Waterside convection and stratification control methane spreading in supersaturated Arctic fjords (Spitsbergen)
Seasonally ice covered in the past, the fjords in West Spitsbergen turn into being perennially ice free in the present. This feedback to Arctic amplification of global warming changes gas fluxes at the atmosphere-ocean interface. Furthermore, in this Polar region, coupled feedbacks likely enhance Ar...
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Online Access: | https://hdl.handle.net/11250/2992702 https://doi.org/10.1016/j.csr.2021.104473 |
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ftunivbergen:oai:bora.uib.no:11250/2992702 2023-05-15T13:05:54+02:00 Waterside convection and stratification control methane spreading in supersaturated Arctic fjords (Spitsbergen) Damm, Ellen Ericson, Ylva Falck, Eva 2021 application/pdf https://hdl.handle.net/11250/2992702 https://doi.org/10.1016/j.csr.2021.104473 eng eng Elsevier urn:issn:0278-4343 https://hdl.handle.net/11250/2992702 https://doi.org/10.1016/j.csr.2021.104473 cristin:1914795 Continental Shelf Research. 2021, 224, 104473. Attribution-NonCommercial-NoDerivatives 4.0 Internasjonal http://creativecommons.org/licenses/by-nc-nd/4.0/deed.no Copyright 2021 The Authors 104473 Continental Shelf Research 224 Journal article Peer reviewed 2021 ftunivbergen https://doi.org/10.1016/j.csr.2021.104473 2023-03-14T17:42:52Z Seasonally ice covered in the past, the fjords in West Spitsbergen turn into being perennially ice free in the present. This feedback to Arctic amplification of global warming changes gas fluxes at the atmosphere-ocean interface. Furthermore, in this Polar region, coupled feedbacks likely enhance Arctic amplification of global warming as numerous gas seepages provide evidence for active gas emissions at the sediment-water interface. We present a time series (2015–2017) of dissolved methane concentrations combined with hydrographic data in Adventfjorden and Tempelfjorden, two sub-fjords of Isfjorden located at the west coast of Spitsbergen. While both sub-fjords remained permanently supersaturated, we detected pronounced temporal and spatial variations in the methane excess level. Our study revealed that seasonal water transformations were key to seasonally changing methane pathways including potential sea-air flux (efflux). We suggest that a cascade of feedback processes, seasonally triggered by waterside convection and stratification, adjusts the amount of methane released and transported within fjord water. When sea ice was missing, strong winter cooling affected the methane supersaturation in contrary directions: first a drop and then a strong increase. In early winter, convective mixing favoured efflux, which reduced the supersaturation. Later in winter, the thermal convection resulted in a continuous overturning of the water column. When the thermal convection reached the bottom, sediment resuspension by turbulence increased, which in turn encouraged enhanced methane release. Subsequently transported along vertical isopycnals, methane from the bottom water reached the water-atmosphere interface. These coupled events created a steady state, simultaneously maintaining supersaturation and efflux. During the warm season, the fjord water became stratified and methane transport occurred mainly laterally in the bottom water. The seasonally changing hydrographic conditions strongly triggered the methane spreading ... Article in Journal/Newspaper Adventfjorden Arctic Global warming Isfjord* Isfjorden Sea ice Tempelfjord* Tempelfjorden Spitsbergen University of Bergen: Bergen Open Research Archive (BORA-UiB) Adventfjorden ENVELOPE(15.515,15.515,78.258,78.258) Arctic Tempelfjorden ENVELOPE(17.076,17.076,78.404,78.404) Continental Shelf Research 224 104473 |
institution |
Open Polar |
collection |
University of Bergen: Bergen Open Research Archive (BORA-UiB) |
op_collection_id |
ftunivbergen |
language |
English |
description |
