarctica East Greenland East Greenland Ice-core Project Greenland Greenland ice core Greenland Ice core Project ice core Copernicus Publications: E-Journals Greenland The Cryosphere 15 10 4949 4974 |
institution |
Open Polar |
collection |
Copernicus Publications: E-Journals |
op_collection_id |
ftcopernicus |
language |
English |
description |
Ice core water isotope records from Greenland and Antarctica are a valuable proxy for paleoclimate reconstruction, yet the processes influencing the climate signal stored in the isotopic composition of the snow are being challenged and revisited. Apart from precipitation input, post-depositional processes such as wind-driven redistribution and vapor–snow exchange processes at and below the surface are hypothesized to contribute to the isotope climate signal subsequently stored in the ice. Recent field studies have shown that surface snow isotopes vary between precipitation events and co-vary with vapor isotopes, which demonstrates that vapor–snow exchange is an important driving mechanism. Here we investigate how vapor–snow exchange processes influence the isotopic composition of the snowpack. Controlled laboratory experiments under forced sublimation show an increase in snow isotopic composition of up to 8 ‰ δ 18 O in the uppermost layer due to sublimation, with an attenuated signal down to 3 cm snow depth over the course of 4–6 d . This enrichment is accompanied by a decrease in the second-order parameter d-excess, indicating kinetic fractionation processes. Our observations confirm that sublimation alone can lead to a strong enrichment of stable water isotopes in surface snow and subsequent enrichment in the layers below. To compare laboratory experiments with realistic polar conditions, we completed four 2–3 d field experiments at the East Greenland Ice Core Project site (northeast Greenland) in summer 2019. High-resolution temporal sampling of both natural and isolated snow was conducted under clear-sky conditions and demonstrated that the snow isotopic composition changes on hourly timescales. A change of snow isotope content associated with sublimation is currently not implemented in isotope-enabled climate models and is not taken into account when interpreting ice core isotopic records. However, our results demonstrate that post-depositional processes such as sublimation contribute to the climate signal recorded in the water isotopes in surface snow, in both laboratory and field settings. This suggests that the ice core water isotope signal may effectively integrate across multiple parameters, and the ice core climate record should be interpreted as such, particularly in regions of low accumulation. |
format |
Text |
author |
Hughes, Abigail G. Wahl, Sonja Jones, Tyler R. Zuhr, Alexandra Hörhold, Maria White, James W. C. Steen-Larsen, Hans Christian |
spellingShingle |
Hughes, Abigail G. Wahl, Sonja Jones, Tyler R. Zuhr, Alexandra Hörhold, Maria White, James W. C. Steen-Larsen, Hans Christian The role of sublimation as a driver of climate signals in the water isotope content of surface snow: laboratory and field experimental results |
author_facet |
Hughes, Abigail G. Wahl, Sonja Jones, Tyler R. Zuhr, Alexandra Hörhold, Maria White, James W. C. Steen-Larsen, Hans Christian |
author_sort |
Hughes, Abigail G. |
title |
The role of sublimation as a driver of climate signals in the water isotope content of surface snow: laboratory and field experimental results |
title_short |
The role of sublimation as a driver of climate signals in the water isotope content of surface snow: laboratory and field experimental results |
title_full |
The role of sublimation as a driver of climate signals in the water isotope content of surface snow: laboratory and field experimental results |
title_fullStr |
The role of sublimation as a driver of climate signals in the water isotope content of surface snow: laboratory and field experimental results |
title_full_unstemmed |
The role of sublimation as a driver of climate signals in the water isotope content of surface snow: laboratory and field experimental results |
title_sort |
role of sublimation as a driver of climate signals in the water isotope content of surface snow: laboratory and field experimental results |
publishDate |
2021 |
url |
https://doi.org/10.5194/tc-15-4949-2021 https://tc.copernicus.org/articles/15/4949/2021/ |
geographic |
Greenland |
geographic_facet |
Greenland |
genre |
Antarc* Antarctica East Greenland East Greenland Ice-core Project Greenland Greenland ice core Greenland Ice core Project ice core |
genre_facet |
Antarc* Antarctica East Greenland East Greenland Ice-core Project Greenland Greenland ice core Greenland Ice core Project ice core |
op_source |
eISSN: 1994-0424 |
op_relation |
doi:10.5194/tc-15-4949-2021 https://tc.copernicus.org/articles/15/4949/2021/ |
op_doi |
https://doi.org/10.5194/tc-15-4949-2021 |
container_title |
The Cryosphere |
container_volume |
15 |
container_issue |
10 |
container_start_page |
4949 |
op_container_end_page |
4974 |
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1766272471145644032 |