Seasonally ice covered in the past, the fjords in West Spitsbergen turn into being perennially ice free in the present. This feedback to Arctic amplification of global warming changes gas fluxes at the atmosphere-ocean interface. Furthermore, in this Polar region, coupled feedbacks likely enhance Arctic amplification of global warming as numerous gas seepages provide evidence for active gas emissions at the sediment-water interface. We present a time series (2015–2017) of dissolved methane concentrations combined with hydrographic data in Adventfjorden and Tempelfjorden, two sub-fjords of Isfjorden located at the west coast of Spitsbergen. While both sub-fjords remained permanently supersaturated, we detected pronounced temporal and spatial variations in the methane excess level. Our study revealed that seasonal water transformations were key to seasonally changing methane pathways including potential sea-air flux (efflux). We suggest that a cascade of feedback processes, seasonally triggered by waterside convection and stratification, adjusts the amount of methane released and transported within fjord water. When sea ice was missing, strong winter cooling affected the methane supersaturation in contrary directions: first a drop and then a strong increase. In early winter, convective mixing favoured efflux, which reduced the supersaturation. Later in winter, the thermal convection resulted in a continuous overturning of the water column. When the thermal convection reached the bottom, sediment resuspension by turbulence increased, which in turn encouraged enhanced methane release. Subsequently transported along vertical isopycnals, methane from the bottom water reached the water-atmosphere interface. These coupled events created a steady state, simultaneously maintaining supersaturation and efflux. During the warm season, the fjord water became stratified and methane transport occurred mainly laterally in the bottom water. The seasonally changing hydrographic conditions strongly triggered the methane spreading ... |
format |
Article in Journal/Newspaper |
author |
Damm, Ellen Ericson, Ylva Falck, Eva |
spellingShingle |
Damm, Ellen Ericson, Ylva Falck, Eva Waterside convection and stratification control methane spreading in supersaturated Arctic fjords (Spitsbergen) |
author_facet |
Damm, Ellen Ericson, Ylva Falck, Eva |
author_sort |
Damm, Ellen |
title |
Waterside convection and stratification control methane spreading in supersaturated Arctic fjords (Spitsbergen) |
title_short |
Waterside convection and stratification control methane spreading in supersaturated Arctic fjords (Spitsbergen) |
title_full |
Waterside convection and stratification control methane spreading in supersaturated Arctic fjords (Spitsbergen) |
title_fullStr |
Waterside convection and stratification control methane spreading in supersaturated Arctic fjords (Spitsbergen) |
title_full_unstemmed |
Waterside convection and stratification control methane spreading in supersaturated Arctic fjords (Spitsbergen) |
title_sort |
waterside convection and stratification control methane spreading in supersaturated arctic fjords (spitsbergen) |
publisher |
Elsevier |
publishDate |
2021 |
url |
https://hdl.handle.net/11250/2992702 https://doi.org/10.1016/j.csr.2021.104473 |
long_lat |
ENVELOPE(15.515,15.515,78.258,78.258) ENVELOPE(17.076,17.076,78.404,78.404) |
geographic |
Adventfjorden Arctic Tempelfjorden |
geographic_facet |
Adventfjorden Arctic Tempelfjorden |
genre |
Adventfjorden Arctic Global warming Isfjord* Isfjorden Sea ice Tempelfjord* Tempelfjorden Spitsbergen |
genre_facet |
Adventfjorden Arctic Global warming Isfjord* Isfjorden Sea ice Tempelfjord* Tempelfjorden Spitsbergen |
op_source |
104473 Continental Shelf Research 224 |
op_relation |
urn:issn:0278-4343 https://hdl.handle.net/11250/2992702 https://doi.org/10.1016/j.csr.2021.104473 cristin:1914795 Continental Shelf Research. 2021, 224, 104473. |
op_rights |
Attribution-NonCommercial-NoDerivatives 4.0 Internasjonal http://creativecommons.org/licenses/by-nc-nd/4.0/deed.no Copyright 2021 The Authors |
op_doi |
https://doi.org/10.1016/j.csr.2021.104473 |
container_title |
Continental Shelf Research |
container_volume |
224 |
container_start_page |
104473 |
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1766396953512378368 |